about to give up

[Hromeks]

90 Isuzu pickup has run like a dream, then fuel pump quit, replaced 2 to get more pressure, then quit again, Mechanic replaced computer, now it runs for 15 secs and dies. any ideas?

[amigo-2k]

fuel filter?

is fuel getting to the injectors?

[jackass#1]

check fuel filter, ground to pump, and oil pressure switch.

[Hromeks]

Originally Posted by jackass#1

check fuel filter, ground to pump, and oil pressure switch.

Dear friend I really appreciatte your help. The mechanic has tried all of the above several times although the oil pressure switch was a new twist and he did find a bad wire but the engine still starts and quits, have you any other ideas? The mechanic is quite knowledgeable and has spent days on the truck but nothing is working. thanks again, AL

[jackass#1]

does the truck have a fuel pump saftey shut off switch? if so check and make sure its not tripping. this is just a thought(a shoot in the dark).

[jackass#1]

ever figure anything out?

[charlesbill12]

If still you are not able to figure it out then go head and take the car to the local auto motive shop he should be able to help you out with this.

[SleepyHead98]

Got a check engine light? get the codes read. That thing does have a cpu right?

[jamesslcx]

Hook up a gauge and check for proper fuel pressure. It could be an ignition related problem as well. When it stalls pour a little fuel or spray carb cleaner in the intake and see if it will start up. If not check for a spark.

[SleepyHead98]

When you get it started, how does it act if you keep the RPMS up? Does the engine vibrate or otherwise feel like its not working right?

Like previous poster said, put a fuel pressure gauge on it, and watch that gauge to see if/when the pressure drops. It will tell you alot about whats going on.

I say get the codes read, because surely some sensor has to be going off. It is a computer driven engine right? If the cam and crank sensor(if it has one) are throwing codes, you might have to change those out, if they are still bad could be something else.(timing chain)


Car needs air, fuel, and spark. One of those three is not happening/happening at the right time.

Have you had the compression checked?

You say the fuel pump quit, then you put two more in and they quit aswell. Perhaps computer is going bad? something in the wiring? Fuel relay perhaps? I find it interesting that it was working great, then all the sudden stops, and two new pumps dont work? Thats very strange. makes me wonder about the fuel system both electrical and physically *(lines and what not)

[Selador]

Change the alternator.


These vehicles have a circuit in the alternator that takes over after the vehicle has initally started and is running.

When you turn the ignition on, it powers the fuel pump from there, for about 5 seconds.

Then once the engine is actually running, that stops and the alternator circuit takes over.

If the alternator circuit is not working, the vehicle will run for a bit, then die.


I think they did this so that if the vehicle is in an accident, the fuel pump will not continue to run.


The alternator can test to be running perfectly at any of the big box parts stores, but still have a bad circuit for the fuel pump.




You can test for this being the case, by jumpering the fuel pump relay.

As long as the relay is jumpered, the fuel pump will run, so don't leave it jumpered.

If the vehicle starts and keeps running with the relay jumpered, then you need to replace the alternator.