94 stumbles and dies once warm.

[TexasRebel]

1994 GMC C1500. 5.7/4l60e

Got the truck when it wasn't running. Dropped the tank and replaced the sending unit, pump and filter. Truck fired right up, let it idle for about 20 minutes and it drove perfectly fine on the 5ish miles I drove it around the neighborhood. Parked it and went to start the next day, it ran good for a couple minutes then started bucking and trying to stall. Would die unless I gave it a little pedal. Been replacing all of the normal parts that cause these symptoms and still have the issue of it not taking any pedal or changing into any gear without sputtering out once it's warmed up. Some more insight from people that know these TBI engines better than I do would be great.

Replaced: Fuel pump, fuel sending unit, fuel filter, fuel pump relay, coolant temp sensor, coil, plugs, wires, iac, and icm. I also rebuilt throttle body and fuel pressure regulator.

 

[HotWheelsBurban]

What about the cap and rotor? That or distributor is what I'm leaning towards (you done replaced about everything else....). Good luck and let us know! Might help someone else....

 

[1997]

don't see 02 sensor on your list.
My 95 had similar issues, new 02 sensor (ACDELCO), good to go.
Scanner didn't isolate issue, but helped by removing other sensors.

so sounds like you'll need a real scanner to see what's going on.

 

[Drunkcanuk]

What's the chances there was a bunch of crap going through the new fuel filter again and plugging it up. Did you blow the lines out at all?

 

[thinger2]

1994 GMC C1500. 5.7/4l60e

Got the truck when it wasn't running. Dropped the tank and replaced the sending unit, pump and filter. Truck fired right up, let it idle for about 20 minutes and it drove perfectly fine on the 5ish miles I drove it around the neighborhood. Parked it and went to start the next day, it ran good for a couple minutes then started bucking and trying to stall. Would die unless I gave it a little pedal. Been replacing all of the normal parts that cause these symptoms and still have the issue of it not taking any pedal or changing into any gear without sputtering out once it's warmed up. Some more insight from people that know these TBI engines better than I do would be great.

Replaced: Fuel pump, fuel sending unit, fuel filter, fuel pump relay, coolant temp sensor, coil, plugs, wires, iac, and icm. I also rebuilt throttle body and fuel pressure regulator.

Pull the fuel filter and replace it.
Cut the old filter open and look for rust or crud in it.

 

[TexasRebel]

What about the cap and rotor? That or distributor is what I'm leaning towards (you done replaced about everything else....). Good luck and let us know! Might help someone else....

They're also new. Forgot to type it. Haven't replaced the distributor yet.

 

[TexasRebel]

don't see 02 sensor on your list.
My 95 had similar issues, new 02 sensor (ACDELCO), good to go.
Scanner didn't isolate issue, but helped by removing other sensors.

so sounds like you'll need a real scanner to see what's going on.

It's not throwing any codes when I plug into the obd1 port so I'm not sure.

 

[TexasRebel]

What's the chances there was a bunch of crap going through the new fuel filter again and plugging it up. Did you blow the lines out at all?

I pulled the filter out yesterday and it's still clean

 

[1997]

It's not throwing any codes when I plug into the obd1 port so I'm not sure.

Neither did mine.
mine was original, so it lasted awhile.

 

[Sabinoerc]

perhaps look to see if the stalling/bucking starts when it goes into closed loop.