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Exhaust smoke and rich condition

Rick Allen

NAXJA Forum User
I have a 1993 xj 4.0 mild work mostly stock. the problem i have is after the truck has warmed up around 185/190 i get exhaust smoke during idle. i traced the problem to the evap canister, i disconected and plugged the vac line (fixed vacume leak i couldn't find ) and caped line going to air box cover. has not smoked since. what is causing the evap system to over fuel my engine. should i just delete the canister or is there another resolution i am over looking. I do wheel this truck hard. if i delete the canister where do i run the vapor line from the fuel tank.
 
First off, where is the exhaust smoke showing up, tail pipe or vacuum lines under the hood?

What makes you think it is being over fueled? What does the tail pipe exhaust look like?
 
The smoke is coming from the tailpipe, it is black and smells of very rich unburned fuel, since bypassing the evap canister i haven't seen the smoke since and i got an extra 32 miles out of this tank of fuel. I don't get it at all unless it has to do with evaporative rate of ethanol mixed fuel. I have checked and rechecked everything and it just doen't make since it would go away by disconnecting the evap canister..wtf
 
I would get an FSM chart that shows the routing for all the lines and hoses. Sounds like some lines got crisscrossed somehow to me. I am not sure how that thing is plumbed, but it sounds like it was sucking raw gas out of the tank into the canister, then into the intake.
 
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