Fuel pump voltage

[Bitsyncmaster]

I had a PM from an owner asking about his low fuel pump voltage. So I pulled the cover from my car and measured my voltage.

Measuring the voltage on the pump terminals (- to meter -, + to meter +) I get 11.18 volts with the engine running. Measuring my system voltage from the jump terminal to the engine block I have 14.68 volts.

Now I'm off to track down the voltage drop.

note : The other owner is also seeing 11 volts.

[sean]

Check that inertia switch, they are prone to melting at the connection, but you knew that :)

[Bitsyncmaster]

This time I checked the ground drops.

Battery (-) to pump (-) = 1.14 volts. I tested this again because I took a break.
Battery (-) to inertia switch input = 0.53 volts
Battery (-) to inertia switch output (ground wire) = 0.41 volts

Looks like that connector up front may be dropping some (along with the wire).
The inertia switch is only dropping 0.12 volts, not bad.
The ground wire off the switch should be better than that. Looks like I need to trace that wire. I know Bill says all the grounds at the dash use one common wire. If that is so I have to agree with Bill because that fuel pump should not use a common ground as the dash grounds. That would cause your volt gauge to read 0.41 volts lower.

I'm wondering if the factory crimps on the bare copper wire is causing problems with age. All wire these days is tin plated to stop corrosion.

Also found out the inertia switch connector uses smaller lugs then my emergency jumper with 1/4" lugs. I guess I will make up another emergency jumper with those small lugs.


Don't know what happened to my other posts. They disappeared when I edited this one.

[Bitsyncmaster]

Well the missing posting was because two of us had the post open at the same time. So to summarize. Lets list the current flow for the fuel pump.

1) Battery (+) to fuel pump fuse #7 power
2) Fuse #7 load to RPM relay power (Brown wire)
3) RPM relay output to front "bulk head" connector)
4) Front bulk head to two pin connector near the fuel pump.
5) That two pin connector is wired directly to the fuel pump.
6) The return (pump -) wire also goes to the two pin connector.
7) The return power also uses the front bulk head.
8) The front bulk head to the inertia switch.
9) Inertia switch ground......still need to look how this ground gets "grounded".

I did remove the two pin connector and about 0.50 volts was gained.

I also noted that about 0.50 volts is lost from the fuse load to RPM power in so I suspect a bad connection on that fuse terminal. I still have the OEM fuse block.

[dhaney]

I sent the PM to Dave.

One note is that the car we are working on has an alternator that is only putting out 13.5 volts.

What started all this was the car in question would not run with a stock pump but would run with a Hervey "power pump".

-We found that we were only getting 7 volts at the pump which was not enough for a stock pump.
-First we checked and cleaned all the grounds. This helped a lot especially since the front ground was sitting on top of powder coating.

Finally after we got the volts up over 10 the stock pump would run the car.

After checking, cleaning and ensuring all connections and the inertia switch are as good as they can get. We have narrowed the issue down to the wiring.

Using a stock pump:
-At the RPM relay we are getting full voltage.
-At the inertia switch we are getting 12.5- 12.75 volts
-By-passing the interia switch we get the same 12.5 reading.
-At the pump we are losing another volt so we are reading about 11.5 under load.
-The wire itself not under load reads 12.5.

With the power pump we actually pick up about 1/2 of a volt!

What is very weird is that resistance on the wires show ZERO! Yet when we were running the car and getting almost 12 volts the wire was getting really hot in a very short period.

We are going to use my car as a test vehicle and run larger gauge wire to the pump and wire this into the stock circuit a relay that will let the inertia switch still do its job if needed. If it works well we are considering duplicating this on the car we have been working on.

One note we tested 3 other cars and all three were showing low voltage at the pump, it seems to us that this could explain the reason why so many of our cars chew up fuel pumps.

We have not checked my car yet, but I am going to guess that some how I am not having this problem since the pump I am running has about 30K in mileage and has been in the car for almost 13 years!

Dave mentioned the crimps and solding of the connectors as possibly being part of the problem I can asure you this is NOT a problem on this particular car as not too many years ago all the connectors on the car were cut off and replaced. They were done very well and still look fantastic,although one of them was pushed out a bit, when we found and fixed that it really improved our voltage at the pump problem.

