Hello everyone, I recently picked up a one-and-a-half-owner survivor from the grandson of the original owner. Truck was parked in a barn most of its life and thus has pretty nice original tan paint, 60k original miles, all maintenance paperwork, and even dealership documents. It's a 1980 long bed with a stock 20R motor and probably the worst set up ever (2wd, automatic transmission, and low). I drove the truck 80 miles home from where I bought it with no issues (even up hills with that automatic) except when I came to a stop, where it likes to stall unless I really feather the brakes, or pop it into neutral. Grandson had unfortunately removed all the stock vacuum and smog equipment, but kept the stock carb (designed to implement all of those things to run correctly I know). The unused vacuum ports had been blocked off with pieces of cracked hose and golf tees, and someone had pulled of the carb earlier without replacing the carb-to-manifold gasket, so needless to say I thought I just had a couple vacuum leaks to fix. Well this weekend, with a little bit of starting fluid, I found out it was sucking a lot of air at the base plate of the carb, so I removed it, cleaned it up, added the new gasket, replaced cracked hoses, and I blocked off all the unused vacuum ports properly. The carburetor is no longer sucking air from anywhere that I can tell, but I'm still having the same issue of stalling at stop lights unless I feather the brake or pop it into neutral. Adjusting the idle set screw to the point where it idles smooth, makes park and neutral idle way too high. As this weekend draws to a close, my plans for next weekend are new fuel filter (where is that located on a 1980?), new cap/rotor, new spark plugs and new ignition wires. Assuming I do not have a vacuum leak, am I on the right track to a better idle and no stalling? The truck does not hesitate, even for a moment on acceleration or cruising, just at stops and idle. (Gas must be pushed down about a third of the way to start as well) Is it time for a Weber? This issue would not be such a big deal if the truck was manual... Anyhow thanks for looking.

 

I remember messing with some vacuum hoses once on a similar year 20R truck. I unplugged one of the hoses and it did the exact thing you are describing, so it is definitely not tune up related. It is something controlled by one of the vacuum hoses. You might be able to fix it by wiring the fuel cut solenoid directly to the ignition so it is always on when the key is on. If you look at the vacuum line diagram sticker on the bottom of the hood and test some of the ports on the carburetor, you should be able to figure out which lines pull vacuum only at idle. Hooking those back up would more than likely fix the problem. If smog is required where you are, then you are going to have to hook all of them back up anyway.

 

Best thing you can do is de-smog that thing. Get a Weber carb and an exhaust header, eliminate the EGR valve, smog pump and all those vaccuum lines. I havea 1980 4X4 with a 20R and that''s what I did.It was doing basically the same thing, would die at every stop sign. I bought it used with 140K miles, guy I bought it from said the carb needed rebuilding but it had so many vaccuum leaks, it wasn't funny.

 

I spoke with a Toyota specialist where I live in central Washington (smog/emissions systems not required), and he says this is a common problem and it is almost always a specific solenoid (can't remember the name, perhaps this 'fuel cut' solenoid is the one he was talking about). where is this located on the stock carb? I only have one set of wires connected to mine and that's the electric choke I think...

 

It has been a while since I have worked on 20Rs, but I believe the fuel cut solenoid is the only thing with electrical wires attached to it on the carburetor. The choke is controlled by engine coolant.

On my 22R, the fuel cut solenoid cuts off fuel to the idle circuit of the carburetor both when the engine is off to prevent dieseling and under certain deceleration conditions to prevent overheating of the catalytic converter. I assume it is the same on a 20R. Just something to keep that in mind if you wire it straight to the ignition switch.

 

The fuel cut solenoid is on the back side of the carb toward the firewall. As supernerd said, it cuts the fuel off during deceleration to prevent overheating the exhaust system there is a vaccuum switch in the fuel cut circuit also. If you are not going to de-smog it, I recommend you invest in a Chilton manual. It has pretty much all the info you need to repair and maintain your vehicle. The Chilton number for the manual is 68600, covers 1970 through 1988 Yotas. fuel cut solenoid is in section 4-18