Hi. I am hoping someone can help me.
I have a 1995 GMC with a 350 automatic 4WD. When I start the engine cold it runs great for 20-30 seconds then it seems to flood really bad. Once the engine is warmed up it seems to run fine. I have replaced: the TBI (with a rebuilt from autoline), the map sensor, the egr valve, the coolant sensor, plugs/wires/cap and rotor, the computer, and the O2 sensor. Also I can't find any vacuum leaks. I am completely confused as the truck runs good once its warmed up. Any help would be appreciated. Thanx

 

Which coolant sensor did you change? There is one for the gauge and one for the ECM.

 

I replaced the ECM's coolant sensor. Also to be more specific, the engine doesn't flood in the warmer months just in the winter.

 

you may have got a bad temp sensor or it could just need a tad bit more timing maby a plugged vac line

 

So I bought another coolant sensor and that didn't help either. Now I have 2 extras! I checked all vacuum lines and they are all good. Timing is a 0 degrees per factory specs but I am wondering something. Apparently there was a bit of a bigger cam installed but I can't verify that. If so should I advance the timing a bit? I am new to the whole fuel injection thing as I always have had older trucks but on them I always gave them a bit more advance usually 2 degrees.

 

Some advance wont hurt. Did you check your fuel pressure regulator?

I literally just watched a video of a guy who diagnosed a SBC engine that had a bad regulator. Thing was spraying fuel through the vacuum like there was no tomorrow.

You said you replaced your throttle body, but did you replace the injectors? Check your engine grounds.

 

When I replaced the throttle body I replaced it with a complete rebuilt unit from autoline. It was the whole TBI unit so I am assuming the regulator is good as it is part of the TBI. The part that bugs me is that the injectors are horribly loud. I can hear them from inside the cab of the truck and they get louder as the engine revs. I am not sure if that is related to my problem or not. The crappy part is that autoline won't warranty it anymore as I have sent 2 back already because of other issues. Should I maybe change the injectors?

 

Well try starting the truck and jump out and pull off the TB cowl and air cleaner and watch the injector spray while the while sounds like it's flooding.

I just had the idea to check the injector pulse with a noid light. I'd use this one, personally:
What you do is touch the two pins on the light up to the injector harness and look at the light a steady pulse. If you see a steady pulse on both injector harnesses, then I would replace the injectors. I think it could be possible that the injectors are faulty, or it's possible that the injectors work fine, but they're having an issue from further up stream in the electrical system.

 

So I just ordered a noid light from amazon.com , thanks for the link. I am also wondering the location of all the engine grounds so that I don't miss any. Thanks again for all your help.

 

I started my truck this morning with the air cleaner assembly off and watched my injector spray while the engine was running. I noticed that I have a nice conical spray pattern but I get intermittent heavy bursts of fuel which I think is causing the flooding issue. Is this normal? I shut the truck off and checked the voltage to each injector, both are at 11.50 volts with the key on. Both injectors also have 1.60 ohms resistance. I am not sure if that is what they are supposed to have or not. I also checked the engine grounds and cleaned them but they looked o.k. I am still waiting for a noid light as none of the parts stores around here carry them.