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TBI 350 Halp!

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Old 02-19-2017, 08:25 PM
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TBI 350 Halp!

OK, first off, I've been lurking for a week or so now just soaking up what I can, and I have to say, I'm excited to start my journey here. I'm new to American muscle, so everything is new to me.

OK, on to the business: last week, I acquired a 90 Firebird 350 TBI (told 350, haven't verified numbers). When I first got it, it would only start with starter fluid, and was running very rough, but I got it to my shop. As it sat idling, it blew the heater valve and voided the coolant everywhere. Replaced the valve that night, hooked up vacuum lines that were everywhere, and replaced the pcv valve. It still wouldn't start without starting fluid, ran OK after start on its own. Drove it a few times the next day. Day 3, I had it idling for a couple minutes, and it died. Now will not start, even with fluid, which I hate using anyway, since then. Last night, I replaced the fuel filter, and can hear the pump priming, I tried to test for spark, but due to what I assume is user error, I couldnt get it to spark. Changed oil/filter. Tried to test injector pulse with noid light, but get nothing. Had fuel up to the throttle body. Tonight, as part of tune up, I removed the throttle body and rebuilt it...gaskets were gross so figured it needed done whether or not it helps it not starting. On that tune up list is is plugs, wires, dizzy cap/rotor. Might also note it has new ignition coil. Other than that, everything is trial and error. I'll be tracing wires and checking for good ground tomorrow, but like I said, first American muscle car, so looking for some direction and tips.

Thanks.
Old 02-20-2017, 09:09 AM
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Car: 1967 Camaro, 91 z28
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Re: TBI 350 Halp!

http://easyautodiagnostics.com/gm/4....ed-icm-tests-1

I would suspect the pu coil or icm.
Old 02-20-2017, 09:47 AM
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Re: TBI 350 Halp!

Yeah, that's kinda where I'm headed with it. It's a slow process not having a lot of extra time.

Originally Posted by Tuned Performance
http://easyautodiagnostics.com/gm/4....ed-icm-tests-1

I would suspect the pu coil or icm.
Old 02-20-2017, 01:01 PM
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Re: TBI 350 Halp!

OK, got into it a little today, put the throttle body back on and checked grounds. Firewall ground was loose. I tightened it up, but it was still a little loose. Tried to start it, buddy said injectors were going, and it started on its own and ran decent. Shut it off because it was making an electricity type clicking noise near the ground. Pulled out the firewall ground, found a beefier spot, filed the paint away and made a new ground that is tight. Tested for voltage, and it's good. Now it's back to just turning over. Now what?!
Old 02-20-2017, 01:18 PM
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Re: TBI 350 Halp!

Do you still have spark, injector pulse ?
Have you checked for vats codes ?
Old 02-20-2017, 02:18 PM
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Re: TBI 350 Halp!

No injector pulse...just checked. Will try for spark a little later when I have more time. As for codes, I don't have an obd1 reader to be able to check. Thought we had one, but can't find it. I've been wondering if vats was causing an issue, and I've tried to resistor trick, but it actually threw the car into security mode.

Also, check my resistance and I have .3 ohms between firewall and throttle body, so guessing ground isn't an issue anymore.

Originally Posted by Tuned Performance
Do you still have spark, injector pulse ?
Have you checked for vats codes ?

Last edited by Vorexis; 02-20-2017 at 02:20 PM. Reason: Added info
Old 02-20-2017, 07:04 PM
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Re: TBI 350 Halp!

Use a paper clip and jumper a to b at the aldl.
http://www.obd-codes.com/faq/read-gm...codes-free.php
If it comes up with code 53 you have a vats issue.
Old 02-20-2017, 07:51 PM
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Re: TBI 350 Halp!

Oh, now that's neat. Thank you!

Update: in my tune up journey side of fixing this turd, I pulled the ICM to have it tested, and it showed bad. Hoping a new one will fix my problems and I'll have a running car by this time tomorrow evening. Thanks for the help! I'll report in tomorrow evening.

Originally Posted by Tuned Performance
Use a paper clip and jumper a to b at the aldl.
http://www.obd-codes.com/faq/read-gm...codes-free.php
If it comes up with code 53 you have a vats issue.




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