fuel problem

This is a fuel issue. First need to check fuel pump pressure at the Schrader valve on the intake. It should be 56 to 63 lbs. Once the pressure has built up. turn off the key and watch the gauge. It should not drop more than 5 lbs in 3 minutes. If this happens, then it is an indication of leaky fuel injectors, spider lines, and regulator that would have to be replaced as a hole unit.

I'm still betting on a faulty or loose ground connection inside the instrument panel, because there are entirely too many people who have been having the same identical problems with GMC and CHEVY, that have not been able to fix the problem with a brand new complete fuel hanger assembly, and filter, and rebuilt TBI, and new distributor, and all new sensors, and new ECM, and new ICM, and new IAC, etc. Are any of the gauges acting up on you? Is the tranny acting like it's slipping? Is the engine acting like it's trying to start under load?..... I have a newly rebuilt 350 that I dropped in my truck with all of the above replaced new....... The engine will start up with occasional trouble, and won't idle on it's own until warmed up. Then the engine runs like off the show room floor until I drive it...... Then the tranny starts acting up, but it "will" drive "grandma style." ...... After it's warmed up, it will sit and idle for at least an hour the last time I decided to let it idle till it quit on it's own......It didn't quit on it's own......However, I could rev it up to high RMP's and it would miss on a regular cycle, as if it were on a timer to either not fire on one cylinder every second or third revolution, or not receive a signal from the ECM to the injectors on that same cycle...... Check "ALL" ground connections.....Not just the battery to block or battery to chassis....Check grounds to dash frame, to instrument panel..... When the problem first cropped up on my 94 C1500, and I started having the same problem with the rebuilt 350, I also started to notice that....(1) the fuel pump ran for exactly 10 seconds when turned to run, "not started," and continued to run for anywhere from 10 seconds to 20 seconds after the key was "removed" from the switch. (2) The heater fan would come on when "it" wanted to. (3) Temp gauge stayed way too low... (oil pressure gauge stayed way too high immediately, and finally, day before yesterday, the speedo went flat bug-eyed crazy..... I'm going to have to start the probable headache of chasing down a faulty ground or dead short behind my dash tomorrow......Good luck Billy!.... You and I both are going to need all the luck we can possibly muster.

Say there EdMullis, It sounds like you are on the right track on your 94' 5.7L, I had the same with my 95' 5.7L with the gauges. New motor new everything. Ended up being the ground connections, the one to the body especially important. But your and my truck have a OBD1 computer and a TBI set-up. The 1996 year started the Vortec motor with the multi port fuel injection and the OBDII computer witch is all totally different. Fuel pressure on our motors is 9 to 13 lbs, & for the MPFI it is 56 to 63 lbs. The clue in this question is the motor will run when some type of fuel is put directly into the throttle body until it is burnt up.

I'm glad I don't have an OBDII, cause I'm certain that they would be a quintuple headache to try and figure out anything that won' show up in the codes. And some things won't..... I tried to get O'Reilly's or Autozone to put mine on the tester, they can't test anything before 96 cause their connector won't fit, and I guess they're just too cheap to pay for an adapter and computer software to use one on the tester they have. There is a difference when you can spray starter fluid or gas into the TBI and get to run till it runs out of the gas you provided. I did the repair kit on my TBI, it isn't extremely difficult to do. Not getting gas through the TBI can easily be the fuel pump, or relay, or a bad ground to either the fuel pump or relay, or it could be a clogged rail fuel filter, or it could be blocked screens inside the TBI inputs. Or at least that's a variety of the possibilities on my engine. I have not had to dig into a 96 or later yet, and feel intimidated by the multiple fuel injectors. Course I was kind of intimidated by the TBI, and cleaning it, including the repair kit that included the fuel regulator diaphragm, and new screens for the input lines. Till I decided that I had to do it, cause I sure didn't have the money to pay someone else to do it for me, or the extra cash to buy a new TBI unit..... I'm rambling now because I'm procrastinating about the possibility of me going out there and discovering that my problem "is not" a faulty ground connection behind the dash. I'm afraid that I'm wrong, and if I am then????????

Check you main ground points from the battery, to the frame to the motor to the body.