Fuel pump not priming. Now what?

[krs09]

So while I was getting my battery issue corrected, after installing everything looked promising, as I turn the key to the on position I hear NOTHING not a peep. I go to fire her up and it just cranks and cranks, best crank ive heard yet but nothing. I check all the fuses (all good) and I know I have fuel in there. It started ok not 2hrs before that. The PO says he replace the fuel pump with a new old stock unit which I confirmed. Maybe put 50 miles on it... What else is there to check? All fuses look ok - Pump does not prime with key on. In true D form it seems when I fix one thing another takes a shit.:mad: .. What else can I check .. Help..

[Jonathan]

Did the inertia switch get bumped? Plunger popped up?

[DeLorean03]

Have you done any recent work on the fuel pump, or was this just a battery swap ?

[tommyrich]

I had a similar problem recently, drove car, stopped. Wouldn't start. Turned out to be the 2-pin connector right off the fuel pump, just not making good contact. They get loose and corroded over the years. Could be other things too, but it is something to check.
Tom

[Bitsyncmaster]

Use the "RPM relay jumper" to test the pump circuit first.

[krs09]

Have you done any recent work on the fuel pump, or was this just a battery swap ?

Na, Havent touched the pump in weeks. Just got new bolts for the battery to get better connection.

[krs09]

Well I went out at lunch to double check my problems. Still no priming noise with the key turned on. I tried to start it anyway with same results so I put the gray connector (from the CPR) and connected it to the cold start valve connection and it fired up and ran (still no priming noise from the pump). Ive heard not to run it very long like that so im dumping too much fuel, so I run to disconnect it from the CSV and it stalled right out. SO it wont start with the normal connections but will start with CPR plug connected to the CSV but still hear no priming at all. WTF?? Bad CSV?? Ideas?

[Ron]

It's not the CSV or it would not have primed the engine when it started. And you have to think about where the CSV got fuel pressure for it to prime the engine in the first place -- The pump had to of came on! On a lot of cars the pump does not come on when you turn the key on, some do sometimes, and some every time. Try bumping the key to Start and listen closely, you should hear it run then.

I'd try jumping power right to the pump (+ and ground) off ot the battery to eliminate all wiring and see if it will start then (since the ignition wiring is obviously ok).

[krs09]

It's not the CSV or it would not have primed the engine when it started. And you have to think about where the CSV got fuel pressure for it to prime the engine in the first place -- The pump had to of came on! On a lot of cars the pump does not come on when you turn the key on, some do sometimes, and some every time. Try bumping the key to Start and listen closely, you should hear it run then.

I'd try jumping power right to the pump (+ and ground) off ot the battery to eliminate all wiring and see if it will start then (since the ignition wiring is obviously ok).

Thanks Ron I will try that. So far during my owner ship you could hear the pump prime with the key being turned everytime. I would usually have to turn the key on and off a few times to make sure I get soild pressure for start up. Now silence.. I would think the pump is ok because the car ran for a few min and didnt sound awful. Any other ideas?? Does anyone have any comments about the new pump/sender combo from DMCH. My sender is shot too (i think) the gauge is stuck at the 12 o'clock hr mark:bawling:

[Ron]

If that test and the test Dave said works, I'd say he sold another relay ;-)

[krs09]

Use the "RPM relay jumper" to test the pump circuit first.

I really hate to sound like an idiot but what do you mean by "RPM relay jumper"? Jump the RPM relay entirely? How can i do that?

[Rich]

....Jump the RPM relay entirely? How can i do that?

LINK: http://dmctalk.org/showthread.php?1155 (http://dmctalk.org/showthread.php?1155)

[krs09]

LINK: http://dmctalk.org/showthread.php?1155 (http://dmctalk.org/showthread.php?1155)

Dammit. It can just be a relay issue? I just replaced all my relays with the DMCH update kit. My new relay (in there now) is black and blue, the old relay was green and white. Think that makes a difference? Can relays fail that quickly?

[jawn101]

Dammit. It can just be a relay issue? I just replaced all my relays with the DMCH update kit. My new relay (in there now) is black and blue, the old relay was green and white. Think that makes a difference? Can relays fail that quickly?

For what it's worth, the black and blue should be a Bosch part, green and white were generic replacements.

Anything can fail unexpectedly at any time, but you won't know until you try.

Edit: You could also put back your green/white relay as a test. Brand is meaningless if one part is working and one isn't :)

[krs09]

So I played with the car for a bit but to no avail. It was raining so I didnt have a lot of time but I did manage to replace the RPM relay with the orignal that the car came with (green and blue - volvo) but had the same symptoms. I just dont get how this happened allof a sudden. This is one thing i DIDNT have a problem with. I guess Ill try to just put power to the pump to see if anything happens. Now its just a matter of time before I kill the battery by cranking it to death:angry4: AAHHHH!

[DeLorean03]

In a recent thread, another owner had similar sounding issues here:

http://dmctalk.org/showthread.php?7186-RPM-relay-issue

Maybe it wouldn't hurt to see if one of the connectors on the RPM relay is pushed too far back and not making proper connection...?

