RobW82400

Hey all, I have been trying to solve an issue with my 90 22R with Aisin carb running rich and smelling like gas when running.

I have rebuilt the original carb and replaced it with a rebuilt carb.

I have checked the AAP valve, it looks fine and have also disabled it by capping the vacuum connection with no luck.

I have checked the operation of the BVSV and it seems to work fine.

I have replaced the Thermostat.

The float level appears fine, a little below halfway but where it is supposed to be.

I notice fuel around the top of the carb as if the fuel is possibly coming out the top of the carb when I give the engine gas.

This isn't a 4X4, and this happens only while driving around town. The more I step on the gas the worse it gets, and it is worse after starting cold, but still noticable when warm.

Any tips or advice much appreciated!

Thanks,
Rob W

swampfox

you said that you have rebuilt the original and replaced with a rebuilt carb, so 2 different carbs are doing the same thing. just trying to get it strait.

RobW82400

Yes, both carbs are doing the same thing. The second carb was purchased rebuilt online, so I suppose it's possible both have the same problem. The reason I went with a second carb is that the original was supposedly rebuilt with a 'high idle kit' when we had aftermarket air conditioning installed, so I was thinking maybe the jets from that kit were causing my issue.

swampfox

does the engine run smooth ? does the choke open fully, any flooding? any back firing ?almost sounds like compresson coming out the intake.

RobW82400

It runs smooth, choke opens all the way when it is warm and hasn't flooded since I rebuilt the first carb. Doesn't backfire. There is some darkness to the exhast smoke, especially when it smells stronger.

Compression out of the intake... dunno.

There is a plate (not sure what it's called, sort of a spacer the same shape as the bottom of the carb) between the carb and intake manifold that has the carb sitting about a half inch higher than it would otherwise, not sure if this piece was stock with the truck or if it could be causing my issues.

swampfox

if it runs good it probley not a compression issue. the spacer plate is suppose to be on it. it sounds like it is flooding a little if it is putting out black smoke sometimes.

RobW82400

Thanks for the replies Swampfox, I am guessing that my rebuilt carb has issues, so now I gotta decide if I want to try and rebuild it or maybe get a Weber, though I am hesitant to go with the Weber as we have some smog controls here in Reno, NV.

camo31_10.50

i would say, if it does the same thing with BOTH carbs....start looking elsewhere besidesthe carb body...it is likely something that is not on the carb, idk what...but something lol

kinda like having a knockin noise, and thinking it's the head, then replacing the head, and you still have the noise, then going about trying to figure out why both heads make the same noise, when it's really a wrist pin or a bearing.....get what i'm getting at? lol

SwampThing

Kind of mileage are you getting? Sure you adjusted the floats properly? Hooked up a fuel/air meter to it to tell how rich you're running? Hows the timing? Checked the fuel pressure? Have you done a compression test? Cat's not clogged is it? These are all just ideas to jump start the thought process. Though I'd definitely do a compression test for giggles. Plus you'll be able to look at your plugs while you're doing it.

Smelling gas can also be something as simple as some of the body seals not being closed all the way, or by having the back window open on a 4runner.

RobW82400

Mileage, not good, I estimate 16-18 mpg.

Thanks for the new ideas everyone, seems like there are so many things that good be causing my issue. It's kind of frustrating, cause I have taken it to a couple local shops and they weren't able to figure it out, so now I end up doing it myself. Truck just went over 100K miles, so seems a shame to give up on it.

Once it's warm you rarely smell the gas, and I imagine I mostly smell it through the back window (2 seater truck) as it doesn't seal well.

I see the gas around the rim of the top opening when I take the air cover off and also see some on the lower part of the carb, maybe it's running out the top and down the sides.

I will start to look into the new suggestions and see where it takes me. If I am going to check the floats though, I may as well rebuild it again. Hate those rivets on the choke!

Thanks!

Rob W

Edit: also replaced cap, rotor, plugs and wires recently, plugs were all black from running rich.

swampfox

have checked the carb vent/carbon canister ? it might be plugged or not working properly and causeing pressure to build up. the vent solenoid may not be getting power which could explain why it happened on both carbs.

RobW82400

Nope, haven't checked the carbon canisters, I read that all they do regarding the carb is vent the gas tank at:
http://www.bluebassdesign.com/boonin/carb_faq/#cc

But, it will be the first thing I check, as there is a whoosh sound when I remove the gas cap, so who knows where else I might have some pressure?

swampfox

the vent line to the tank might also be damaged or plugged.

RobW82400

Hey all, just wanted to let anyone interested know that after checking a few of the things you mentioned to no avail I replaced the HAC valve (High Altitude Compensation) and that did the trick. I am at 4500 feet above sea level, so no doubt many of you wouldn't have this issue, heh. I no longer smell or see extra gas and am getting about 33% better mileage.

Thanks for all the help, the other things I did didn't fix the problem, but at least I wont have to mess with those things for a while, and I didn't have to rebuild the carb!

swampfox

i am glad you got it fixed.