This car also as an improved fuse block.

Dan

[Bitsyncmaster]

Please measure your cars voltages before you modify things so we can track which modifications do the most good. Also note your volt gauge reading on the dash. I have an idea moving the pump ground to the relay may improve your volt reading on the gauge.

Adding a relay to ground the pump will work and should not be hard to install. But I think the problem is more of crimps going bad then voltage drop over the wires. I was reading a voltage drop of 1.14 volts on the pump ground terminal. Your relay will probably bring that drop down to a few tenths of a volt.

Your relay will need a switched 12 volt to one side of the relay coil. I don't see why you can not just attach it to the pump + terminal. Then the other side of the relay coil would got to the normal wiring back to the inertia switch. Then I would find a good frame ground to attach the common terminal of the relay contact to. The NO (open terminal would than attach to the pump (-).

[Bitsyncmaster]

I measured the OEM wire used in the fuel pump circuit and came up with it being 15 AWG. If that is so then at 10 amps each 10 foot of wire would drop 0.3184 volts at room temp. As copper wire heats up it would drop a little more. I would guess you have about 20 foot of wire in the pump circuit (you have to count both the power side and ground side. So not counting the connectors, fuse, RPM relay and inertia switch drops, the best you will see on the fuel pump voltage is about 0.7 volts less then you system voltage.

[David T]

There are several areas of concern for the fuel pump circuit.

The wiring harness connector up by the washer bottle
The #7 fuse in the fuse block
The short harness from the fuel pump to the front wiring harness
The inertia switch and plug. (should be the one with a white paint splotch)
The RPM relay

It is wired differently than most cars with fuel injection. Typically there usually is a power relay controlled by the RPM relay and the inertia switch. And the ground is not usually switched. But with Lucas there are no rules! Between corrosion and heat you can see a large voltage drop. As the voltage drops the amps start to go up increasing the heat causing the voltage to drop and increasing the amps and so on till the amps blow the fuse (or the voltage gets so low the pump can't run)
David Teitelbaum

[Canon20DFan]

So it sounds like to me that we should all run a secondary (replacement) power line to the pump, shunted through the inertia switch. This seems to be a chronic problem in Deloreans, and if Lucas wiring is at fault I would also suspect Jaguars, MGs and Minis to have similar issues.

I guess I'm astounded that a forum member can perform the voltage-drop-per-foot calculation easily and predict the source of the problem...why wouldn't the original engineers do the same? And then use not just the proper guage but use the next "better" guage?

[David T]

It's a matter of economics. Figure the cost to up the gauge of the wires on thousands of cars. There is a big incentive to keep costs down. As the cars get older and things go bad they draw more power then they should and overload the circuits. The wiring and the switches and relays and connectors were borderline to begin with! Just as mechanical things age and go bad so too does the electrical system. It is just that most people do not do any PM on it till things melt.
David Teitelbaum

[Bitsyncmaster]

I'm running a new ground wire from the inertia switch to it's own frame ground. I had measured a 0.41 volt drop on that ground which I think can be done better.

I did not trace the OEM wire since I did not want to pull the center console out at this time. But I suspect that ground wire is common to other grounds and could cause other issues as well.

All our cars will have the same voltage drop over the same wiring so I guess our fuel pumps can run at the lower voltage. But like Canon20Dfan says "maybe this is causing our fuel pumps to die". Now add to that more voltage drop introduced with 30 year old connectors and crimps and problems show up.

[ramblinmike]

Why couldn't you ground the pump to the frame and ground the RPM relay through the inertia switch? That would eliminate one entire set of connections that the fuel pump circuit had to go through while still maintaining the safety feature of the inertia switch. You could also run a direct larger-gague wire from the RPM relay directly to the pump that would be nowhere near 20ft long and eliminate a few terminal connections along the way.

[Bitsyncmaster]

Why couldn't you ground the pump to the frame and ground the RPM relay through the inertia switch? That would eliminate one entire set of connections that the fuel pump circuit had to go through while still maintaining the safety feature of the inertia switch. You could also run a direct larger-gague wire from the RPM relay directly to the pump that would be nowhere near 20ft long and eliminate a few terminal connections along the way.

