Fuel pump help. Which one to get.

[pt11334]

So I drove about 30 miles and my fuel pump started making some loud weird noise with half tank left of gas. Not 1st time it does this. The car started to turn off every time I stepped on the gas pedal. I got to the place, parked and open the trunk. I left the car running and the fuel pump was still making this weird noise. I decided to open the gas cap and as I did, gas vapor came out and the car turned off. Try restarting the car and it would turn on and then off . I let the car sit there for 3 hrs. After 3 hrs the car started right away with no problem and I was able to get home. Now, I noticed that the car has done this several times, but with 1/4 of tank left of gas. I think the fuel pump is about to go or maybe is something else inside gas tank. Last time the fuel tank was clean was back in 2005. Don't know if the fuel pump was replaced. Now, if i need a fuel pump, should I just buy the pump for dmc, or hervey. Or should I buy hervey fuel pump kit with the tuna can?

[Michael]

I have always felt that Special T sells parts that will work, DMC sells parts that are correct. In this case where price difference is negligible, go with the DMC.

PS, I had the same symptoms on mine and replacing the pump fixed it. I know many people will disagree on my brand choice but this wouldn't be a DMC board if they did agree. A fuel pump is a fuel pump, and I bet that if I were to look up the number on my DMC pump, I could find it from Bosch but again, the price difference would make it not worth the effort...and I like to support DMCMW.

[DeLorean]

I dislike the fact that the special T auto unit pick up is not at the low point / rear of the tank. Will potentially leave you with a gallon of gas you can't get if you need it.

The new fuel pump set up DMC sells is the same deal... The original set up pickup is at the lowest point & the rear of the tank... which is the best case.

[sdg3205]

buy it off ebay. Martin recommended the model that superseded ours (IIRC) in another thread.

[pt11334]

Im looking at the DMC one. But which model number is the one that Martin recommended from ebay?

[sdg3205]

DCUK Martin
Tweedledumber
Join Date:**May 2011
Location:**DeLorean Cars, UK
Posts: * *307
Type "909 fuel pump" into ebay....

(the 909 pump superceeded the 957 used in the DeLorean, it's operationally identical)
Martin Gutkowski

DeLorean Cars (UK)
www.delorean.co.uk

[Citizen]

So I drove about 30 miles and my fuel pump started making some loud weird noise with half tank left of gas. Not 1st time it does this. The car started to turn off every time I stepped on the gas pedal. I got to the place, parked and open the trunk. I left the car running and the fuel pump was still making this weird noise. I decided to open the gas cap and as I did, gas vapor came out and the car turned off. Try restarting the car and it would turn on and then off . I let the car sit there for 3 hrs. After 3 hrs the car started right away with no problem and I was able to get home. Now, I noticed that the car has done this several times, but with 1/4 of tank left of gas. I think the fuel pump is about to go or maybe is something else inside gas tank. Last time the fuel tank was clean was back in 2005. Don't know if the fuel pump was replaced. Now, if i need a fuel pump, should I just buy the pump for dmc, or hervey. Or should I buy hervey fuel pump kit with the tuna can?

This almost exact thing just happened to me last week. I suspected that the heat from the radiator heated the gas tank, then the gas, and then in turn the pickup hose. When it got hot, it must have kinked at one of the bends (I can't verify this though). Took me 2 1/2 hours to get home, on about a 1 hour (35 mile) trip in heavy traffic.

Anyway, after several road-side failures, delays, and re-starts, I finally got to a gas station and filled the tank. It took 6+ gallons. I waited about 15 minutes for more cooling, started right up and got home without any further stalls.

Is this the fuel pump? Or a bad pickup hose? I know it's not the accumulator, because I just had that replaced.

Thoughts, suggestions?

Oh yeah, one more thing. While driving, I had the fuse/relay cover off. I reached over and felt the RPM relay, and it was so hot I could hardly touch it. After letting the car cool, and finally getting back on the road again, I could touch the relay again, although it was still hotter than what I feel is normal. Any ideas about an extremely hot RPM relay?

