Engine 1972 Jeep CJ5 - Fuel Smell

[Nick S]

Hi Everyone,

I have a 1972 Jeep CJ5 and it takes about 10 seconds to start with the key turned and then a plume of smoke that smells like gas comes out the tailpipe. It also smells gassy while driving. I have checked and adjusted the carburetor and inspected the air cleaner housing but am having difficulty finding the TSM for 72 that really shows how the fuel vaccum lines, canister, charcoal filter, and other components work together so I can trace it back to the source. I cannot find a visible leak anywhere. Any leads are greatly appreciated.

 

[TSB8C]

If the carb is adjusted properly, sounds like issue(s) with vapor system. Black smoke of course means you're running too rich. Some items to check:

1) You sure on the carb adjustment? You can rent/buy an O2 sensor to stick in the tailpipe and really ensure the carb is adjusted as accurately as possible. My rule of thumb if no measurement device was to adjust the mixture screw(s) in until the engine started to stumble a bit (too lean), then back the screw(s) out 1/2 turn.
2) Stuck float in the carb allowing it to flood. This could also account for hard to start issue.
3) Charcoal canister is flooded/saturated allowing liquid fuel to be sucked in to carb
4) Fuel pressure too high (fuel pump)
5) Plugged vacuum line (restricting expected normal air flow into engine). EGR valve, PCV valve, etc.
6) Other air restriction. You said you checked the air filter. What about oil breather filter?

Here's a vacuum line routing diagram for the AMC 304 :

 

[Posi]

What is your vacuum reading?

 

[flyn hawaiian]

Hi Everyone,

I have a 1972 Jeep CJ5 and it takes about 10 seconds to start with the key turned and then a plume of smoke that smells like gas comes out the tailpipe. It also smells gassy while driving. I have checked and adjusted the carburetor and inspected the air cleaner housing but am having difficulty finding the TSM for 72 that really shows how the fuel vaccum lines, canister, charcoal filter, and other components work together so I can trace it back to the source. I cannot find a visible leak anywhere. Any leads are greatly appreciated.

Sounds like a carb issue. Float adjustment, sticking needle and seat. Also vapor cannister bad. I eliminated my cannister, "y' the 2 hoses together and put on a 1 way check valve. The smell went away