Need help with timing advance will not run with it hooked up can anyone explain why

[jl205]

I have a 93 GMC 1500 5.7 liter with. The motor is a 93 body is a 95. My truck will not run with the timing advanced plug hooked up can someone please help me with this issue. What is the main reason for it to not run with it hooked up.

 

[Dud1f3r]

I had a similar issue on my truck, though VORTEC, not TBI. Make sure your dizzy is stabbed properly. My new dizzy's timing marks were off by a tooth and caused the advance to be so far forward it wouldn't run if the cam position sensor was plugged in. It was a miracle it ran at all, tbh.

 

[Schurkey]

I have a 93 GMC 1500 5.7 liter... ...My truck will not run with the timing advanced plug hooked up can someone please help me with this issue. What is the main reason for it to not run with it hooked up.

Two possibilities:
1. Something's wrong with the mechanical aspect of the timing. A failed damper that's had the timing mark moved; or maybe a mis-matched damper and timing indicator. I suppose a goofy timing light could cause this. You think you're timing the distributor correctly, but it's actually way advanced. Then you plug in the timing connector, it advances the timing even more, and the engine won't run with that much advance. Find TRUE TDC on #1 piston, verify that the timing mark on the damper aligns with "0" on the timing indicator.

2. A failure in the electronic circuitry of the timing advance. Could be a module problem, could be a wire-harness problem, could be in the knock-sensor circuitry, could be an ECM problem. Of these, the ignition module is most likely.

 

[GMCTRUCKS]

Truckers he just wrote down the BEST way to set it thanks for the post.