I wish all the switched circuits did ground switching. Using MOSFETs that really makes the circuit simple. But you would still need to run a heavy gauge wire up to the fuel pump for 12 volts. Then you still need the heavy gauge wire (ground) running back to the RPM relay.

Canon20Fan's idea of a relay up near the pump is a good idea but you need to mount it and use a sealed relay so the sparks from the contacts don't ignite any fuel vapors up there. Of course you could use a solid state relay. That relay would cut about half the voltage drops.

[ramblinmike]

Then you still need the heavy gauge wire (ground) running back to the RPM relay.

Why would you need a heavy ground wire for the RPM relay? They only draw 220ma or so. The pump would ground to the frame. The 'new' RPM relay ground would only need to support the current for the relay itself and the unlock voltage to unlock the doors in the event of an accident.

[Bitsyncmaster]

Why would you need a heavy ground wire for the RPM relay? They only draw 220ma or so. The pump would ground to the frame. The 'new' RPM relay ground would only need to support the current for the relay itself and the unlock voltage to unlock the doors in the event of an accident.

OK....I think I see what your saying. To put the fuel pump (-) right to a frame ground and then use the inertia sensor to feed a signal into the RPM relay to shut off. Thats another good idea. You can even use the door lock wiring to (already near the RPM relay) to signal when the inertia switch has engaged. Let me think of a way to incorporate that.

[Bitsyncmaster]

Well I don't see a way to use that door lock wire because it is driven on and off by the doors being locked or not. That signal also drives the door lock light. So you would need to run the black/purple wire back to the RPM relay for a signal. That signal is normally grounded. It may work to just replace the ground wire on the RPM relay with that signal but it may cause noise issues doing that.

[Canon20DFan]

Let's give the devil his due...it was Dan Haney or Matt Crabtree that told me about using a secondary positive wire to the fuel pump and using a relay to maintain the inertia switch's functionality. I don't know anything about voltage except that you should have what you need at both ends of the wire.

As this thread has revealed, low voltage at the pump appears to be endemic to Deloreans. What is curious is that if it is a wide-spread problem, shouldn't the majority of Deloreans have fuel pump problems?

[Bitsyncmaster]

As this thread has revealed, low voltage at the pump appears to be endemic to Deloreans. What is curious is that if it is a wide-spread problem, shouldn't the majority of Deloreans have fuel pump problems?

It must be our fuel pumps can work at lower voltages. Maybe that's also why some prime and some don't. During the prime you only have battery voltage (12.5 volts on a good battery). They seem to work even with that voltage so when your engine is running you get another volt or two.

I think it's a good idea to check your pump voltage. Doing that has shown me two weak connections in my car. One at the (+) lead on that two pin connector and one at the fuse.

I'm still going to put that new ground on my inertia switch. It's definitely going to reduce voltage noise in the dash circuits along with increasing the pump voltage about 0.3 volts.

Edit:
If you think this voltage drop is bad, check the drop on your OEM cooling fans.

[Bitsyncmaster]

Just as I thought:thankyou:

I made up a new wire of 8 foot of 10 AWG wire crimped and soldered to a ring terminal for a 6 mm screw. I use shrink tubing (two layers) over the terminal not because you need insulation but for strain relief. When you solder stranded wire you make the soldered end solid and therefor it should not be flexed much.

The frame connection is on the shift mount casting. This casting is aluminum and has four bolts holding it to the frame. I had to drill a 1/4" hole to feed the wire up into the center console because of the noise isolator closes up that access.

I cut the black wire about four inches from the inertia connector and spliced my new 10 AWG wire to it (crimp, solder and shrink tubing).

Started her up and measured that voltage drop on that inertia connector pin. It was 0.41 volts and now it is 0.14 volts.

Also included photo of my volt gauge before my change and after.

Note: My 8 foot of wire was cut to 4 foot and 2 inches. So if you do it 5 foot should give you plenty.

[Canon20DFan]

Please explain in more detail...you grounded the inertia switch with a new wire? You didn't run a wire from the inertia switch to the fuel pump?

