22R carb float gas level drops overnight?

On my 1984 Toyota pickup, 22R engine, the float gas level is right where it should be (middle of sight glass) when it's running and right after shutting the engine off. But after a few hours, and
especially overnight, the gas level drops down to the bottom of the sight glass, just barely visible. At that point it takes 15-20 turns to get the engine to start. Once it starts and runs, then it will always start on the first or second turn until that point that it's been shut off for a while.
I checked the vent control device and it's plunger is free and working correctly as far as I can tell. I'm not sure where else to look...I don't see any evidence of gas getting into the oil but if that happens, what path would it take to get there? This happens everytime I park the car for more than an hour or two and I use the car every day...so if gas was getting into the oil I think I'd notice the oil level rising and the oil smelling of gas, which I don't.
Any ideas about this...I had the same problem on my 1976 Datsun pickup except it took 3 days to reach this point and then it wouldn't start without starting fluid. Couldn't figure that out either.
jc
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wrote:

The gas is going to evaporate in the bowl, especailly when engine is hot. Your problem is not that but rather fuel supply because the fuel in bowl should be quickly replaced on startup. Check fuel pump, filter and maybe for a a restriction or vacum leak on suction side of fuel line slowing the draw of fuel from tank. ----------------- TheSnoMan.com
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Thanks for the idea, I'll check the fuel pressure and the filter. But if there was a problem in this area, wouldn't it show up as a lack of power under acceleration or at freeway speeds? And is it really normal for 1/4-1/2" of gas to evaporate in the float chamber...an hour after shutting the engine off, when it is the hottest, the engine still starts up easily. So the evaporation must be happening after the engine has cooled.
I agree that the fuel pump should be filling up the chamber immediately but here's another thing that's puzzling me: after the float gas level has gone down, it takes about 20 pumps to get the car to start. When you look down the primary venturi, there is an orfice (jet) that just barely dribbles out gas with each pump. Should this jet be showing a good strong squirt...or is it designed to barely dribble. On the cars I'm familiar with, old VW's, the accelerator pump nozzle gives a very good squirt with each pump. I wonder if part of the problem is in the accelerator pump area...or does this 22R carburator rely on another source of gas for it's starting charge.
Let me know what you think about this.
jc

it's
drops
been
take
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Possibly there's a needle valve in the bottom of the bowl? A worn valve would allow the gas to leak into the manifold. The gas should be visible in the manifold.

where it should be (middle of sight glass) when

hours, and especially overnight, the gas level

point it takes 15-20 turns to get the engine to

or second turn until that point that it's

correctly as far as I can tell. I'm not sure

oil but if that happens, what path would it

hour or two and I use the car every day...so if

and the oil smelling of gas, which I don't.

except it took 3 days to reach this point and

out either.

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This is possible but even still a good fuel system with a good pump would replace it quickly when cranking. He could add a eletronic boost pump to switch on before starting to fill bowl quickly if he does not find anything else wrong. If you do this you want a pump that is about 6 or 7 PSI max. I suspect the fuel pump is weak and while it can keep up with driveing demands it has little reserve and takes time to fill bowl. Also, it does no good to pump the gas pedal when bowl is empty. Wait a few seconds for bowl to start filling during crank than pump it. Try this, crank it for 4 or 5 seconds and do nothing, pause for a few seconds and then pump gas and crank it. ----------------- TheSnoMan.com
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Yes it should. Sounds like the accelerator pump is not working properly. It would be a good time to get a carb kit and overhaul the carb. Be sure to clean the passages and blow them out with compressed air.
.or is it designed to barely dribble. On the cars I'm familiar with, old VW's, the accelerator

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I checked the fuel pump and it's putting out 6 psi. I also tried some starting fluid and the engine started right up, and the float chamber filled up to the correct level very quickly. That leaves a bad accelerator pump diaphram or the accelerator pump jet plugged up as the problem. My air compressor isn't hooked up so I'll have to figure out a way to blow out the jet but I'll bet it's one of these two items. And my original concern about the float gas level may have been misguided. Someone on another forum told me that he checked his sight glass and his gas level was lower than mine and his engine starts right up everytime.
jc

