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I was given a 1986 GMC Suburban 2500. Don't know anything about it. I have a couple of questions....
First question: my father in law seems to think there is an ALDL connector on this to read OBD. I pulled everything out from under dash trying to find the ALDL connector. Nada. A friend says they didn't start with the OBD on these until 1987. Can anyone confirm?

Second Question: This has dual exhaust. Failed emissions. Twice the limit for CO at idle. No Catalytic converter. Could this be the reason? Did they come stock like this?

Third question: Towing: says it has 350 engine and 4:10 gear ratio rear differential. Will this tow a 7500 Lb. Travel trailer?

Fourth question: Hesitation when throttling, even dies when the least bit cold and throttling. Carb Overhaul? Any tips in the carb rebuild?

New to the group, looking to have some fun working on this. Any help is appreciated.

Thanks,
Matt
 

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Your friend is right, they didn’t put the OBD in until 87.


Our 86 has a catalytic converter but it is only single exhaust. So if they replaced the system with duel exhaust they may not have put 2 new converters in, they are costly, about $100 a peace for universals at NAPA.

I don’t see why not. Haul the trailer I mean. just make sure the brakes are in good working order on the trailer.

Carbs are funny things, if you rebuild it, it may work or not.

I have been rebuilding them for years, sometimes it works and others it doesn’t. the Rochester carbs have a lot of parts and are prone to problems.

I replaced the one on my 79 plow truck with a edlbrok (SP) and haven’t had any problems with it in years. It is more costly than a rebuild kit, but if it doesn’t work a couple of hundred for a brand new card isn’t bad.
 

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Thanks Fiero

The trailer is only 4 years old. it has good brakes..... Just need to install a brake controller on the burb.

I feel ambitious. I just may try my hand at the carb rebuild. it is an edelbrock. worse case scenario, it doesn't work, I box it up, send it to my father-in-law.....

looks like I am going to have to put in two catylitic converters since it is a dual exhaust.

Thanks for the response!

Matt
 

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Cat's thru Summit Racing are around $60 ea.

Check all the vacuum lines and timing first. Also a little carb cleaner couldn't hurt either. After the motors up to normal temps, I'd do a vacuum check just to see.

Before you have it tested again, make sure you've driven it at highway speeds for at least 10 minutes.
 
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