1984 Chevy G20 van cat red

[82Stang]

Hello,

Chevy G20 van with a 5.8L I believe. It starts and runs fine for a few minutes then the cat converter get's red hot and it must be shut off. If it runs fine at first, could it be something other than a clogged converter i.e bad plugs/wires etc?

Thanks.

[MT-2500]

Yes check engine running.
Check timing and fuel mix.
How is the tune up end?
But also check cat back pressure engine running bad can block a cat.

[DFBonnett]

I had the exact same problem with an '86 Econoline. The carb was dumping gas. I couldn't find a rebuilt right away so I took a shot and rebuilt the carb with a Jiffy Kit, making sure to hose out all the little ports with spray carb cleaner. Amazingly, it worked.
FWIW
YMMV

[82Stang]

Thanks, I'll check the tune up first and go from there.

[82Stang]

Just a final answer to conclude the original post.

I pulled exhaust and opened the cat, looked like a cat. Ran it with no cat etc and it was sort of popping out the tailpipe and gaseous flames. The carb must be dumping fuel down it.

I sprayed a full can of gumout carb cleaner directly in the carb throttle bodsy all over. Now she starts and runs good for a minute or two and instead of almost dying out, it has some remaining sputter and idle, but much better than before. High idle and it opens right up and runs strong. So, could be dirty carb, bad egr or tps.

Is there a port to use my code reader on this thing or too old? My reader say's it fits this and I looked up and down for a plug under the dash and under the hood, no luck.

[DFBonnett]

Can't answer the code question but you may get good results spraying carb cleaner into the fuel bowl vent until it bubbles out the top. Some may have already gone down the vent in the general spraying you gave it, thus accounting for the partial amelioration of the symptoms. After concentrating on the vent, let it sit for a half hour and then start it up. Repeat a couple of times and see where that gets you. My best guess, like yours, is funky carb internals. Carb cleaner down the bowl vent should help if that is the issue.