'94 TBI 5.7 - Stalling with medium-hard throttle, but only after warm restart

[nutjobrob]

Hi Guys,
So the truck's been running great, but this has happened three times in the last two days:
Starts fine cold
runs fine cold in open circuit
runs fine warm in closed circuit

Turn off ignition and wait 5-20 minutes

Restarts fine when warm
idles fine and very light acceleration is fine (like driving through the parking lot at grocery store)
Go to pull out onto highway from parking lot with medium acceleration and she falls on her face and stalls out.
Try to restart normally and she won't. The only way to get her restarted is to hold the throttle all the way open, and then hold it down to keep the revs up for 5-10 seconds (bunch of smoke), then, she's perfectly fine again and accelerates normally with no other problems.

Normally I would never notice this as I drive 40 miles to work without shutting down, and then home again after 8 hours, without stopping anywhere.

New cap, rotor, plugs, wires, temp sensor, and fuel pump relay.

Any help is appreciated.
Rob

 

[MOBS]

Well normally the dead spot like that would be attributed to the TPS....but when you said it wouldn't re-crank without WOT and it chugs smokes after it cranks, that sounds like either something different, or it's something else combined with the bad TPS....like maybe leaky injectors that're releasing their pressure after dying by flooding your intake, thus making WOT the only way to restart, and the chugs would be from the engine being "loaded up", and the smoke from excess unspent fuel. Could you post a vid of it doing that? The whole process involved would help.

 

[nutjobrob]

I think You're right on with the injectors, Mobs. Last night i turned off the truck after a 30 min drive. Tried to start it 30 secs after and it did the same thing. Chug chug, hold the throttle open to keep it going, black smoke. I gotta get out there today and see if they're leaking down after shut off. Maybe I should do a TB rebuild.

 

[kevhill85]

Coolant temperature (ECT) sensor will make a TBI motor run like yours. I hope this help ... It a 15.00 part

http://www.aa1car.com/library/coolant_sensors.htm

 

[MOBS]

Nutjobrob, that's what my yukon had started doing and after firing off with WOT it had a terrible chug-like miss that sounded like an awesome cam and would flood the surrounding air in black smoke. The injectors would both pour a stream of gas after the ignition was turned off for a good 5sec and would steadily drip for a good while afterwards.

The ECT sensor most times will just leave the engine running on choke, which is an all-time rich condition. If it does it after engine has warmed up then yeah, it could be fouling plugs also. If your ECT has never been replaced, might do it just for sake of trying.

 

[nutjobrob]

Yeah, I replaced the ETC a couple months ago because it was running great cold, but stalling out as soon as it got warm. Now it starts fine cold, runs fine warm, but just acts flooded when trying to restart it if it's warm.
I need to get in there and see if the injectors are dripping after warm shutdown. Or any shutdown I guess for that matter.
When injectors leak like that, is it usually the o-rings? Or do the injectors themselves go bad?

 

[nutjobrob]

Oh, BTW, thank you guys for your help on this.

 

[MOBS]

I can't honestly tell you what causes these specific injectors to leak because I've never torn them apart(if it's even possible). The old mechanical types used to have a pintle valve like system with a rubber or brass seat and over time the rubber would deteriorate and cause leakage, or on the brass types the needle tip would wear a groove in it letting pressure escape. So it's probably something similar to those examples that happens with these injectors.

 

[DRAGGIN95]

I have rebuilt a ton of these TBI unit's, I can get a complete rebuild kit at O'reilly auto part's for $42, it includes everything even the little fuel filter's that pop in to the side of the injector's, it really help's any TBI motor run better, and you can do it an hour.

 

[MOBS]

I have rebuilt a ton of these TBI unit's, I can get a complete rebuild kit at O'reilly auto part's for $42, it includes everything even the little fuel filter's that pop in to the side of the injector's, it really help's any TBI motor run better, and you can do it an hour.

Would this help with the "conical fuel spray" you're supposed to have? Like most high-mileage tbi's, one of mine isn't spraying in a cone-shape, but more like a kitchen faucet