Did you jumper the RPM relay's female connector and hear the fuel pump running?

[krs09]

:bawling: So, I made my self a sweet little jumper and hooked it up to see what would happen. When I turned the car to the on position I still heard no "buzz" but the car tried to start and then stall out. It would never really run, it would start and run for about 2sec and shut right off. So I reinstalled the new (black and blue) relay and had the same symptoms. I guess I gotta try to see what power I get going to the pump. Other than that what do you guys think? Is it worth getting a new relay if I have tried two seperate relays? Im really reaching for straws now. Calling all experts ! So sorry to be a PITA.

[Bitsyncmaster]

With the jumper on the RPM relay socket you don't need to turn the key to on, the pump should run as soon as you install the jumper.

If your pump is not running with the jumper, a new RPM relay will not help. You need to get a voltmeter and learn how to use it.

[Ron]

I guess I gotta try to see what power I get going to the pump. Other than that what do you guys think?Run power straight off of the battery, as suggested, and be done with all of the guessing about the pump...
FYI- There are small "+" and "-" marks on it, just match them up.

[krs09]

I finally got the car towed back to my house and was able to play with it a little bit. I checked out the wiring going to and from the pump and what a MESS!:eek1: It looks like the PO rigged this up pretty bad, the wire going to the interia switch was cut and taped off. Just the w/p wire going to the pump was connected but very poorly (male spade is ready to come off) so I do not have a stock harness at least at the connector. The PO replaced the fuel pump and just has a black and red wires comin out of the pump (not the stock connector), I know i can get a new fuel pump harness from DMCH #106740 but I really dont know what to do about the wire coming from the front harness.. Its hard to see without dropping the tank but I would hate to have to replace the whole front harness for one connector. Is there any way to find the connector that comes from the harness (w/ both b/p and w/p wires) so I could just splice them together. Anyone have a old harness laying around that they can snip that connector off?? Can you buy them new without the whole harness?? Is it ok to just use the red (positive) wire from the pump and connect it to the white and purple wire coming from the harness without connecting the inertia switch?? Thanks for any help fellahs:wave:

[Mark D]

Since you don't have either end of the fuel pump harness still intact you have a few more options rather than trying to source both ends of the original type connector..

As you mentioned, the short harness from the pump is readily available but it's probably going to be tough to find the mating connector from the front chassis harness. The conector itself is not available separately so unless you can harvest one from a scrap harness and splice it in you probably won't have much luck.

Unless you're really looking to maintain originality the easier and cheaper option would be to just use a different off the shelf connector. Your local auto parts store should have connectors that you can use to make your own short harness from the pump with corresponding connector on the harness.

A simple 2 pin weathertight connector like this would work.
http://www.autozone.com/autozone/accessories/MSD-2-pin-individual-weathertight-connector/_/N-269d?itemIdentifier=139516_0_0_

If you decide to use a non standard set of connectors just be sure they're set up for the correct wire gauge.

[krs09]

[QUOTE=Mark D;106665]Since you don't have either end of the fuel pump harness still intact you have a few more options rather than trying to source both ends of the original type connector..

As you mentioned, the short harness from the pump is readily available but it's probably going to be tough to find the mating connector from the front chassis harness. The conector itself is not available separately so unless you can harvest one from a scrap harness and splice it in you probably won't have much luck.

Unless you're really looking to maintain originality the easier and cheaper option would be to just use a different off the shelf connector. Your local auto parts store should have connectors that you can use to make your own short harness from the pump with corresponding connector on the harness.

A simple 2 pin weathertight connector like this would work.
http://www.autozone.com/autozone/accessories/MSD-2-pin-individual-weathertight-connector/_/N-269d?itemIdentifier=139516_0_0_

If you decide to use a non standard set of connectors just be sure they're set up for the correct wire gauge

Beautiful. That will be perfect. Any idea of the correct gauge. 10-12?

[Mark D]

I'm not sure what gauge the wire is. Does anyone else know? I thought it was listed on the wiring schematic but it does not show wire sizes.

[dmc6960]

I'm not sure what gauge the wire is. Does anyone else know? I thought it was listed on the wiring schematic but it does not show wire sizes.

Probably something I shouldn't say unless I'm 100% sure, to which I am only 90%. I believe it is 14ga, small chance its 12ga but I'm pretty confident on that 14.

[Bitsyncmaster]

Probably something I shouldn't say unless I'm 100% sure, to which I am only 90%. I believe it is 14ga, small chance its 12ga but I'm pretty confident on that 14.

