CSFI problems?

[T prop]

Has anyone here ever had a problem on their 96 Astro where the engine will start, run and die off in several seconds after start? A friend called me because his is doing just that. I hooked up a fuel pressure gauge and with the key on and the engine not running there's about 60 psi. Once you start it the pressure drops off to about 45 psi at which point it dies. According to a Haynes manual 55 psi is the low limit KOEO, and it can drop up to 10 psi once running. If that's the case it should run at 45 psi, or will it? With the engine and fuel pump off it will hold the 60 psi, so I don't think there's a leak in the system. The van has 130k and one of the first things I did while checking on this was change the fuel filter since it looked like the original.

Any ideas?

[LiftedAWDAstro]

Fuel pump is weak. You need around 50 PSI just to keep it running. At least that is the rule of thumb we have always gone by.

[potskie]

Fuel pump is weak. You need around 50 PSI just to keep it running. At least that is the rule of thumb we have always gone by.

Yuppers. GM says if it's below 55 ( or was it 52?) pump needs to be replaced.

[T prop]

Ok, so the pump does put out enough pressure with the engine not running but with the engine running there must not enough volume then. I ran across this article today online and it mentions that the pump should be able to deliver a quart of fuel in 30 seconds or less, I'll check the volume this weekend to confirm the pump is bad.

Doesn't sound like much fuel, 1 quart in 30 seconds, but I suppose that would be enough fuel to keep the engine running :-k

Thanks for your replies.

[T prop]

More info in case anyone else runs into a problem like this. I checked the volume that the pump is putting out today and found that it will supply a quart + of fuel in under 15 seconds, that's supposed to be good right? So then I connect the line again and check pressure, 62 psi or so with the engine not running, start the engine and it drops to 45 psi till the engine dies. It holds the 45 psi and if you turn the key off and back on to run the pump again it won't kick the psi back up. It will only build up to 62 psi again if I bleed off the pressure to zero and then turn on the pump again. I can hear the pump rpm drop as it gets loaded down pumping against pressure. Maybe I have a voltage drop at the pump? In any case I told my friend to buy a pump and, when we drop the tank, I'll look at the wiring connected to the pump at the same time to see if there are any problems.

Weird, I've changed pumps on other cars before but everyone of them would fail and not run, thereby making it easy to diagnose.

[Cobra]

sounds like that pump is going to kick the bucket soon

[potskie]

Ya that pump is done. that is what mine was doing once in awhile until I replaced it. I would have to pop the dog house and bleed off the pressure via the schrader vavle to get it come back up. So as much as it sucks that pump is done.

[T prop]

Good thing about it is the pump will still move fuel. I plan on disconnecting the line again and using it for the last time to empty the tank, it's just over 3/4 full.

[T prop]

Update: Changed the pump and all is well.