Silly Question but could I possibly have an ECU?

[HotRodPC]

Looks like a cool system. So actually is EFI, it's just analog in that it doesn't use things like O2 sensor to tune itself or a TPS and things like that, that a computer controlled system would use. You actually tune it yourself with all those adjustments on the ECU aka controller.

Does it have a fuel pump pressure requirement to operate properly? You're certain you replaced it with a proper fuel pump? Have you tried any kind of Carb/Injector cleaner in the fuel tank yet?

 

[BOBNKIM]

We actually bought an aftermarket Fuel Pump but it's suppose to be good to 50psi. My hubbys working 6-12s so I thought I'd join the forum and get some input. He did a little research at work and found info that says a bad coolant temp sensor can make it burn rich, stall, etc Summit has it for $20 so he's gonna order that and throw it in too to see if it helps at all. It is an awesome truck so hopefully we'll get her runnng great again soon. Also having some white smoke coming out exhaust too. If he ever gets a day off, he'll get back to work on it. LOL. Really appreciate all your advise!

 

[HotRodPC]

Hope he sticks with it and doesn't give up and go carb. Especially being a 4x4, the FI is certainly the way to go. I bet when it's running good, it runs real good being a 502 and K20's usually have 3.73 or 4.10 gears. Depending on what kind of wheeling you guys do in it, steep climbs or dives aren't all that great with Carbs that depend on a float bowl and being somewhat relatively level to operate effectively. FI takes care of that problem.

 

[Backfoot100]

If you have white smoke coming out of the exhaust that isn't a good thing. That means you're getting coolant into the cylinders. Usually indicative of a head gasket but could be a cracked head or block too. That could certainly explain why its running so bad and may not even be that EFI system.
Run a compression check or even better a leakdown test.

 

[HotRodPC]

If you have white smoke coming out of the exhaust that isn't a good thing. That means you're getting coolant into the cylinders. Usually indicative of a head gasket but could be a cracked head or block too. That could certainly explain why its running so bad and may not even be that EFI system.
Run a compression check or even better a leakdown test.

Great Point, certainly possible and makes perfect sense. Hopefully not the case, but white smoke ususally isn't good. The best case, is it could be sucking some trans fluid from the vacuum modulator. That too can cause some light white smoke.

 

[BOBNKIM]

Fluids have never been low and no antifreeze in the oil tho. white smoke is very light and it just started doing that after I changed dist and it had been sitting for about a month. also initially started with stalling at stops. Thanks, we will ck vacuum modulator & do leak down test. Soon as i have day off, I'm gonna do some further digging.

 

[Preston]

Welcome to GMSB from Virginia
Good luck with your truck, you can fix it!

 

[75Monza]

Another way out there random white smoke issue I've had before was Brake master leaking into vac booster. Only reason I found it was when I lost brakes, lol.

 

[Termite_Delight]

I have owned 2 of these units. try changing the temp sensor, i used one from a early 90's 4.3 and my problems were solved.