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Hey guys, I'm new to this forum and new to owning my first chevy truck (with a small problem - hopefully!) and I wanted to post this here for some help/advice/guidance. I have done some research on this problem and only found one other post on the internet with this problem so it seems like a rare one! Unfortunately, the post I found died once the OP stopped responding. So here is the story and the problem:. As of yesterday, I am the new owner of my first Chevy truck! It's a: 1989 GMC Sierra 2500 with a TBI 350 It's completely stock and runs great! (while the EST Bypass wire is connected) No check engine light Got it for $500 There is a problem... The truck does not pass CA smog testing Smog Visual: Passed Smog Emissions/sniffer: Passed Smog Functional test: Failed The reason it failed (as printed on the smog failure report) is: Ignition timing is not readable. Also vehicle will not run when single wire tan/black connector is disconnected which is procedure for checking timing. This was my first attempt at resolving the problem: Started the engine and warmed it up Disconnected the tan/black EST bypass connector WHILE the engine was running and the engine went from idling smoothly to a idling rough. Using a timing light: I set the timing to 0 degrees. The engine then began to run smoothly! I reconnected the EST bypass connector. (This was done while the engine was still running - The engine continued to run smoothly.) I shut the engine off I started the engine and it ran perfectly fine. (I thought I had resolved the issue!) Just to double check: I shut the engine off then I disconnected the EST bypass connector again. I tried to start the engine Results: Engine cranks over but does not start After realizing the engine was not going to start: I reconnected the EST bypass connector. The engine took quite a bit of cranking before it started. Once started, it ran fine. Basically I am able to replicate the exact same same problem that the smog shop came across. Based on my research, the correct procedure to check the timing is: Warm up engine Shut off engine Disconnect EST bypass wire Start engine (Cannot get past this step...) Set timing to 0 Shut off engine Reconnect EST bypass wire I'm guessing this is the procedure the smog shop is trying to follow so seems I need to get this to work for them so the smog test passes. I hope this is enough details for everyone. Please let me know if you have any ideas guys. Thanks for the help in advance!