1986 IROC 5.0 TPI auto.

There's exhaust gases being pumped out of where the AIR tubes join the exhaust manifolds. Also, the temp gauge makes a beeline for the top and stays there.

Theory... clogged catalytic converter. But there still is exhaust flowing out the back. Perhaps not enough? Partially blocked converter?

Theory... bad check valve causing the system to not pressurize properly. I don't know enough about emissions equipment to tell.

Theory... bad AIR pump. Again, I don't know enough about these things to tell.

I need to get this car back on the road, the fuel economy in my truck is killing me. Someone please advise.

Bry

 

Sounds like the exhaust system is plugged up. Check the Cat Converter and the muff. I have not given this much consideration but these are the only reasons I can think of why you would have so much back pressure in the exhaust system and the engine is heating up so fast......

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"84Z28/'91 305TPI comp cam flowmaster TB coolant bypass/shutoff valve to heater core MAT relocated Ram-Air(home-made) gutted air-box IROC ground effects/wheels GY245/50's 700R4 superior shift kit/ corvette servo(excellent shift kit BTW) Rebuilt engine and transplanted it myself. Love this engine!
LOW performance people should drive low performance vehicles!