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starting fluid and the engine started right up,

leaves a bad accelerator pump diaphram or the

hooked up so I'll have to figure out a way to

original concern about the float gas level may have

sight glass and his gas level was lower than mine

Well, the accelerator pump will also drain the bowl if it's leaking. But there's also the "pump" aspect of it so I'd be getting a rebuild kit or a rebuilt carb. You need to replace it.
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I'm trying to find out which nozzle/jet/orfice discharges from the accelerator pump into the venturi. I think it's the one that shows dribbling gas when I activate the throttle arm (where the accelerator cable attaches)...it's a brass piece just barely sticking out into the venturi and it's in the front (front of car) wall of the venturi. You can see it looking down into the primary throat. My two manuals show all the carb components but leave out the standard horizontal drawing that shows the passageways connecting between different parts of the carburetor. Does anyone know of a web site that would have that drawing for the 1984 Toyota pickup, 22R engine. I have a manual that goes up the 1983 and has this drawing but it's the wrong carburetor.
I want to blow this jet out and I'm not sure if it comes directly from the accelerator pump...can I just remove the accelerator pump diaphragm and blow through the little hole?
jc

it's
take
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Been there, done that. I have an '82 with likely a very similar Aisin carb. Find a NAPA and get THEIR aerosol carb cleaner, two bucks. Best cleaner I've ever used, a total carb rebuild with it and an old toothbrush. Anyway attach the little tube and squirt it through the little hole and see where it comes out. Do those on top of the carb body too and see where they go. Watch your eyes! BTW, NAPA sells an accel. pump singly should you not be up for a rebuild. (Wish'd I'd never dis-assembled the choke assy or throttle linkage, there was no need to). my 2 cents...

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I tried blowing through the accel pump passages with carb cleaner, the larger of the two holes goes to the float chamber and was clear, but the smaller hole (on the left side) didn't seem to be clear and I didn't get anything to blow through and out into the primary venturi. If there's a check valve it should allow pressure to go through towards the venturi...but that's something I don't know. In fact, I'm still not sure where that passageway leads...do you remember from when you did it. The diaphragm looked old and a bit stiff, but I couldn't see any holes in it.
So my quest goes on, to find a diagram of the carburetor passageways...anyone out there have one? Does anyone know what supplies the first charge of fuel that actually starts the engine...which nozzle/jet in the venturi does it come out of and does it come from the accelerator pump or from somewhere else? You wouldn't think this information would be so hard to find.
jc

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Its been more than 2 years but I don't remember any check balls. The stiff diaphram may depress and make a pump okay but the light spring may not have enough oomph to return it back to position, if all the way . Do remember mine being really stiff, NAPA $8, but a rebuild kit was only $30 out the door. With that said...
Try from the top of the carb the same cleaning method on all the holes...will PM you...

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Sorry, tried to PM with the rebuild drawing but server setting wouldn't let me for some reason.
I don't work for napa but was recommended their cleaner, robin's egg blue spray can was only 2 bucks. Used 1 can for rebuild and bought another later just to have. it has xylene and acetone in it. also had Gunk on hand but it hardly did a thing except stink. Had real good luck on general cleaning but gave it good blasts on those passages. The truck sat for 2 years and the carb just filled with deposits, nothing worked and of course no fuel, no run. Now at zero degrees on a cold morning it starts in 2 revolutions. I now use two fuel filters inline, the old standard cylinder type and did away with the expensive stock type.
Honestly you might try a rebuild kit. The choke, and butterflys dont need to be messed with. In hindsight I wouldn't chang the float needle SEAT either. You really want at the main body to do a good cleaning of the ports and there are some more ports on the underside of the main body.The carb might seem intimidating by looking at the drawing, but looking at the actual parts involved it really is quite simple. Will attach the repair sheet. 446k. Will note that these carbs seem sensitive to float levels, just change the needle? Mine sits right at the top of the sight glass. After trial and error that's where it wants it. My mileage is 2mpg better than before and starts like a dream. And it is normal for boil-off/evaporization to happen if left sitting for a few days and will have to crank for a few seconds.

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mercury...where did you attach the repair sheet, I'd like to see it...
Here's my eemail... jbclem1 "at" charter dot net .
Thanks...jc

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will re-attempt. i think it just worked, pm'ing you. couldn't even send the dwg to myself, but after opening ie was able to...figger that...

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