14 AWG will be fine. I think the stock wire is more like 15 or 16 AWG.

[krs09]

Ok. I headed out to the store to pick up some 14g wires and some spade male and female connectors and got to work. After I had both of the wires connected and ready to go I turn the key to on (prime) and got nothin. So I broke out the mulit meter and found I do have 5 volts going to the pump with the key on and a jumper in the RPM relay and the pump seems dead, not a thing. When I take the jumper out and put in the relay I get no reading with the key on ( Normal? ). So now Im thinking the pump is shot but even with no reading from the mulit meter and having the key on I can fell the hoses coming out of the pump pulsating, like fluid is flowing thru but not a sound.. Weird... Im I right in thinking the pump is dead, If im getting 5volts going to the pump with a jumper in place but the pump completely silent? Is it normal to get no reading when using the RPM relay with the key to on? Thanks to all you guys for holding my hand on this:grouphugg:

[SS Spoiler]

I've heard that you can switch the wires to the pump and force the pump backwards to unjamb debris. then hook it up right to run it forward. Do this back and forth and often you can clear the pump to run again. Correct me if i'm wrong because I have not tried it.

[dmc6960]

5 volts is not right! The pump needs 12v to run. Test the voltage with the pump disconnected. If you then get 12v you have bad wiring somewhere. Individually test the 12v and GND leads to the fuel pump with known-good 12v and GND sources.

Get some spare wire and hot-wire 12v and GND directly to the pump. If it still doesn't work, THEN your pump is toast.

[DeLorean03]

5 volts is not right! The pump needs 12v to run. Test the voltage with the pump disconnected. If you then get 12v you have bad wiring somewhere. Individually test the 12v and GND leads to the fuel pump with known-good 12v and GND sources.

Get some spare wire and hot-wire 12v and GND directly to the pump. If it still doesn't work, THEN your pump is toast.


That is 100% correct.

I would strongly recommend either retracing and repairing the wiring to the inertia switch, or you can run dedicated power and ground wires directly from the battery (+) and the frame (-) to the pump. I did option #2 with both my old Hervey's pump with baffle kit and currently with DMC's new fuel pump sender combo - obviously do at your own risk.

[Bitsyncmaster]

You have a bad connection somewhere.

Your pump should run down to 10 volts or so. At 5 volts you would get nothing.

[Ron]

ok. I headed out to the store to pick up some 14g wires and some spade male and female connectors and got to work. After i had both of the wires connected and ready to go i turn the key to on (prime) and got nothin. So i broke out the mulit meter and found i do have 5 volts going to the pump with the key on and a jumper in the rpm relay and the pump seems dead, not a thing. When i take the jumper out and put in the relay i get no reading with the key on ( normal? ). So now im thinking the pump is shot but even with no reading from the mulit meter and having the key on i can fell the hoses coming out of the pump pulsating, like fluid is flowing thru but not a sound.. Weird... Im i right in thinking the pump is dead, if im getting 5volts going to the pump with a jumper in place but the pump completely silent? Is it normal to get no reading when using the rpm relay with the key to on? Thanks to all you guys for holding my hand on this:grouphugg:



i'd try jumping power right to the pump (+ and ground) off ot the battery to eliminate all wiring...
Try it...


run power straight off of the battery, as suggested, and be done with all of the guessing about the pump...
Fyi- there are small "+" and "-" marks on it, just match them up.
....you'll like it!

[DMCMW Dave]

I've heard that you can switch the wires to the pump and force the pump backwards to unjamb debris. then hook it up right to run it forward. Do this back and forth and often you can clear the pump to run again. Correct me if i'm wrong because I have not tried it.

I've done this successfully - if you define success as getting another few weeks of life out of the pump. ..

[Ron]

+1

...the strainer had to of been bad for it to get in there in the first place...tolerances are really tight and who know for how long it's been sucking trash in there.

[SS Spoiler]

Dave, Ron like I said i've not tried it, but it could be a good emergency attempt to get home if your pump locked up. You're right the pickup screen would have to be bad to let in trash.

[Ron]

Been there, done that (was in the dunes in the UP...Michigan) - miles from nowhere.

[Farrar]

it's probably going to be tough to find the mating connector from the front chassis harness.

You mean this one?

http://www.britishwiring.com/2-Way-3mm-Pin-Socket-Connector-p/c822.htm

[jawn101]

You mean this one?

http://www.britishwiring.com/2-Way-3mm-Pin-Socket-Connector-p/c822.htm

OT but that site is a great find Farrar. I've been just browsing it getting ideas for like 30 minutes now. So many connectors that could use a refresh....

[krs09]

Awesome find Farrar, thanks.

I only had a few minutes to play with the car so tested the volts one more time. When I tested the volts last night the batter was pretty dead (only read 4.5-5 volts at the pump). I put the car on a charger/tender over night and when testing it again I came up with 8-9 volts with the key on and a jumper in the relay but still not a sound. I disconnected the wiring to the pump and just tested the lines coming out of the harness and got 11 volts so Im not too sure what to think yet considering the battery was not yet fully charged. I am just so happy there was a improvement in the volts considering I was terrified it was a wiring issue in the front harness. I still had that funny feeling of the hoses pulsating until I cut the power entirely. I know Ron, im going to run direct power from the battery to the pump once I have some more time. I guess ill have to wait until the battery is fully charged to get the best test. I almost want it to be a bad pump rather than a wiring issue for sure. Thanks for all the help as always.. Keep the tips coming! :thumbup: