carb problems on 85 22R

[whitesell7]

My 85 truck is gaining volume in the oil pan and it smells like gasoline. Normally I use a quart of oil every 2000 miles or so, but now I am gaining. My carb shows a normal fuel level when I park it. However when I come back a couple hours later the gas does not show in the fuel level window. What is leaking in the carb?

I am familiar with a similar on old Quadrajets where the fuel well plugs would leak and have to be repaired and a similar problem with old Holley power valves. Does this Aisin carb have a similar setup? Any help would be appreciated before I tear into the carb. I just want to know where to look for problems.

Thanks for any advice.
whitesell7

[Rycam]

The main problem is with the Aisin carb is the AAP diaprhram. A leaky one can cause fuel washdown, and the extra gasoline can remove enough oil from the piston walls to increase cylinder wear dramatically. The AAP can be accessed on the outside of the carb. The AAP (AUXILLARY accelerator pump) in proprer running engines is only used when the engine is cold.

Seeing that the volume of fuel in the crankcase is enough to be seen on the dipstick, you want to look at a bad mechanical fuel pump. A leaky diaqphram here can definitely allow enough gasoline to drain into the head, and down to the crankcase.

Fuel plugs like the Q-jet, may be present on the Aisin, but after reading thousands of posts, this has never been a problem. I have yet to rebuild the carb on my 1984 22r 4x4.

[Rycam]

The site below is among the best to ask your question. Not to kick mud on this board...but gasoline makes a crummy lubricant, and you need help fast. Sign up, and ask your question there (cut and paste!)

http://www.4x4wire.com/forums/postli...t=&Board=UBB11

Also, feel free to use the SEARCH function as the AAP diaphragm and "gasoline in the crankcase" issues are not un-heard of.

[whitesell7]

Thanks for the link! I found some useful information there. I did read one post that said "you don't ever want to adjust that screw. May as well get a differant carb" refering to the idle mixture adjustment screw that is sealed. Is there something secret or special about that screw? My engine has always run rich and I was looking forward to taking the seal off and setting the mixture where I wanted it. Any ideas?

Thanks
Robert

[Rycam]

If there is any secret, it is that the factory knows what they are doing. If it is rich, the try other things like insisting on Toyota Parts for the filters and ignition. Also, see if the both the distributor's vacuum advance diaphrams are holding vacuum.

[reb]

The factory shop manual says not to tinker with it. I get the impression that the concern is emissions. I have tinkered with sealed idle adjustment screws on other vehicles without causing operational problems. I would think that if you have to get into the carburetor and do much inside, adjustment of the idle screw could well be necessary. I would probably make sure everything else was correct before adjusting it otherwise, though.

reb

[Mike Stroup]

Nothing sacred about that little screw according to the factory service manual for my '90 22R. As I recall all that's needed is the correct size drill bit to help remove the old plug, and a tachometer and screw driver to properly readjust the little critter. I recall the manual prescribes installing a new plug after the readjustment, but I never did.