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[jmpdmc]

I can tell you that the RPM relay is on as long as the car is on so it can be hot to the touch. I replaced mine with Bitsyncmaster's solid state version and it is always ambient temperature. I recommend it.


Jeff

[jawn101]

I can tell you that the RPM relay is on as long as the car is on so it can be hot to the touch. I replaced mine with Bitsyncmaster's solid state version and it is always ambient temperature. I recommend it.


Jeff

+1, this same suggestion comes up in a huge number of threads. We should just have a sticky that says "buy as much of Dave's stuff as you can afford" ;-)

Seriously though, the internal relay to that original unit runs so hard that it's no wonder it gets hot. Solid state is the way to go with this particular part.

[sdg3205]

If you're having stalling or bucking issues that don't seem to resolve with exhaustive fuel system work, you might have a specific ignition issue - the coil!

I went over every square inch of my fuel system, from taking the tank apart and installing a spring to changing injectors.

When the problem persisted I bought a new Bosch coil at Toby and John's recommendation. They were right. For $36 my car runs like a dream.

Essentially, the coil was toast, and the hotter it got (the longer the car ran) the worse it would get. It would buck and eventually stall. It would refuse to restart for about 10 minutes.

The coil I was running initially was a blue one, so i figured it was a bosch unit. Not the case. Who knows what it was and if it was even a good fit. Probably not.

Just my 2 cents.

[Citizen]

If you're having stalling or bucking issues that don't seem to resolve with exhaustive fuel system work, you might have a specific ignition issue - the coil!

I went over every square inch of my fuel system, from taking the tank apart and installing a spring to changing injectors.

When the problem persisted I bought a new Bosch coil at Toby and John's recommendation. They were right. For $36 my car runs like a dream.

Essentially, the coil was toast, and the hotter it got (the longer the car ran) the worse it would get. It would buck and eventually stall. It would refuse to restart for about 10 minutes.

The coil I was running initially was a blue one, so i figured it was a bosch unit. Not the case. Who knows what it was and if it was even a good fit. Probably not.

Just my 2 cents.

Good information, thank you. Would you say what particular coil you bought (brand, model)?

Also, what do you (or anyone really) think about my theory about the hose getting soft from heat, then kinking inside the tank?

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[sdg3205]

Good information, thank you. Would you say what particular coil you bought (brand)?

Also, what do you (or anyone really) think about my theory about the hose getting soft from heat, then kinking inside the tank?

...

I just bought the standard blue Bosch coil from DMC.

It's not unlikely your hose is kinked or cracked. It certainly has happened before.

Run your tank down normally as far as you can then pull it apart to inspect. there are lots of how-to's on that procedure.

[hillbillydmc]

Hey,
The key to any fuel pump survival is cleaning the fuel tank completely, before install. I run the 957 pump.

[pt11334]

I might change the coil too, but my car has been doing this once my fuel level drops bellow 1/2 tank and been driving for a while. Also that loud pump noise that it makes.

[Jack]

When you have less then half a tank the fuel is no longer "cooling" the over heating pump, it is also not adsorbing the sound waves hence the louder sound.
Last time I talked to John Hervey he mentioned to me that other owners had some problems with fuel pumps acting up do to over heating, caused by low voltage to the pump.
Hervey explained to me that the lower the voltage to the pump the hotter it will get and the shorter its life will be.
So he has been asking owners to test the voltage at the pump.
When I checked mine it was 11.25 volts.
I did a quick check at the top connection cleaned it and added some dielectric grease.
The voltage increased to 11.65 volts.
Next I will be checking the voltage at the fuse to try and track down where the drop/drops occur.
Currently my pump has never over heated and I've driven from Pittsburgh PA to Augusta GA.
I'm simply doing this to prolong my fuel pumps life.