[Bitsyncmaster]

Please explain in more detail...you grounded the inertia switch with a new wire? You didn't run a wire from the inertia switch to the fuel pump?

Correct. My concern was the original ground was tied to the one common ground that Bill says is used for all the center console. So the fuel pump current (7 to 10 amps) is pushing an offset on all the grounds in the center console.

As you can see, my volt gauge now reads higher (more so than I though it would). So it must have been the dash gauges also shared that ground.

So the voltage gain on the fuel pump would result in 0.27 volts higher.

Using the relay idea rather than my change would probably get you 0.5 volt higher then you had.

[Canon20DFan]

Do you think you'll run a secondary positive wire to the pump?

[Bitsyncmaster]

Do you think you'll run a secondary positive wire to the pump?

I'm not going to run another wire. When I get my new fuse block installed that will give me another 0.5 volts. Since it's been running fine with all these drops and with the new fuse block I should have about 12 volts (about 1 volt higher then before) I think it should be fine.

Now in your case your alternator is running about a volt lower than mine so you may decide to run another wire. That should get you to 12 volts or higher.

I am recommending my ground wire change, especially for those people with low reading dash volt meters.

[jmettee]

I'm a bit lost. I know improving grounds is a good thing...I ran a redundant ground from my center console ground back to the main ground passing through the back wall to the harness area....still need to run one to the ground on the front clip. But is it worth the trouble on this one for the fuel pump? I'm unsure of what the final answer on ground wiring is...& also what the benefit is on a normal, good-running car. Can you provide a simple schematic with your changes highlighted?

[content22207]

I am recommending my ground wire change, especially for those people with low reading dash volt meters.

The whole car isn't grounded worth 2 cents -- just run one large gauge bus from the crumple extension to the engine block (connected directly to the battery of course) that you can tap every ground into and be done with it.

Bill Robertson
#5939

[Bitsyncmaster]

The whole car isn't grounded worth 2 cents -- just run one large gauge bus from the crumple extension to the engine block (connected directly to the battery of course) that you can tap every ground into and be done with it.

Bill Robertson
#5939

Bill's idea works and has the benefit of taping the grounds at any point. But the frame it self is a pretty good ground. Yes it is steel but the "circular mills" (area the current flows) is very high so if a frame ground is near by, it's a good way to get a ground.

[Bitsyncmaster]

I'm a bit lost. I know improving grounds is a good thing...I ran a redundant ground from my center console ground back to the main ground passing through the back wall to the harness area....still need to run one to the ground on the front clip. But is it worth the trouble on this one for the fuel pump? I'm unsure of what the final answer on ground wiring is...& also what the benefit is on a normal, good-running car. Can you provide a simple schematic with your changes highlighted?

There is no schematic change. I just wired the ground connection on the inertia switch to a frame ground (removing the original ground connection). Do you need to do it? No. Should it have been done this way at the factory? Yes. Look at the other high current loads, fans, headlights, blower. They use the frame for the ground circuit.

Edit:
Actually they probably did have the fuel pump grounded at the frame and then decided to implement the inertia switch. Using an existing "off the self" part they implemented the inertia switch in the ground circuit probably so they could also get it to unlock the doors. If it were wired into the power side of the pump you could have just run a short ground wire to the frame at the fuel pump.

[content22207]

... if a frame ground is near by, it's a good way to get a ground.

The frame isn't the problem -- it's the fiberglass body. On a normal car, the entire body is one gigantic ground point. You can drill a hole anywhere and insert a sheet metal screw. DeLorean had to run dedicated ground wires because the body is nonconductive. Where they dropped the ball was ganging too many devices on common wires, and using too small wire gauge (for example, the big bundle of ground wires on the radio bracket are all wires *FROM* devices -- there is only one 16 gauge wire leaving the bracket towards the rear of the car).

Unless you are willing to drill new holes in your underbody, the only frame contact points within the car itself are the body bolts and the seat belt retainer bolts.

