dbender

I've got a puzzling fuel problem. My 87 toyota truck carb bowl will drain into the throat after the truck is shutoff. Fuel is midway in the sight glass. Truck runs fine until you shut it off then bowl will empty into the throat and fuel pump will not refill bowl until it sits for a while. This is an intermittent problem that occurs hot or cold. I removed the fuel tank to make sure there was no trash or obstruction (perfectly clean). New fuel filter, new fuel pump. Nothing has helped. Sometimes the carb seems to load up and run rich but will smooth out after a few minutes. This truck runs smooth as silk and idles flawlessly most of the time. It's as if the bowl is becoming pressurized somehow? The bowl vent is clear. I've disconnected the charcoal canister with zero effect. I disconnected the secondary accelerator pump also. I have no idea what else to try. Any suggestions are welcome.

slow-mo

It's a common problem. I also had it on my '87 22R. In my case, it happened after a carburetor rebuild. Even after installing a new engine with a new (remanufactured) carburetor, it still did the same thing.

I went so far as to separated the three haves of the carburetor, putting it into the kitchen oven for 20-30 minutes at high heat, so that the metal would expand (to simulate the heat in the engine compartment), then reassemble the carburetor while still hot.

I was initially thinking that when I rebuilt the carburetor at room temperature, when installed and the engine up to running temperature, the metal would expand causing the fuel to drain. But the oven procedure did not fix it.


There was one person here, about 2 years ago, that bought a Chinese remanufactured carburetor on ebay, and that fixed his fuel draining problem.

L5wolvesf

You've worked on everything except the . . . carburetor. The part where you say it "seems to load up and run rich but will smooth out after a few minutes" sounds like a sticking component like the cable or the throttle shaft. Has the carb ever been rebuilt or serviced in any way?

dbender

Sorry I wasn't clearer as to what I've already done to the truck. I've rebuilt the carb twice with two different aftermarket kits. Didn't help the problem. Slow-mo, did you ever fix your problem? I've owned this truck since new so everything that has been done has been done by me. No emission/vacuum lines are removed except for the secondary acc pump. I've changed the diaphragms in both accelerator pumps but didn't help. The truck has a ton of miles but has been well taken care of. Carb looks good to my eye can't see how a worn passage could cause problem anyway. If I crack the top half of the carb the fuel pump will immediately prime the bowl and start instantly. Choke is set correctly and works as it should. Float is set correctly and seems to work fine. Truck does not run at a higher temp than it ever did. Weird intermittent problem that may not return for months at a time? Thanks for the replies!

slow-mo

No. I just lived with it until I eventually sold it.

I also had my '87 since brand new. I was pretty much like you that I tried to do as much work to my truck as possible.


People on this board have said that they though the fuel was flowing backwards out of the float bowel through the fuel pump and back to the fuel tank, but they don't understand that that once the fuel is in the bowl, it physically can't return the same way.

My issue was like yours in that the fuel would drain down the carburetor throat body. The fuel would saturate the carb insulator.