Got this 98 Suburban here....wouldn't start and showed fuel pressure of about 42psi. Replaced the fuel pump and filter, and the truck ran great for a few days, and then it happened again. Figured faulty pump, so replaced it again under warranty and cleaned the tank out to be safe.
Again, a few more days later, it quit starting with fuel pressure in the 40s. Thought maybe it was because it was a delphi pump instead of ACDelco, so ordered an ACDelco pump. Installed it, and a few days later the same problem reared its ugly head again.....

At this point i'm lost. Replaced the pump AGAIN. Did some other checking, apparently when the key is turned on the pressure builds up (60psi) and holds for a moment, and then bleeds off. Normal, right? Well, after it bleeds off for a bit(20psi), when the key is turned off....the pressure builds back up again(60psi).
Tried replacing the PCM and its still doing the same thing only now it won't start again.
Any ideas?

 

Possibly a bad fuel pressure regulator.

 

Oh yeah. Replaced that, and checked to see if maybe one of the injectors on the spider were leaking. No leaks, still doing the same thing.

I'm at my wits end on this thing.

 

SO. I've removed the fuel pump relay and supplied 12v direct to the pump from the relay, truck starts and then stalls immediately. Thinking the fuel pump went out again......5th time is the charm?
Unusual thing though....I checked the wire that comes from the PCM and it is being energized for a few seconds when the key is turned off, as well.....When the key is turned on, the PCM gives 12v continuous to the relay control circuit as measured with a DVOM. Turn the key off again, the voltage remains for a few seconds and then cuts off. Wondering if this might be part of why the fuel pumps keep going out....
Thoughts?

 

No. Do you have any security light's with this?

 

Sure don't. Not even a check engine light.

 

Does the pump have a return line back to tank?

 

Rather the fuel rail?

 

There's no rail, it's a Sequential Centralized Fuel Injection system....got a "spider" inside the upper intake manifold.

Yes there is a return line, haven't messed with it yet on this particular pump.

 

Are you saying that the fuel pump has no pressure even with voltage applied to it from the PCM?