Bill Robertson
#5939

[Bitsyncmaster]

The frame isn't the problem -- it's the fiberglass body. On a normal car, the entire body is one gigantic ground point. You can drill a hole anywhere and insert a sheet metal screw. DeLorean had to run dedicated ground wires because the body is nonconductive. Where they dropped the ball was ganging too many devices on common wires, and using too small wire gauge (for example, the big bundle of ground wires on the radio bracket are all wires *FROM* devices -- there is only one 16 gauge wire leaving the bracket towards the rear of the car).

Unless you are willing to drill new holes in your underbody, the only frame contact points within the car itself are the body bolts and the seat belt retainer bolts.

Bill Robertson
#5939

I completely agree.

[content22207]

As would Mike Lund (and a bunch of other Corvette owners).

Bill Robertson
#5939

[Canon20DFan]

Well, I'm going to write a strongly worded letter to the Delorean Motor Company and complain about the electrical system on our cars. I believe a recall is in order.

[Bitsyncmaster]

Well my new fuse block should be here on Friday so I will take the passenger seat out today and hopefully get the new block installed this weekend.

I will measure the voltage drops I get after the block is done and decide if that should complete the fuel pump voltage fixes.

I still like the idea of putting a grounding relay up near the pump but I don't think it would cure anything except preventing high current from flowing through the inertia switch. It will up the pump voltage a little if there is a frame ground close by.

I may also test my stock fuel pump to see how low the voltage has to be to make it stop running.

[sean]

Well my new fuse block should be here on Friday so I will take the passenger seat out today and hopefully get the new block installed this weekend.

Think you could work in a "How-To:"? If you take pictures and make notes I'll post it if you dont have the time.

[Bitsyncmaster]

Think you could work in a "How-To:"? If you take pictures and make notes I'll post it if you dont have the time.

I love these offers. Like most engineers, we hate to write long documents. I will be sure to take photos and notes but may do a writeup anyway.

[sean]

I love these offers. Like most engineers, we hate to write long documents. I will be sure to take photos and notes but may do a writeup anyway.

Sweet! Thanks Dave, the forum will appreciate it.

[Canon20DFan]

All technical people, engineers or software (me) hate documentation...don't even ask them for it, you're wasting your time.

That aside, I'd like to ask for you to document this :tongue2: . There are several independent solutions that I see:

1) create and isolate a new, single ground wire to the inertia switch from the frame
2) create and isolate a new, single ground wire from the inertia switch to the fuel pump
3) create and isolate a new, single positive wire to the fuel pump

Any or all three can be done, likely resulting in increased voltage to the pump. With as many shared grounds as our cars have, and the device (inertia switch) between the ground and the pump, I would start at breaking up and/or cleaning all the ground wires. After that, I'd run a single power wire to the pump directly.

[Bitsyncmaster]

If you do the ground at the pump with the relay then you don't need the ground I did on the inertia switch.

When I test how low the pump voltage can be it will help us decide if we need the other changes.

[jmpdmc]

Sweet! Thanks Dave, the forum will appreciate it.

+1

[jawn101]

Sweet! Thanks Dave, the forum will appreciate it.

I actually am 3/4 way through writing one of these right now! I will post it shortly and put the link here, and I'm sure Dave will have a lot of insight and additions and corrections :)

[jawn101]

I actually am 3/4 way through writing one of these right now! I will post it shortly and put the link here, and I'm sure Dave will have a lot of insight and additions and corrections :)

OK, as promised!

http://dmctalk.org/showthread.php?1070-How-to-Replace-fuse-block

I hope it's clear and detailed enough, it's my first how-to. Hopefully if it sucks Sean will handle edits to it down the line :)

Cheers.

[Bitsyncmaster]

OK, as promised!

http://dmctalk.org/showthread.php?1070-How-to-Replace-fuse-block

I hope it's clear and detailed enough, it's my first how-to. Hopefully if it sucks Sean will handle edits to it down the line :)

Cheers.

Very good document. Thanks. I was thinking of removing one wire at a time and putting the new terminal on and sticking it into the new block. Can that be done? It would save labeling the wires.

I also see some of the pins have double wires. Any problems crimping those? I never like to do that so I may add a new wire on those and butt splice to the twin wires.

[jawn101]

Very good document. Thanks. I was thinking of removing one wire at a time and putting the new terminal on and sticking it into the new block. Can that be done? It would save labeling the wires.

