serioussam1212

So, I've had my 350 TBI for 5 years, and I've never been so stumped. As of right now it's having a strange issue where on a cold start it usually starts immediately, runs like champ....smooth idle, lots of power on the road, but if I park the car and turn it off it won't start again unless I give it lots of gas (but it dies immediately when I let off of the gas), and I should mention the turn-over sounds really rough....almost crunchy. I've replaced the IAC and tried starting the car without the ECM at 0 timing, but neither have affected the problem.

I don't know if this has anything to do with it, but a while back the old starter ate some teeth off of the flywheel, and since then the car has been inconsistently starting and/or running. I'm not sure if that has something to do with it, but I replaced the starter manually turned the engine over to where teeth were lined up with the new starter, and have not had that particular problem since. However, on occasion the car won't turn over at all. I'm pretty sure I can hear the starter engage the flywheel but it just clunks into place and the engine doesn't turn over.

Any ideas or suggestions would be greatly appreciated!

Schurkey

If the flywheel is damaged, the new starter is now damaged too. You will need flywheel and at minimum a new starter drive. Potentially an entire starter motor.

Once the engine cranks properly, we can decide if there's an engine-running problem that also needs to be addressed.

serioussam1212

Ahhhh. Thank you for replying. I was advised by someone else that a few missing teeth on the flywheel wouldn't be any issue unless the motor stopped on that spot wherein I just wouldn't be able to turn the motor over without turning it manually to a point with teeth, but that's not that case?

serioussam1212

Okay, new revelation after further testing. The engine 100% starts when cold but will only turn over when at operating temp.

Schurkey

What is your scan tool telling you about the coolant temperature sensor?

V-8 engines will tend to stop with the crank in four general locations in the rotation. This is due to the throws of the crank--and there are four of 'em.

When the damaged section of the flywheel aligns with the starter motor--or if the starter needs to crank the flywheel until the bad section aligns with the starter drive--the starter is likely to be damaged. I've heard of them getting broken off the block when the "good" teeth finally get rotated under the starter drive with some misalignment of the peaks and valleys of the teeth.

serioussam1212

Okay, so I definitely need to get the flexplate taken care of ASAP then. It's not a flywheel because it's an automatic...just a mistake in terms.

I didn't check the codes during my troubleshooting steps over the weekend because I thought I didn't need to. If I disconnect the ECM entirely (like for when I am setting the timing) the engine still will not start which I believe means that it cannot be a sensor because with no ECM to read the sensors or make adjustments the engine is pretty much entirely mechanical. I might be wrong, but that was my conclusion.

Schurkey

Actually, GM calls it an automatic transmission flywheel. "Flexplate" isn't a GM term.

No, the engine isn't going to run without the ECM. How do you figure the injectors are operated? They're grounded by the ECM as needed to supply fuel based on sensor input. However, disconnecting the wire near the distributor for setting the timing only cancels the computer-generated spark advance. You're not "disconnecting the ECM", you're just forcing the distributor module to provide base timing.

And screw the "codes". You need to be looking at the DATA STREAM on the scan tool.

serioussam1212

Gotcha. Sorry I don't know *official* GM terms. Everywhere I went to buy the part called it a "flexplate".

Also, you didn't specify data stream over codes when you asked if I had hooked it up to a scan tool. I wasn't aware there was a difference. I will now do it when I have time. So I was mistaken about disconnecting the ECM. I thought that is what I was doing, but what you said makes sense. You'll have to forgive me. I'm not a professional mechanic. I'm learning as I go here.