5.7 Vortec, New Fuel Pump, Has 55 PSI to the rail, New Plugs, Has Spark, Engine Cranks, No Start

Asked by Mar 29, 2017 at 12:07 PM about the 1996 Chevrolet C/K 2500 Cheyenne Extended Cab LB HD 4WD

Question type: Maintenance & Repair

From what I remember before my 96 K2500 wouldn't start, the codes that
would show from the OBD II reader were P0301 and P0700. I believe the
engine was running ok with no obvious transmission problems to me. I have
gone through the basic checks of checking the air filter, checking the fuel
pressure (55psi at the rail and holds the pressure for at least 15 min.), I
installed a new fuel pump about 2-4K miles ago, checked the fuel at the fuel
filter for debris and water, I am in the process of changing out the fuel filter (
just because), checking for spark  by using a spark plug test lights (installed
new plugs), I have newer injectors that I changed about 2-4K miles ago (same
time as the pump), checked the pulse at the electrical connection for the
injectors with a noid test light. The engine will not even act like it is igniting and
once in a long time it will back fire. Also, sometimes after cranking it will sound
as if it is continuing to crank and lets out a sound as if it is releasing air once or
twice slowly. My neighbor said he saw the engine rotate in the opposite
direction. I really don't want to pull off the plenum and check the spider
injectors if I don't have to. I was wondering if there is something else besides
clogged injectors that could be stopping the injectors from firing. I did smell
gas but I am pretty sure that the fuel pressure regulator is holding pressure or
else it should be dropping the pressure at the fuel rail. Please let me know if
you have had a problem like this or any knowledge might help. I have had this
truck on non-op for a few years tinkering on it but need to get it running. I am
tired of looking at it in the driveway never moving. It only has 170K miles and
would like to be able to pull our trailer in a month on a camping trip.
Any info would help. Please let me know if you guys have any questions.
I have been looking at forums and haven't seen much on what I'm
experiencing.

5 Answers

73,845

The spider injection should be fine because you say it hold fuel pressure. It should not drop more than 5 lbs. in 3 minutes. 55 lbs is on the low side for fuel pressure, could be due to the fuel filter. You have spark at the spark plugs, and have injector pulse. Plus you say you have new injectors installed few miles ago. Which leaves one thing left to check. Check the engine compression. It should be up around 150 lbs.

1 of 1 people found this helpful.

Thanks for the quick reply. I will test the compression. I did it a while ago on the driver side and it seemed fine but will do it again because I don't remember it. If a cylinder has bad compression what would be my next step?

73,845

Bad cylinder compression is a mechanical issue. See when you get there. Also I was thinking if there was a bad vacuum leak, it wouldn't want to start. I would tighten the intake manifold bolts to 15 to no more than 20 foot lbs. The torque spec. is 12, but Vortec intakes like to leak.

1 of 1 people found this helpful.

Ok what about a leak in the plenum? I thought I might of had a leak there before but it's been a while since the last time I have worked on it since this year.

73,845

The plenum needs to be sealed.

1 of 1 people found this helpful.

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