1992 C1500 w/5.7 Replaced fuel pump and relay - engine cranks, but no spark and fuel pump won't run while cranking. Normal fuel pressure during prime run - 11lbs - but drops to 0 while cranking. Ignition module and pickup pass tests. Looking for ideas. Thank you. Jeff
Have you checked the "Bump Switch" this is a small inertia switch which turns offf the fuel pump to prevent it running in the event of an accident. They are usually mounted in the boot(trunk/load area) . There should also be one mounted under the front of the vehicle to initiate the Airbags. They usually cut the earh return(at least it does on my Granada, XR3i and Sierra XR4x4) hope this helps.
I installed rebuilt distributor - and it fired right up. Either the module or the pickup was bad - or both. Thank you for your input. Jeff
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Make sure the battery has a full charge. If it cranks good but won't start, have a helper crank it while you visually check for spark at the spark plugs. If spark everywhere, use a gage and check proper fuel pressure, also, check fuel injector pulse. If your missing everything, check cam and crank sensors.
With engine cranking check primary voltage to coil and fuel injectors, brown wire with white tracer. If no voltage leads back to asd relay. I'm not saying that relay is faulty. You can see fuse for that relay, that fuse circuit is hot all the time. The computer grounds the control side of relay if it sees proper cam and crank signals.
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This truck was dead in a garage when I got the call. The owner said they were driving down the road, the motor "popped" or "chugged" a couple of times and died. They towed it home and called me. When I went to check it out, the fuel pump would not run even when I applied 12v to the gray wire that feeds the fuel pump. I am not very familiar with driveability issues and can't afford to guess with their money - or mine. Thank you again. Jeff
I installed rebuilt distributor - and it fired right up. Either the module or the pickup was bad - or both.
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