[sdg3205]

When you have less then half a tank the fuel is no longer "cooling" the over heating pump, it is also not adsorbing the sound waves hence the louder sound.
Last time I talked to John Hervey he mentioned to me that other owners had some problems with fuel pumps acting up do to over heating, caused by low voltage to the pump.
Hervey explained to me that the lower the voltage to the pump the hotter it will get and the shorter its life will be.
So he has been asking owners to test the voltage at the pump.
When I checked mine it was 11.25 volts.
I did a quick check at the top connection cleaned it and added some dielectric grease.
The voltage increased to 11.65 volts.
Next I will be checking the voltage at the fuse to try and track down where the drop/drops occur.
Currently my pump has never over heated and I've driven from Pittsburgh PA to Augusta GA.
I'm simply doing this to prolong my fuel pumps life.

Careful, dielectric grease is NOT conductive. It will inhibit and increase resistance. Your increase in voltage was probably due just to cleaning. I bet if you get rid of the dielectric grease between the connections you'd see even higher voltage!

[Jack]

Careful, dielectric grease is NOT conductive. It will inhibit and increase resistance. Your increase in voltage was probably due just to cleaning. I bet if you get rid of the dielectric grease between the connections you'd see even higher voltage!

Yes, but wouldn't there have to be a (gap between the connectors)/(a lose connection) for the grease to be trapped in.
The grease for the most part is simply pushed/scrapped out of the way by a "tight" connection.
The remaining grease surrounds the connection adding protection against corrosion.
Well at least that's how I understand it to work.
From most sites I've read the consensus seems to be that any voltage loss caused by the grease would be negligible compared to the added protection.
Then again it took 30 years for the connection to degrade to that state in the first place, so I can see were people on the "clean only" side are coming from.
This may have started to get off topic... My bad...

[Bitsyncmaster]

When you have less then half a tank the fuel is no longer "cooling" the over heating pump, it is also not adsorbing the sound waves hence the louder sound.
Last time I talked to John Hervey he mentioned to me that other owners had some problems with fuel pumps acting up do to over heating, caused by low voltage to the pump.
Hervey explained to me that the lower the voltage to the pump the hotter it will get and the shorter its life will be.
So he has been asking owners to test the voltage at the pump.
When I checked mine it was 11.25 volts.
I did a quick check at the top connection cleaned it and added some dielectric grease.
The voltage increased to 11.65 volts.
Next I will be checking the voltage at the fuse to try and track down where the drop/drops occur.
Currently my pump has never over heated and I've driven from Pittsburgh PA to Augusta GA.
I'm simply doing this to prolong my fuel pumps life.

Good work Jack. You probably moved that two pin connector up near the fuel pump to get the voltage gain. I suggest you get rid of that connector to reduce voltage drop. The fuse is another place I had voltage drop on mine. But expect the harness wires to drop some voltage.

[jawn101]

Good work Jack. You probably moved that two pin connector up near the fuel pump to get the voltage gain. I suggest you get rid of that connector to reduce voltage drop. The fuse is another place I had voltage drop on mine. But expect the harness wires to drop some voltage.

Where are you guys checking the pump voltage? Across the two connectors at the top, or are you backprobing the connector to the harness? I'd be a little worried checking right at the pump that I might short something and cause a spark.

[Bitsyncmaster]

Where are you guys checking the pump voltage? Across the two connectors at the top, or are you backprobing the connector to the harness? I'd be a little worried checking right at the pump that I might short something and cause a spark.

You want to check right across the two pump terminals with the engine running. Then if you are looking for where voltage drops occur, I use the battery ground lug as the reference and follow all the points in the pump power and ground circuit. You would be surprised how much voltage gets dropped over each contact point and the wire itself.

The voltage at my pump can drop to a pretty low voltage (think it was 8 volts) before it stops working. But I feel better knowing the voltage is above 12 volts right over the pump.

