gagliano7

1999 5.3 pcm on a 2004 lm7 in a 1992 chevy truck. The other day I was working on my truck and I turned the key off and on a bunch and I hydro locked the engine with fuel. Lucky I didn't do any damage. I thought I had a leaking injector so pulled the rail off and turned pump on and there were no leaks. I was thinking every time i turned the key on the injectors added some start up fuel. Am I correct?

mattmatt350

Fuel injectors will only squirt fuel when the engine is cranking or running. The computer looks at the crank sensor and cam sensor (if you have one) to spray fuel at correct time in correct cylinder. If your engine locked up from fuel in one cylinder then you have a leaking injector. If multiple cylinders had excessive fuel in them then you have a different problem.

gagliano7

I checked none of my injectors leaked with pressure on them for over an hour. I had the rail out with fuel line connected in a tub and not one drop of fuel came out. Since you said it will only squirt fuel while cranking i must have another problem. Maybe pcm has a problem or a wiring problem.

Old Buzzard

part of the testing. You found none were stuck open.
The other part = What happens when they have the harness hooked up, and power applied?
Did you check them w/ a VOM, to see what the coils are doing?
Check the harness for gnd side shorts?

gagliano7

I didn't check with the multimeter yet. What i understand is they have power all the time and the pcm pulses the ground for them to work. I will also go over my grounds.

gagliano7

So i did a test today with my meter key on and every injector had 12v on power to ground which is correct. Then i checked each injector plug and they all had 5v. I thought they should of zero with key on not running?