I also see some of the pins have double wires. Any problems crimping those? I never like to do that so I may add a new wire on those and butt splice to the twin wires.

I wanted to do the same thing - but you'll see when you release the block from the clips. There's barely 2" of wire to work with because it routes in every direction. I don't think you'd be able to pull off having 2 blocks in there in parallel.

And no, crimping the double wires wasn't a problem so much as it was just a matter of being extra careful to not let them slip out while you crank down on the crimpers. They still held perfectly fine and fit no problem. I updated the guide to mention this. Thanks :)

[sean]

Hopefully if it sucks Sean will handle edits to it down the line :)

Cheers.

Hey man, great job! Thanks for postin it!

[dhaney]

I was thinking of removing one wire at a time and putting the new terminal on and sticking it into the new block. Can that be done? It would save labeling the wires.

This is how we did this job, three times now, it gets easier every time.

It does save time, especially over the time estimate in the above document! Me and my electrical engineer buddy did it in about 4 hours the first time and less than that the second time.

Dan

[Ron]

This is how we did this job, three times now, it gets easier every time.

It does save time, especially over the time estimate in the above document! Me and my electrical engineer buddy did it in about 4 hours the first time and less than that the second time.

DanSame here.
Do the short ones first...

[Bitsyncmaster]

Took the afternoon off from work and pulled the seat. I ran a die over the seat bolts after I got it out to remove the undercoat and junk off those bolts. By the way you use a 13 mm deep socket for those.

Disconnected the battery and pulled the fuse block up. I do like the idea of pulling up the relay banks to get more room.

I see a problem already. It looks like the brown power wire to the fuel pump fuse is 16 AWG or smaller. WTF....the load wire to the RPM relay (also brown) is larger. I think they used 16 AWG because it's a double crimp to a relay socket. That's one thing I will modify. I bet that contributes to the fuse overheating.

FEDEX has not shown up yet. I hope they do show up with my package today. Got the AC running in the garage.

[jawn101]

Took the afternoon off from work and pulled the seat. I ran a die over the seat bolts after I got it out to remove the undercoat and junk off those bolts. By the way you use a 13 mm deep socket for those.

Disconnected the battery and pulled the fuse block up. I do like the idea of pulling up the relay banks to get more room.

I see a problem already. It looks like the brown power wire to the fuel pump fuse is 16 AWG or smaller. WTF....the load wire to the RPM relay (also brown) is larger. I think they used 16 AWG because it's a double crimp to a relay socket. That's one thing I will modify. I bet that contributes to the fuse overheating.

FEDEX has not shown up yet. I hope they do show up with my package today. Got the AC running in the garage.

Glad someone agreed with *something* I put in that guide :) Good luck, if anyone can do this you can...

[Bitsyncmaster]

Well that brown wire (small) is on the load side of the fuel pump fuse. It goes to the lambda relay and then to the RPM relay. It is a 14 strand 0.0115" dia. which calculates to 17.5 AWG wire. Way to small to power the fuel pump, FV and lambda ECU.

I'm going to install a new wire 14 AWG from the fuse to a butt splice into one 14 AWG wire for the RPM relay and one 16 AWG for the lambda relay.

I know why they did this. Because you can not crimp two large gauge wires into one crimp pin. I saw the same thing on the relay grounds. It used the same gauge wire in a daisy change to ground all the relays.

I don't expect others to do these changes but it explains why some of our circuits have under sized wire.

Well the DMCH fuse block kit looks very good. The block itself looks just like the original. The pins look super good with what looks like spring steel keeping tension on the contacts. Very glad I went the DMCH product.

I haven't really started any installation yet. Just looking over my compartment. I really should pull the steel plate in there and paint it but I don't want this to turn into a month or two project. I also need a new fuse block clip. One of mine has no clip fingers. The old block would not stay down because of that.

I will also look closely at the high beam wiring for wire size since that and the fuel pump fuse are the ones that cause problems.

[dhaney]

Glad someone agreed with *something* I put in that guide :) Good luck, if anyone can do this you can...

I think your document is great, and I really do appreciate the effort.

