89 350

My neighbor having big trouble with stalling after running for a few minutes.
He says pressure OK. If he primes, It will keep running. He replaced ECM.
I hope we can help him. Thanks

Define 'ok'.....what kind of psi is he getting? Spec is 9 - 13 psi but I have had trucks that would run like crap on anything less than 11 psi.....

What causes the stall? Loss of fuel or spark? Fuel filter changed recently? Fuel pump turn on when key is turned to 'on'? Gas ok? No water in the gas?......

I start the truck, it runs for 3-5 seconds. It appears to shut off the fuel.
Pulled codes only code was a 45 (too rich)
We started it and squirted fuel into the TBI it ran for about 10 seconds then I think it was too much fuel and stalled.
Things we tried...
Fuel pump relay, fuse is good and does run the pump when key is turned on
Oil Pressure fuel pump cut out (found out from another truck we have that they will run with that disconnected)
O2 sensor... thought it was reading too rich and was shutting off fuel ( also found from other truck that they will run without it hooked up)
TBI tried that figured that eliminated TPS, Idle bypass, injectors, reg all at once.. didn't help.
Distributor (thought it wasn't giving a ref signal and computer didn't know engine was running, no help)
Computer from identical truck... didn't help...
tried 12v straight to the pump it still shut down at the injectors. Like it was being told not to inject fuel.
Going to hook up fuel pressure gauge today to see if it is loosing pressure while it is dies
Tank sender unit, fuel pump, fuel lines filter have all been replaced about 18 months ago (8000 miles)

Only thing left in the fuel circuit that we didn't change is the coolant sensor...

CTS is possible.....

When you changed the distributor did that include swapping in a new ICM??

Definately check the fuel psi and then post back.....

Go figure... went out this morning, put the gauge on inline before the fuel filter. Got in hit key and it sits there and purrs... sounds and runs nice.
Wasn't too happy with the pressure... it fluctuates between 10-13 psi while running but before it starts it dead heads at about 10. Why would it be fluctuating at an idle by that much ? Pump ?

What happens to the pressure when you pinch the rubber section of the return line?

Last night we pinched the return line, it had 17 psi. ... Went out this morning fired it up and it ran like shit... fuel pressure was fluctuating again... could hear the pump cycling, went to pull the tank to put in new pump, found ground wire to frame for pump a little corroded (sp). Ran a wire from ground up front into wiring harness to the tank soldered it to the ground wire from the tank. Runs great, has almost 15 psi when running. Intermitant ground was the problem the whole time... boy does that hurt... one thing we normally check on everything, but forgot that the assholes who designed this system ... run a ground wire all the way to the tank for the sender unit, but don't feed it to the pump... they rely on a shitty ground connection to the frame...
I hope this helps anyone else that chases their tail, I know I said in the begining it'll be something simple that we keep overlooking... :screwy:

Glad you got it figured out....

Thought we did fix it... ran good for two days and then same thing. This time we pulled the fuel pump out and found... the wires on the sender unit (which is one year old) had a brownish burnt look on the wires at the plug inside the tank. Found out that they had a problem with that and the new fuel pump came with a new wiring harness. I found out from a friend that his new sender unit from GM purchased about a month after mine came with a note to replace the "new" wires one the unit... that is a good one... Now if we can go for more than 2 days we'll be doing good. What got me mad is the original pump and sender unit lasted for 15 years and 188,000 miles the one we put in lasted for 1 year 8,000 miles...
We'll keep you posted and let you know if this was the permanant fix...

Thought we did fix it... ran good for two days and then same thing. This time we pulled the fuel pump out and found... the wires on the sender unit (which is one year old) had a brownish burnt look on the wires at the plug inside the tank. Found out that they had a problem with that and the new fuel pump came with a new wiring harness. I found out from a friend that his new sender unit from GM purchased about a month after mine came with a note to replace the "new" wires one the unit... that is a good one... Now if we can go for more than 2 days we'll be doing good. What got me mad is the original pump and sender unit lasted for 15 years and 188,000 miles the one we put in lasted for 1 year 8,000 miles...
We'll keep you posted and let you know if this was the permanant fix...

Sounds familiar.....I had an 88 that I replaced the fuel pump 3 times within a month before I got one that actually worked.....what a pita......glad I don't have to take my stuff to a shop!