SCToy

So, I've been trying to solve this with no luck.

About a month and a half ago I was driving and hit a pretty big pothole. The emission control box in the driver's side kick panel separated from the mounting bracket and fell down. When I pulled over to put it back. The truck would no longer idle, completely loses fuel when I take my foot off the gas.
There are a few other symptoms.
When I start it up, the charge and sensor light stay on indefinitely until you hit 2500 RPM. If you rev it up fast they go off, but they will stay on until you hit exactly 2500 RPMs and then go out with a relay sounding click.
When I took the air cleaner off and started it up and gave it fuel by the carb, I can see only one of the butterflies is opening, the other stays shut even at full throttle. When I let off the throttle it gets no fuel.
It runs a lot rougher now, as well and gets much worse fuel economy.

I've looked to see if any wires broke, but haven't found anything conclusive.
I got a second emission control computer, but that didn't solve it either.
If anyone can point me in the right direction, that would be helpful. Maybe the emissions control box I got to replace it with was broken as well? Or it is a wiring issue and I just haven't found which wire broke.

Any help would be appreciated.

slow-mo

First thing i can think of is to check the carburetor float operation. Make sure that the fuel level is at the correct height. Since the carburetor float is always in relative motion, it may have been jarred from the sudden and violent impact from that pothole.

If you mean butterfly valve at the top of the secondary barrel, then it will stay closed when the carburetor is only operating on the primary barrel.

Now regarding it still not working at full throttle, I would check that you can manually open that valve by hand. That valve is called an "Air Valve". It functions as a modified variable venturi since the secondary barrel has no venturi at all.

Wait...unless you mean that with the engine off that valve still does not open. If so, that that is normal as that valve operates only when vacuum is behind it. As when the secondary throttle valve becomes opened.

SCToy

Yes, the valve for the secondary. Doesn't seem to do anything with engine on or off. I can open it by hand though.
I did have a few vacuum lines off when i took the air cleaner off to investigate how the mechanism worked. I can try just removing the top of the cleaner and looking in while someone in the truck starts it up. I'll have enlist some help and get back to you on that one.

I'm a complete novice with the carburetor. This is the first time it's given me any trouble.

The warning lights staying on until i rev it to 2500 rpm points to some kind of electrical failure in my mind, but i could be completely wrong.

SCToy

I can see that there is no fuel without hitting the throttle though.

slow-mo

That valve won't do anything with the engine off. It opens via pressure differential between the vacuum created by the down stroke of the engine and atmospheric pressure above the valve.

Since the valve does rotate by hand, which it should, then there's no binding on that valve. I suspect, while the engine is running, if it doesn't open, that because the engine is not under load it wont open with just a brief blip of the throttle.


The idle jet is waaay down below the throat of the barrel. It's doubtful that you would be able to see the fuel coming out without a flashlight and knowing specifically where to look.





As you can see in the picture, the idle jet is past the throttle valve. The throttle valve will be open to a degree, but whether or not you'll be able to see fuel coming out is something else.


So, check the fuel level in the float bowl. A out-of-spec fuel level will affect all other carburetor circuits.

SCToy

http://www.toyotanation.com/forum/81...-solenoid.html

Post number 14 and some beyond that seem to touch on the problem.

I'll take flashlight and have a look and report back.

83Toyota88

iTrader: (1)

I would check the fuel cut-off solenoid as that thread mentions. Also might try tapping on the carb to try and free a stuck component from the pot hole hit.