I have a 1981 Toyota 4x4 carbureted. Longtime viewer first time post. So heres my problem, No toyota buddys can figure it out. Here it goes, so after a few minutes of warming up/ driving when i get on the gas more than just a little, the engine drops down to idle, and sometimes it drops lower and will die. most of the time i happen to have my foot on the gas and in gear when it acts up, my engine rpms will kick up and down between idle and wherever the throttle is at the time. This causes insane amounts of bucking and jerking to where im just waiting for my Ubolts to snap :/ At first it happened randomly and in quick bursts only at high speeds, and now its to the point where it does it all the time mostly between 2nd n 3rd gear. So it seems as if its not getting spark intermittently but i dont understand how it drops back to idle then? lately it seems sluggish like a misfire all the time then it gets progressively worse till it has an episode. im thinking its the computer but not sure. Ive replaced the alternator, battery, voltage regulator, O2 sensor, Cap n rotor, plugs, wires, fuel filter, air filter, rebuilt the carb cuz thought it might be the problem, seems thats not the case. Please Help me Yota crew, its my daily driver and wheeler ive gotta fix this ASAP.

 

take the gas cap off and drive it around, see if that helps. sometimes the tank vent will get clogged and slow fuel down drastically until the vent has enough vacuum to pull through, wich will let it run well then slowly build up negative pressure again..

 

if that is your problem, an easy fix is to drill a small hole in the gas cap. or you can clean out the vent tube but that can be a hassle.

 

i would pull the carb again and check the float seat and jets and everything. i would start with the fuel system. pump, tank, evap., carb (internal parts and adjustment), lines.

 

check the coil at different temp. values. check for good spark. Kev

 

I cleaned and checked around 10 grounds and wires today and cleaned all the throttle linkage. checked all vaccum lines again. it does have 3 plugged vac lines i think the fed. ones it came like that and it hasnt been a problem i think it runs better w/ em plugged. Oh on note i found a really thick wire thats coming off the motor mount, one end goes to another wire that grounds to the body. does the end not connected go to a clip on a pump or the frame? ill check all the others tomorrow and get back to you guys. i also kicked up the idle speed and it bucks way less, but still dropping rpms. Ill try to check everything from replies. Thanks fellas

 

I would check the Emission System operation. When you start up the truck cold your settings, throttle position, ignition advance, etc. are controlled by the Emissions Computer through various VSV's, temperature sensors, etc. When the truck warms up your idle changes due to choke unloader operation, ignition advance change, etc. Check all of your Emission System component operations, vacuum hoses, fuel tank vapor control, etc. The Emission Computer / system affects driveabilty at all speeds.

 

Sounds like the carb.Start it and spray carb cleaner around, and see if you have a vacc leak or intake leak also.

 

you can eliminate computer, the only way you have a computer in that truck is if your dell is sittin on the passenger seat.

 

check the ground going to the fuel cut soleniod on the pass side of the carb.fuel pump diaphram could be bad mine would run fin then when it got hot would stall out and make the engine buck

 

All the time when it got warm or only sometimes? I've still got a problem similar to the OPs but mine is intermittent. Did it with 2 different fuel pumps though...never with the OEM pump, but then I only put a couple thousand miles on with the original pump so it's hard to say. Been going with Napa since then. I still need to check the fuel cut solenoid and yes you should definitely check that too! It's solved a few peoples problems who had issues like you're describing.

That could be my issue. I had the carb rebuilt by professionals, but I sure doubt they replaced the fuel cut solenoid, especially if it tests out ok. But my truck is sometimes fine, but does regularly stall when I restart it after being warm, so it could have tested out ok even though it might be malfunctioning. I'm very close to just buying a Weber...Especially since I know some of my emissions stuff is plugged up and you can't even get it from Toyota anymore.

 

it would run fine when cold for about 5min then when engine got up to temp it would not stay running unless you kept your foot on the gas.ran a new ground from the solenoid directly to the battery truck stopped stalling out.i have about a 45 min drive from work to home first i get on the freeway then drive up an arterial in stop and go once i was in the stop and go traffic the fuel pump would start cutting out and make the truck jerk and lurch.changed fuel pump problem went away.this was on my 2wd 22r carbed 81 longbed.at least this was my experiance with this problem.

 

Ok. Mine sometimes does it and sometimes does not. Almost never does it in the winter, only when it starts getting warm, so it's likely something else on mine..

 

now that i think about it the solenoid worked in the winter time but got worse in the summer so it may still be the culprit.step up to a webber you will like it it has mutch better throttle response i know they are expensive.i got a 38 and it aleviated allot of my problems

 

Yeah...what are they $250? Unless I buy some more diagnostic equipment (a good idea anyways, I know...), I'm looking at $75 for a local carb guy to do a full diagnostic, then I'll need to fix whatever's wrong...or just pay for the Weber (I think I'd get a 32/36) and call it good...plus get rid of all my clogging, expensive emissions stuff...although I know I can pull most of that and still have the Aisin work fine.

Anyways, I'll stop hijacking now. Thanks!!

 

oh yeah i would recomend getting the 32/36 i think the 38 is to much carb for the 22r without rejetting after i change my gears i will prolly start working on that mine bogs down pretty good and i think its the webber.works great but i suspect some of my power loss is the jets are to large.and if anyone gets a weber i also rec doing the overflow mod to it mine stalls on long hills.that mod is on the list of things to do

 

There is a computer module on all 1979-1983 Toyota USA trucks. It is located on the driver's side upper kick panel. It controls the Carb, Carb and Fuel tank vapor system, ignition timing (Calif.), etc. Canadian trucks have a computer mounted in the same location but do not control as many functions.

 

Hey guys so I tried driving with the gas cap off, made no difference.
Also im almost positive its not the float or carb internals, cuz it was doing it before the rebuild.
So when im testing the ignit. coil do i just keep checking for spark while it warms up?
And how do i test my computer/ECM? i have a feeling thats wat it is, i do tend to kick it sometimes when wheelin, ya know cold hand, heavy foot Haha. Umm ill also check the FICsolenoid and ground. Any other ways to find a carb/vac leak? Mine is pretty beat and the intake is Not exactly air tight. Missing nut here, no clip there, etc.

 

You need a service manual for your truck. Under the Emissions section, each function of the Emissions System /Computer circiut is described, system / component vacuum and electrical diagrams are included and testing procedures for each component is shown. In addition, the electrical wiring diagrams in the rear of the service manual show the Emissions Computer wiring.

 

i think that that is the fix to his problem. i hope he tries this. thats the first thing i would do. had similar problems in the past and that was the fix.