doityoureself

I just replaced head gaskets on my 1996 GMC Sierra 4.3, I fired it up without any water in it so I know it is leaking gas and not water. Fuel is filling up the back cylinders #5 & #6, the first time I tried to start it the timing was slightly off and it cranked for a couple of turns and then CLUNK, fuel filled the cylinder and would not let the engine turn over. After pulling plugs, turning the engine over by socket to drain the fuel out(probably got about a cup of fuel out of each back cylinder) and resetting the timing it will fire up fine, probably running on 4 cylinders, gas immediatly starts running out of muffler/tailpipe. I took the upper intake off, cleaned out the injectors and fuel regulator, put back together and the same thing happened again, flooding out bad. So the third time I took the upper intake off again took the regulator apart and cleaned it again but I left the upper intake off where I could see what the regulator, injectors and body were doing. Hooked up all the wiring connections and bumped the engine. nothing leaked. Put the upper intake back on and everything back together again and sure enough it leaked again. I am hoping that someone can help me, I have searched all over the net and cannot find any similar problems solved for this engine. I am going to get a regulator first. I am hoping that it may leak when under the upper intake manifold and not leak when not under the upper intake manifold due to vacuum being introduced when the regulator is under the intake. Any other ideas or disagreements?

shamrock246

it is probably leaking at the regulator the vacuum might matter,you could try it again maybe bypassing the fuel pump relay so it will run continuously

Sean
97 4x4 burb