1989 c4 won't start
Thread Starter
Instructor
Joined: Jun 2024
Posts: 104
Likes: 15
From: Sacramento, CA
1989 c4 won't start
Had a misfire under light accel around 2k rpms but wouldn't happen if I went over maybe 1/4 throttle. Sunday it got way worse. Was getting on the freeway and at 1/2 to 3/4 throttle it sounded like a machine gun going off and I had no acceleration. Limped it home using very light throttle. Got into garage. Now it won't start. Just cranks. Checked fuel pump yesterday. It is pumping. Replaced cap. Rotor. Coil and ignition module today. Still won't start. Any ideas guys? Engine was rebuilt from heads up in January. All new sensors. Plugs. Wires. Etc. VATS has already been bypassed. 1989 base with a 6 speed.
Thread Starter
Instructor
Joined: Jun 2024
Posts: 104
Likes: 15
From: Sacramento, CA
Gonna double check and attempt electrocution when I get home. Had to go to a Dr appt.
Also. Is it true these cars don't run a crank or cam sensor? Seriously? How did gm manage to pull that dark magic off?
Also. Is it true these cars don't run a crank or cam sensor? Seriously? How did gm manage to pull that dark magic off?
Last edited by LouKramm86; Aug 14, 2025 at 03:08 AM.
Melting Slicks
Joined: Aug 2011
Posts: 2,844
Likes: 176
Need to find what’s missing , spark or injector pulse or low fuel pressure.
the stock multecs are problematic with age . It just takes one shorted injector to turn off the injector driver. No crank position sensor. The ecm gets a drp from the icm to fire injectors.
the stock multecs are problematic with age . It just takes one shorted injector to turn off the injector driver. No crank position sensor. The ecm gets a drp from the icm to fire injectors.
Thread Starter
Instructor
Joined: Jun 2024
Posts: 104
Likes: 15
From: Sacramento, CA
Gonna test it later today. Picking up a fuel pressure tester from my work and will be checking for spark doing the zap test too. (wire, screwdriver, metal) what should good cranking fuel pressure be? Also my injectors are all new. (6mos old)
Thread Starter
Instructor
Joined: Jun 2024
Posts: 104
Likes: 15
From: Sacramento, CA
Thanks
Big thanks for all the input and info guys! She's alive. There was no spark. Turns out it was the pickup coil on the 35 year old distributor. New reman distributor later it fired right up.
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