fuel pump or regulator problem, I dont know

[Kevin B]

Hi all
well today I went down the road and all was fine, stopped at shop did my stuff and went to come home, discovery started but was rough like it was starving for fuel then stopped when I tried to start it again it was firing but not going then it would stsrt rough for about 5 seconds then stop, tried starting again it just kept turning over and nothing, ok so I tried key on key off a few times to prime the pump and it did the same was firing but just would not go, there was too much noise around the hear if the pump was actually working or not, so I bit the bullet and called nrma, he got there didnt even look just called a tow truck WTF these guys are just jump starters im convinced of that, anyway got it towed home and put in driveway, after the tow truck left I tried it again and it started no problem like there was nothing wrong, im now at a loss as to what it is, could it be fuel pump with an intermittant fault does that happen? Or could it be the regulator with an intermittent fault, does this happen or when they fail they fail... any ideas folks?

1993 3.5l pre update model

[bee utey]

Fuel pumps as they age develop intermittent stopping. Bumping the bottom of the fuel tank hard ( boot, lump hammer, piece of 4 x 2 etc) often starts the pump up again.

Then there's a number of connectors that can overheat and fail, including the one on top of the pump housing and the one above the rear muffler. Look for blackened plastic around the pins and replace as required.

[Kevin B]

Fuel pumps as they age develop intermittent stopping. Bumping the bottom of the fuel tank hard ( boot, lump hammer, piece of 4 x 2 etc) often starts the pump up again.

Then there's a number of connectors that can overheat and fail, including the one on top of the pump housing and the one above the rear muffler. Look for blackened plastic around the pins and replace as required.


Thanks Bee utey, so merely the act of loading it on the truck and a bouncy ride home could have shocked the pump a bit, ok ill check the connectors if I can find them, thanks again, do regulators intermittently fail also

[Kevin B]

Ok so I took it for a drive to get it up to temperature around the suburb no problem at all got back in driveway turned her off tried to start again after 2-3 mins same problem this time I cant hear the pump when I turn ignition on but I could before I went for a drive, so it appears the pump fails when its up ti temperature, ill try again after a few hours when shes cold agian that should confirm it, the pump in these is accessed from the cargo area floor if Im correct ?

[Kevin B]

Okwent back out turned ingnition on temp guage showed 30deg heard fuel pump started no problem let it run till it was up to 85deg or so turned it off then tried agian same thing no start and no fuel pump sound, so it looks like a new pump is needed, ill pull the back out later on and check the conections first see if thats the problem but I suspect a pump gone south

[Gary S11]

Hi I think the pump gets it signal from the coil, it wouldn't be a connection going bad when the coil is hot...and I think it's the white wire...bee-utey would know for sure...Gary

[Kevin B]

Hi I think the pump gets it signal from the coil, it wouldn't be a connection going bad when the coil is hot...and I think it's the white wire...bee-utey would know for sure...Gary

It's kind of weird though, once I start then engine from cold it turns of and on no worries it runs no problem even after I get it up to temperature it still runs and keeps running only when its turned off does it not start again until it cools down again

[bee utey]

It's kind of weird though, once I start then engine from cold it turns of and on no worries it runs no problem even after I get it up to temperature it still runs and keeps running only when its turned off does it not start again until it cools down again
If you saw how worn the commutator on a fuel pump can get, you'd understand why they stop working like they do. While they run they create enough vibration for the brushes to contact the rotor. When they stop there could be a dead spot and only cooling down makes the brushes contact the rotor.

Also regulators generally die and stay dead.

As for the ignition coil connection, that is for the ECU, which receives the rotation signal, and in turn switches on the pump relay and fires the injectors.

Worn pump dismembered. (http://www.aulro.com/afvb/technical-chatter/96033-exploded-efi-fuel-pump.html)

[Kevin B]

Thanks again Bee Utey, a new pump it is then... n8w to find one quickly

[Kevin B]

Ok got a new pump andput it in all goo, back on the road, pulled the old pump apart very easily, the pump only is a delphi 6443255 common vn fuel pump ill fix this one and keep itas a spare