b2000 running poorly

Im working on a buddies B2000.

It has this bizzare problem lately (it started after another friend "rebuilt" the carb for him). It will run fine, idle at about 800 rpm, and then it will slowly rev up until it hits about 2000 rpm, where it kinda bounces around. It runs fine and such, its just revving high, until you hit the brakes, where it slowly loses rpm's till it dies.the motor was rebuilt about 3 or 4 years ago, and has had no real problems since. its stock except for a pace setter header and an aftermarket muffler of some flavor.

heres what ive tried to solve the problem. -I swapped on another carb that i know to be functioning correctly (it was off a running truck)-I swapped back to the original carb and eliminated all the smog silliness(capped all the vaccuum lines and double checked that I didnt miss any)-swapped back on the known to be good carb (this time with all vaccuum stuff off and capped)-I replaced the inake manifold gasket.-I unhooked and capped the vaccuum assist for the brakes.- I took off the valve cover today and ran it, everything appeared to be fine. I confirmed that the head was torqued.

Im at a loss now. none of the things I tried above made any difference at all. It continued to behave wierd fashion thru it all. Experience has taught me that when theres a problem, undo the last thing you did, and swapping on a good carb should have fixed whatever was "rebuilt" on the original carb.

Does anyone have any ideas?

Dave

you may want to check the fuel filter or pump. i know it sounds like a long shot but you could be getting irregular fuel pressure from one of the two making the needle and the float to get confused in the carb... a long shot but a thought.

I forgot to mention we also replaced the fuel filter with a clear one, and it appears to be getting consistent and sufficient fuel flow.

well you definately went in the wrong direction by capping all of that "smog sillyness" that is actually part of the feedback system on your carburator and it will now run super rich get poor gas milage and plug your cats pretty fast. Your best bet now is to just get a weber that doesn't require a feedback system because it will be nearly impossible for you to get everything hooked back up right. For all intensive purposes NEVER PLUG ALL OF THAT STUFF GOING TO YOUR CARB ITS NOT I REPEAT NOT SMOG STUFF IT IS NESSASARY

have you checked the a/c idle up system?

only problem i came into after pluggin my smog shit was that it ran a lil richer. best bet is to go and get a weber. i got my first one from a junk yard, it was off a volvo. paid $15 for the carb, had it rebuilt for $25, then like another $40 for an adapter plate and linkage.

when you capped off the brake assist was it at the engine side or did you just stick a bolt in the end of hose? it sounds like a booster or brake vacuum line leaking.

The truck doesnt have A/C.

I plugged the vacuum assist at the manifold (i even used an official vacuum plug).

And i plugged all the vacuum stuff trying to eliminate that end of the system as a potential problem. Running rich is a far better problem than being undrivable.

A Weber is in the future for it, but why dump the money in it if the carb isnt the problem. (which, we know it isnt the problem being that the issue persisted with 2 seperate carbs)

but a brake booster/brake problem shouldn't make the truck go dead I had the brake booster go bad on my truck and it took me about 2 months to figure out that it was the brake booster I couldn't hardly get over 40mph with it and I destroyed 2 sets of rotors 3 calipers and 2 pair of brake pads. All of this because I didn't realize that a brake booster going bad could apply the brakes I always thought that it would just make braking harder anyway I don't think your problem is with the brakes. I do think it could be your clutch master/slave cylinder. good luck with it I hope you don't have as much problem as I did with mine

you have a big ass vacuum leak, that only happens when the engine is warm.

thr idle speed increasing, that is from extra air being let in to your rich running carb.

And running rich is NOT a great idea, even for a little while. Rich running cools the exhaust temp (you are spitting raw fuel into your cats) and washes the cylinder wall (you will wear the bores.rings out in no time flat).

Cheak the carb base, it may be warped. If you are not using a new gasket under the carb that is probably where your leak is. When it idles up, try revving the engine. If you get lean barks, you have a big ass vacuum leak.