Need help!!!

Hey everyone. I am working on a 1986 B2000 that is having a weird problem. I was wondering if any of you have had this same thing happen and what turned out to be the problem. I start it up, it starts a little smokey(doesnt appear to be blue or black, just smokey), aftre about 2 or 3 minutes, it runs fine... idles with no problem. Drive it down the road and after about 10 or 15 minutes, it starts to stutter and bog down if you try to put any load on it. Still idling fine. 3 minuted more and it has no pwer and you have to pull off the road. The temp gauge is normal and the engine isnt overheating, but the exhaust is red hot!!. After it cools down, it'll run fine again, but the entire scenario starts again. For those who are mechanics, it is carbed, and the cat is still in, and it passed WA state emisions earlier today.......???? Help!! Thanks, Sponge

Bump... just to get some help. Any ideas?, Thanks.

sounds to me like the cats pluged up if it is bolted on like my nissan than take it off and take it for a run and see what happens if it runs fine without it thats your problem hope this helps

Edited: 12/11/2008 11:22:21 PM by UnusualFabrication

I was going to say the cat too......

Hey Sponge...

What part of the exhaust is red hot?
Any unusual engine noises?

I would look at the cat: disconnect the cat from the exhaust manifold and try driving it, it will be loud!

Thanks for the help guys. Clint, the exhaust manifold right where the O2 sensor goes in is what gets red hot. Its hard to see how much gets red cause its covered with a sheild, but we put a lazor temp on it and it said it was 980 degrees. The lower portion of the exhaust pipe read at about 600 degrees. I am going to get a pic of it and put it up later. Then I will disconnect the exhaust and see if it runs better. Does every on agrre with it being the cat. I talked to a mechanic and he said that it was "because the carb is stuck and it is running to lean". Doesnt make sense to me unless somthing was compinsating and it was just flooding it with fuel. The other ideas I had was maybe a stuck exhaust valve, or a bad computer. I don't know!!??? Sponge knows dents!!,.. not engines!!

Any body have any other ideas. If any of you guys hang out on the Mazda forums, could you ask around. Thanks.

+1 more for the cat being pluged. Running bad and glowing red is a good sign its pluged up. if you dont have to pass emisions you can either get a pacecetter header or pull it apart and knock out the guts of it. If you do I dont know how it would smog if you knock the stuff out.

crank it up and see if there is even any pressure coming out of the exhaust. if you feel nothing or very little pressure, than there you go. is the carb a stock carb or aftermarket? if it is an aftermarket, make sure that your primary and secondary screws haven't backed out or anything. your exhaust is going to glow for one of two reasons, your cat is clogged (which it probably is) or you are running lean. those things have 2 cats on them. 1 is bolted directly to the manifold and the other is under the cab. if it is glowing at the manifold and not further back, i would unbolt the first cat and punch out the guts. bolt it back up and test it out. i would not suggest running it with the exhaust completely unbolted you can burn up a valve very easily on these little engines, they need the back pressure to operate correctly. let us know how it turns out.

its gotta be the cat. its prolly stock which means its 22 years old, everyone says replace them every 10 years. unbolt it and knock that junk out of it.