FJ60 carb fuel mix question (1 Viewer)

Joined
May 24, 2016
Messages
1,139
Location
Memphis TN
Ive got a desmogged 2f with an aisin carb, and was wondering if there was any other ways to lean out the fuel mix besides lean drop? I have done the lean drop twice with similar results each time. Exhaust smells a little rich, and i get this black water/carbon spray on cold start up that sprays onto the ground and sometimes drips out of my exhaust pipe. My research on here says that its due to rich fuel mixture.

Maybe im not doing the lean drop right? Are there any other factors that would contribute to this black spray coming out of the exhaust and smelly exhaust?


Thanks!
 

OSS

Joined
Jun 30, 2017
Messages
3,111
Location
Oblivion
Stinky exhaust often is caused by a dead catalytic converter. If the engine is tuned to perfection, the exhaust will still stink if the cat is dead.
The black drops spitting out of the tailpipe in the morning are from the dirty exhaust pipe getting cleaned by the water vapor condensation created from a cold engine and cold exhaust system. It's normal if the exhaust pipe is sooty.
 
Joined
May 24, 2016
Messages
1,139
Location
Memphis TN
Stinky exhaust often is caused by a dead catalytic converter. If the engine is tuned to perfection, the exhaust will still stink if the cat is dead.
The black drops spitting out of the tailpipe in the morning are from the dirty exhaust pipe getting cleaned by the water vapor condensation created from a cold engine and cold exhaust system. It's normal if the exhaust pipe is sooty.

So I’ve got a new header, new exhaust, new cat, and new muffler hahaha probably should have mentioned that in the post. That being said, the previous owner left like a 2 foot section or original pipe in there for some reason, but for the most part, it’s all brand new
 

2mbb

SILVER Star
Joined
Sep 1, 2003
Messages
5,077
Location
WC, CA
What was done for the desmog? If you removed the air injection pump, then the catalytic convertor won't work properly. The cat needs air (oxygen) to properly convert the exhaust gases.

Setting the idle mixture screw only adjusts the air/fuel mixture at idle. Once you start driving, other carburetor circuits come into play that are not effected by the idle mixture screw.
 
Joined
May 24, 2016
Messages
1,139
Location
Memphis TN
What was done for the desmog? If you removed the air injection pump, then the catalytic convertor won't work properly. The cat needs air (oxygen) to properly convert the exhaust gases.

Setting the idle mixture screw only adjusts the air/fuel mixture at idle. Once you start driving, other carburetor circuits come into play that are not effected by the idle mixture screw.

I’m not going to lie, the previous owner desmogged it, but rebuilt the carb. They also removed the oem cat, but I installed a new universal cat and oem stylemuffler. The new cat doesn’t have an air inlet. It also has a dui dist

the reason I thought it was fuel mix is I’ve had a few 22re motors with this same style cat and not had as much smelly exhaust. This is my first carbed vehicle though, and my first time seeing the liquid black stuff come out of the exhaust
 

FJ40Jim

The Cruiser Whisperer
SILVER Star
Joined
Sep 26, 2003
Messages
10,962
Location
Lancaster, Ohio, USA
Why do lean drop? (That's a rhetorical question)

Lean drop is an adjustment to get the right amount of stank in the exhaust to feed the cat.

A desmogged engine should be idle mix adjusted per the non-smog FSM: Adjust mix screw to achieve highest RPM or highest vacuum (same thing).
That is the point where CO and HC are lowest.
 
Joined
May 24, 2016
Messages
1,139
Location
Memphis TN
Why do lean drop? (That's a rhetorical question)

Lean drop is an adjustment to get the right amount of stank in the exhaust to feed the cat.

A desmogged engine should be idle mix adjusted per the non-smog FSM: Adjust mix screw to achieve highest RPM or highest vacuum (same thing).
That is the point where CO and HC are lowest.


I just did lean drop because thats what ive found so far with the FSM and the forums on being the only way to adjust fuel mixture on these carbs.
To be honest, my only experience with carbs thus far is like dirtbikes, lawn equipment, and old 1980s honda motorcycles.


So for this non smog idle mix, are you saying to adjust the idle mix screw until it stops increasing in Rpm, then back off the idle screw on the rear to bring it back down to 650 RPM?


Where are these non smog FSM's located haha everyting ive been able to find is for the smogged equipment
 
Joined
May 24, 2016
Messages
1,139
Location
Memphis TN
Download the FSM here:

Follow instructions on page 2-12.


Jim im also having a mysterious case of losing oil which at first i thought was coming out of my tailpipe, but it seems like that is just carbon and water. I have no leaks whatsoever around the motor. I cant really smell burning oil when driving, sometimes i can smell it when i turn the AC on. I did a 400 mile trip recently and it used almost a half gallon. Not really noticing any blue smoke at idle or at start up.


Any pointers on where to start looking?
 

Users who are viewing this thread

Top Bottom