I live in CA. The carb on my '84 PU will either meet SMOG regs or run well, but not both. Every other year I go though the reqd SMOG test and always fail. I have the carb adjusted to meet the requirements and its studder and snort all the way home. Is there someone out there that really understands the "computer controlled" carb on this engine and can give me some direction to move forward, other than sell the truck? I believe it is a Rochester 2SE but the name is a guess. Thanks for any help.
I replaced my 85 c-10's 250 with an ATM rebuilt from 1984 and discovered changes in the "air emissions" system from the two years. The truck also needed a rebuilt carb. Like yours, mine hesitates especially when cold and fails to meet my expectations when warmed up. I have not encountered a "computer" on my system yet. There is a hard to reach (find) choke/idle adjustment which requires a special tool on the carb. Due to the various systems GM used that year for exhaust emissions, I have to have my truck inspected by DMV because the boys at the commercial inspection stations can't find my particular tubing arrangment in their books. Luckily in NC, if you spend X amount of dollars on a "classic" trying to meet exhaust standards and still do not, DMV will overlook the problem and issue a sticker. Which puzzles me, how do these guys who drop 350's in those old trucks get the emissions approved? In NC they check the actual engine set up and if it's not stock, you lose. BTW, what kind of gas mileage do you get? I'm thinking this 6 is getting about 10 miles to the gallon.
Thanks for your reply. I guess GM was trying to make the carb work and then gave up and went FI all the way. We do get to go by the test after spending $400 but this seems high to me. I get about 12 to 14 mpg depending the trip. Really it runs pretty good after I have it richened up after the smog test. I have to go, Superbowl Party, thanks again..more later.
The GM computer controlled carbs worked great when everything was new,unfortunately when somethings a little out of adjustment or worn they get hard to tune.Have you tried replacing the mixture control solenoid?They sometimes get dirty and don't work right. Craig Hager tech1@chevyduty.com
Just some feedback. I had the carb rebuilt and that cost some $. It ran OK from the carb shop. Next I had it smogged and same old problem, it hardly got home. I replaced the spark plugs just to be sure. No change. I went to the carb shop and they checked it and the smog tester had closed two manual jets completely. He adjusted them and all was well again. It was rich because I could smell it. Next I replaced the O2 sensor for $25 and its easy to install. WOW, now it runs great. Best thing I've done to it. I have two years until the next smog test but I think I might just pass. The check engine light qut coming on too. Hope this helps others. If anyone has a complete tech manual on the CA Chevy 250 emissions sytem I would like to get a copy. I do not think mechanics know how to work on this old truck.