Dan

[Bitsyncmaster]

Well I couldn't let it go......WHILE I WAS IN THERE, I pulled the metal bracket. One bolt holding it had to ground off the other came out easy (it had anti seize on it).

I also removed the broken bracket that holds the fuse block down. It is pop riveted on that plate. Does anybody sell those? I thought someone was going to make them.

[jawn101]

Well I couldn't let it go......WHILE I WAS IN THERE, I pulled the metal bracket. One bolt holding it had to ground off the other came out easy (it had anti seize on it).

I also removed the broken bracket that holds the fuse block down. It is pop riveted on that plate. Does anybody sell those? I thought someone was going to make them.
So much for a quick project :) happens every time, doesn't it??



Well the DMCH fuse block kit looks very good. The block itself looks just like the original. The pins look super good with what looks like spring steel keeping tension on the contacts. Very glad I went the DMCH product.


I thought so too, I think there's a bit of doomsaying by other vendors about this product in particular.

[Bitsyncmaster]

Four new pins installed into the new block.

Don't waste your time removing the old pins from the old block, just cut the wire off flush to the old fuse block.

I'm using heat shrink tubing about 0.20" ID and 0.70" long. You have to remember to put the tubing on before you crimp the new terminal. With larger tubing than you think you need it will shrink down to a thicker wall then a smaller tubing would.

Wires have been pretty clean but I still sand them with 220 grit silicon carbide sand paper.

Soldering is easy, just put the iron on the opposite side of the terminal and flow the solder onto the crimped side and wires. Be careful not to use to much solder.

Slide your tubing up and shrink it, let it cool before you push it into the new block.

I agree you would have a hard time removing these pins unless you have the proper removal tool. So work slowly and don't rush it.

[Bitsyncmaster]

Both the low and high beam headlight fuses have very large gauge wire on both sides of the fuse. Don't know why that fuse would have a melting problem unless you run higher power lights running near 20 amps.

My car has the brake light fuse near the brake pedal so I'm thinking I may put my WUR regulator fuse in that open location #18.

I'm the doing right row of fuses first and there is plenty of room doing the wires one at a time. See all the room in my photo.

[jawn101]

Both the low and high beam headlight fuses have very large gauge wire on both sides of the fuse. Don't know why that fuse would have a melting problem unless you run higher power lights running near 20 amps.

My car has the brake light fuse near the brake pedal so I'm thinking I may put my WUR regulator fuse in that open location #18.

I'm the doing right row of fuses first and there is plenty of room doing the wires one at a time. See all the room in my photo.

Wow, it's amazing how much more slack you have in your wires than mine. That will definitely make things easier on you!!

[Bitsyncmaster]

Wow, it's amazing how much more slack you have in your wires than mine. That will definitely make things easier on you!!

Also with the metal plate out of the way helps a little.

[Bitsyncmaster]

Slowly getting the wires done. I can't really sit and do the work so it's on my knees. So I do few fuses and take a break.

Now our only 30 amp fused circuit has one of those 17.5 AWG wires on the load side of the fuse :bang: I guess they needed the 30 amp fuse for the window motors (fuse 11) but I would bet the fuse wire terminals into a terminal that could only fit two 17 gauge wires.

[Farrar]

I like the placement of your new ground wire, Dave. Have you thought of routing the many tiny grounds from the radio bracket to the frame there? I imagine it would help.

(For my car, I simply added a 10-gauge ground wire to the radio bracket and routed it to the ground post on the dashboard, but I am thinking of taking that wire and moving its other end from the dashboard to the frame as you did. I have an automatic but the access under the shift plate is the same.)

My car goes through fuel pumps at the rate of about one per year, so I am also investigating a better ground for the pump. Nice one, Dave!

Farrar

[Bitsyncmaster]

I like the placement of your new ground wire, Dave. Have you thought of routing the many tiny grounds from the radio bracket to the frame there? I imagine it would help.

(For my car, I simply added a 10-gauge ground wire to the radio bracket and routed it to the ground post on the dashboard, but I am thinking of taking that wire and moving its other end from the dashboard to the frame as you did. I have an automatic but the access under the shift plate is the same.)