[Citizen]

I was finally able to recreate my engine dying problem. I started my car in my garage, let it warm up and eventually it just quit (like it did on the road). So I restarted the car, and after a few minutes it died again (just like it did on the road). And again.

Okay, so based on what I've read here, I need to:

1. Replace my coil
2a. Load a screen-door spring into my fuel pump pickup hose to keep it from collapsing when it gets hot
or
2b. Upgrade to the new style fuel pump once it becomes available from DMCH, which should also resolve the possible colapsing pickup hose problem.

These two things should solve my car dying problem.....RIGHT?

Thomas

[Bitsyncmaster]

I was finally able to recreate my engine dying problem. I started my car in my garage, let it warm up and eventually it just quit (like it did on the road). So I restarted the car, and after a few minutes it died again (just like it did on the road). And again.

Okay, so based on what I've read here, I need to:

1. Replace my coil
2a. Load a screen-door spring into my fuel pump pickup hose to keep it from collapsing when it gets hot
or
2b. Upgrade to the new style fuel pump once it becomes available from DMCH, which should also resolve the possible colapsing pickup hose problem.

These two things should solve my car dying problem.....RIGHT?

Thomas

Your lucky you can get the failure to repeat. Try the same test with the RPM relay jumpered. You would need a jumper from the brown wire to the white/purple and a jumper from the brown wire to the double yellow/red wires. This will eliminate one common failure fault (the RPM relay).

It sounds to repeatable to be the fuel pump itself. Could be the igition coil or ECU.

[jawn101]

Your lucky you can get the failure to repeat. Try the same test with the RPM relay jumpered. You would need a jumper from the brown wire to the white/purple and a jumper from the brown wire to the double yellow/red wires. This will eliminate one common failure fault (the RPM relay).

It sounds to repeatable to be the fuel pump itself. Could be the igition coil or ECU.

Agreed, it seems like the the pickup hose collapses when the fuel is hot, which usually means the ambient temperature is high or the car has been running hard and the fans are blowing a lot of hot air back onto the tank. I wouldn't imagine it would do it after just idling up to temp in a garage, especially in a temperate climate like Houston in March.

[Citizen]

Agreed, it seems like the the pickup hose collapses when the fuel is hot, which usually means the ambient temperature is high or the car has been running hard and the fans are blowing a lot of hot air back onto the tank. I wouldn't imagine it would do it after just idling up to temp in a garage, especially in a temperate climate like Houston in March.

When I was able to repeat the failures, the car warmed up to normal operating temp. The fans came on and went off as I think is normal, until eventually the engine would quit.

I know it's only March, but with the car not moving and in my garage, there was not much air cooling. That's why I suspect there was a lot of hot air over the fuel tank. The engine never over heated of course (which is good), so the cooling system was doing its job throwing the hot air elsewhere.

I had previously replace the RPM relay. Looks like I'll try replacing the coil.

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[David T]

How much fuel is there in the tank? If it is 1/2 full or less then, Yes, the pick-up hose is a prime suspect. If it is soft and mushy replace it. If it feels firm you can try putting the spring in it. Make sure it is not twisted and kinking when you install the fuel pump.
David Teitelbaum

[sdg3205]

It's totally up to you but maybe hold off on the coil until you can rule out fuel. It's not gonna break the bank at $36 but just eliminate fuel first. Do you still have the blue Bosch coil?

[Citizen]

How much fuel is there in the tank? If it is 1/2 full or less then, Yes, the pick-up hose is a prime suspect. If it is soft and mushy replace it. If it feels firm you can try putting the spring in it. Make sure it is not twisted and kinking when you install the fuel pump.
David Teitelbaum

The tank was full, except for maybe 1/2 gallon.


It's totally up to you but maybe hold off on the coil until you can rule out fuel. It's not gonna break the bank at $36 but just eliminate fuel first. Do you still have the blue Bosch coil?

Yes, still have the blue Bosch coil. Looks pretty raggedy...could it be the original?

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