fyrfytrryn

hello everyone.
1985 toyota 4x4 pickup with a manual trans. odo reads 329,000 (newish motor).
the truck starts, idles, and drives great until you press the accelerator more than 3/4 way. After that it kind of stumbles and loses all of its acceleration. when reducing the throttle back to 3/4 or less the truck continues to accelerate normally. if i just kind of cruise the truck and never push beyond 3/4 i dont notice any issues. but full throttle efforts result in really poor acceleration. almost seems as if its not getting enough fuel, or too much? i dont want to tear into the carb just yet and i wanted to know if anyone has had this issue and how it was solved. some have suggested a bad/weak coil, choke not opening, ect.
thanks in advance everyone.
ALSO: i read quite a few threads as well as the info on blue bass design's site. nothing mentioning this issue they mostly speak about low end or around 2000rpm. my issue is high rpm over 3/4 throttle.

ojm3

stock carb? I had the same problem turns out my secondary butterfly froze shut. check your gaskets where the intake meets the carb and where it meets the engine block. actually I'd just replace them. if your getting stumble at 3/4 throttle and none at 1/2. your probably pulling extra air through the gaskets which disrupts your fuel flow pattern which cab cause poor performance.

fyrfytrryn

yeah it has the stock carb. interesting development, yesterday i tried really easing into the throttle. if i really ease into it, i can get the truck to go WOT and act normally (rev high and produce torque) especially downhill it almost acts like a bogged down 2 stroke, once i feather the throttle wide open and it "cleans out" life is beautiful. so if i really feather it from 3/4 to full its great (depressing over 5-7 seconds), its trying to rapidly get on the gas (depressing 1-2 seconds) thats causing the issue. the intake gasket is near new, but ill check the carb to intake gasket. i bought a rebuild kit, but ill probably just save it for when the truck really runs like crap. i dont want to make it worse.

ojm3

If your having carburetor trouble just rebuild it now and get it over with. It probably needs to be done anyways, it'll run better and you will have eliminated all carburetor suspicion. I had the same problems as you, turned out i had a secondary butterfly frozen shut. so i replaced it with a weber. Still same problems, bad idle, horrible cold starts, lost all power at WOT, only seemed to run good when i eased into the throttle. So i rebuilt the carb, replaced all the internals, same problems. I then went through and replaced all the gaskets and used hi tempt permatex "orange/red stuff" BAM BABY all problems gone, shes a hoss now!

BHMECH

What gaskets did you change? The carb gaskets or intake? I have a similar problem, I rebuilt the carb because it wouldn't idle right, still wouldn't idle. replaced the engine computer with a 2wd computer all the problems but this one went away. I couldn't find the California 4wd one! Then bought a rebuilt carb. from a local LA carb shop. No change, I thought it could be a restricted exhaust, so first disconnected at the muffler, then at the manifold and the problem still the same. Went back to the carb shop convinced it was in the carb. They were really good about it and built me another carb. put it on
Same thing!

ojm3

Check your intake manifold gasket. Check all your egr stuff. I blocked mine off after i noticed i had been sucking sure through worn gaskets

scottt80

I'm having a similar issue with mine... I read on another site that it could be the fuel pump can't keep up when going full speed.