Al's Chop Shop

the last 2 weeks the 81 has become my DD and i'm starting to notice some weird quirks. it seems the choke stays on way too long. and when its on, it seems to run on the rich side. when starting if its only half warm and i bump the throttle any more then to set the choke it will flood. when its 100% cold it hesitates under medium throttle, again... thinking its rich. the choke doesn't kick off until the truck has been at full operating temp for quite a while, then if its off for just a few minutes it kicks onto partial choke even though its hardly cooled down much (though the alum radiator might have a bit to do with it cooling down so fast). my idle is a little rough, and it also stalls occasionally when coming to a stop after full temp and the choke is 100% open. it might just need to be bumped up a bit, but i want to make sure my mixture and choke are right before i cover symptoms up with the idle speed.

any tips on getting this to run a little better? this is a brand new (<5k miles) aisin carb.

Al

cdg

The joy of carburetors. The first place I would be inclined to look is in the vacuum hoses - you might have a cracked line somwhere or something could have been accidently hooked up wrong during the reassembly process.

It could also be a faulty vacuum pulloff. Or on some models I think you have to bend the linkage from the vacuum pulloff...

Then I would examine the fast idle cam and its adjustments. There are 2 (correct me if I'm wrong) small flat head adjusting screws that control fast idle cams - they also can affect how well the idle kicks back down though. You should make sure that the choke plate is set with the correct gap too - specifications vary from year to year. usually not more than 1/8" gap. You test the gap with a drill bit shank. Some are non-adjustable and riveted - riveted models shouldn't ever drift out of adjustment but not every reman company is as careful as the should be...

Lastly the choke thermostat could be faulty. There may even be an adjustment on some models. You should go through the choke system in your shop manual to get the detailed procedures.

Al's Chop Shop

do the fast idle cams adjust the speed of the idle, or duration it is used?

Al

cdg

Speed of the idle. When the fast idle is set too fast though it can make it tricky to get it off fast idle (normally knocked down by sweeping the accelerator once).

It sounds more to me like you have a fulty vacuum pulloff, maybe another vacuum issue... Possibly a choke thermostat. On some models the choke Tstat is adjustable. The bimetallic switch that sets the choke is also responsibile for setting the fast idle. If incorrectly adjusted, it can activate the fast idle cam without fully activating the choke. At least this is possible on a 1980.

83toy4x4509

Ok sence were talking about carbs mine is kinda doing the same thing but cold start it idles at 1200 fo about a min or so then it gose up to 1900 about and idle there so it's warm now I drive away and stop it dies hard to start again but dose then when warm it will stay at 1100. I sometimes have to sweep pedal so it won't die and today I notice gas leaking from the little diagram thing on the carb if u push it pumps fuel in to carb would that have a effect on my idle and ect but I don't know what that's call were it's leaking but I need to fix it soon