My car goes through fuel pumps at the rate of about one per year, so I am also investigating a better ground for the pump. Nice one, Dave!

Farrar

I wanted to separate the fuel pump current from the dash circuits, hence only one load on that ground. If you wanted a better ground for the dash you could put another ground wire on another bolt to the shifter. I have not done current checking on the dash circuits, maybe someday I will.

Done. Except for installing the WUR fuse in #18.

I did end up not doing any double wire crimps in the fuse block. It turned out the double wires were shorter than the singles anyway. So I butt spiced those in the harness.

Now to move on to getting the metal bracket refinished and make up a new clip to hold the fuse block down.

Here is an idea. Make a new metal plate (relay compartment) out of stainless. I'm not sure my cheap metal brake could do this. Anyone else got a better brake?

Here is the data from my voltage testing of the fuel pump. Note: I have the standard pump from DMCH that is about one year old. My table is the voltage at the RPM relay (white/purple) to the group of black ground wires in the relay compartment.

14.5 volts, 8.1 amps
14.0 volts, 7.9 amps
13.5 volts, 7.7 amps
13.0 volts, 7.6 amps
12.5 volts, 7.4 amps
12.0 volts, 7.2 amps, 76 PSI
11.5 volts, 7.2 amps, 75 PSI
11.0 volts, 7.1 amps, 74 PSI
10.5 volts, 7.0 amps, 74 PSI
10.0 volts, 6.9 amps, 73 PSI
9.5 volts, 6.8 amps, 72 PSI
9.0 volts, 6.7 amps, 72 PSI
8.5 volts, 6.6 amps, 69 PSI

For reference, with that 8.5 volts at the RPM relay, I got 7.1 volts over the fuel pump. I did not dare to try 8.0 volts because the pump was turning very slow at 8.5 and feared it stalling the pump and maybe damaging it.

So from this data I don't see it necessary to add another power wire from the RPM relay to the + side of the pump.

Mine should really be sand blasted and powder coated. I have some rusting spots. But to get that done will take time and probably cost a lot. I could not find if new ones are available. I may just do a quick paint job.

[Bitsyncmaster]

I found a guy 5 miles from my house that can media blast and powder coat. So I'm taking the metal relay bracket to him on Saturday. Have not discussed price or time yet.

[Canon20DFan]

What do the multiple voltage readings mean? Don't you have just one voltage at the pump?

[Bitsyncmaster]

What do the multiple voltage readings mean? Don't you have just one voltage at the pump?

The list is intended for the user to measure his voltage at the fuel pump (terminal to terminal) to see if there will be a problem in the future.

If he reads 7.1 volts with the engine running he has a big problem.

Mine (not tested after my new fuse block) should read about 13.1 volts with engine running. Should not be a problem. My alternator puts out 14.6 volts and I expect the total voltage drop on the wiring and connectors losses to be about 1.5 volts.

If yours reads to low, you can find where the voltage drops are by using a long common test lead on your multimeter connected to the battery ground or "+" and testing the voltage at each junction.

The list was done to determine the minimum voltage required by the fuel pump for correct pressure. It also shows how important it is to have your pump prime the system before starting the car. When your cranking the starter, battery voltage will drop from 10 to 11 volts. Hence the fuel pump will only be getting about 8 volts. Now with a low charged battery you won't have the pump running during cranking but if it primed it would not matter.

Still don't have the metal bracket in but I plugged in all the fuses and relays, started the engine and measured the fuel pump voltage.

Now I get 12.7 volts reading from the terminals of the fuel pump. I still have 14.6 volts at the jump terminal to engine block. So I have improved the voltage 1.5 volts but am still loosing 1.9 volts over the cars wiring and connectors (a little loss at the fuse, RPM relay and inertia switch).

I still suspect I need to rework that front connector by the washer bottle.

The fuse pin and that double pin connector by the fuel pump is where I was loosing about one volt.

Dropped my metal bracket off at 10:00 am and got a call it was done at 5:00 pm. The part looks beautiful and he only charged $25.

I have an idea to use temporarily for the broken clip for the fuse block. Will post if it works out but anyone know where I can get those clips?