Cylinder 3 Misfire

[rkrepcio]

I have a 96 Tahoe LS with a 350. Put a new motor in it recently. New plugs and wires, new distributor cap, and motor. we replaced the fuel injector assly. checked valve lash. #3 spark plug. checked all plugs. replaced the module and coil with a known good test unit. Did fuel pressure test. read 30 pounds. replaced filter, pump, module, and sending unit. Still misfiring Cylinder 3 only.

 

[SunlitComet]

30 psi ain't going to cut it something is still wrong with your pump system or the pressure regulator on spider. You would need at least about 40psi just to idle with no problems. system right now is like this:

priming 60psi

Priming stops engine not running 53 psi

engine running 52psi Jumps to 60psi when open wide throttle.

engine of 46psi drop to 45 psi in 5 minutes and holds that for at least 40 minutes.

 

[rkrepcio]

After replacing the fuel pump the pressure is back up to 60 psi but the cylinder is still misfiring.

 

[gpracer1]

When is it misfiring?
All the time, during accel, WOT, idle, cruise?
I would check or replace that plug, wire, with known good ones, check the compression on that cylinder, and if all that is good check the valve springs for a broken one.

 

[SunlitComet]

What he said. Would like some more details on when it is happening.

 

[rkrepcio]

She's skipping all around and all the time. We have check the springs and also the plug and wire with good ones. Compression been done and all normal. have really exhausted all mechanical possibilities can think of. Thinking it could be a broken wire in a harness or busted pin in a connector. looking for possibility.

 

[SunlitComet]

Then check you pins and sockets on the injector harness and pcm for breaks and corrosion.