Fuel return and vent line testing - JeepForum.com
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep CJ Forum > Fuel return and vent line testing

FREE, FREE, FREE EVENT!! Save big on Lockers now till ApriJKS Jspec Suspension BLOW-OUT FEBRUARY ONLY!! HURRY UP!Income tax season is upon us. We got what u need

Unread 07-18-2010, 09:06 AM   #1
Registered User
1980 CJ7 
Join Date: Jul 2009
Location: NC
Posts: 256
Fuel return and vent line testing

I know I have seen this somewhere on here, but I can't find it. Right now I have an MC2100 installed and I have a rich mixture I'm trying to solve. I have installed #46 jets and now the carb floods, to the extent that the bowl overflows. This didn't happen with #48 jets, only that the engine ran so rich that I am experiencing some washing of the cylinder walls. Now to the question. My fuel return line builds slight pressure when you blow into it. I doesn't when the gas cap is off. How does the vent line back to the charcoal canister work in conjunction with the fuel return line? Should both lines "breathe" freely? I have recently replaced the power valve. Thanks.

EngChase is offline   Reply With Quote Quick reply to this message
Unread 07-18-2010, 10:30 AM   #2
Registered User
1980 CJ5 
Join Date: Mar 2010
Location: moses lake WA
Posts: 130
check your rear drivers side fender and inspect the rollover check valve and the vapor vent can that sits there. sounds like something is plugged
1980 CJ-5, Ford 351w, in restoration, kind of
jeffyjensen is offline   Reply With Quote Quick reply to this message
Unread 07-18-2010, 12:52 PM   #3
Registered User
1981 CJ8 
Join Date: Apr 2010
Location: The Little Apple, KS
Posts: 3,410
let me help you with that:

Went through the same problem. Sounds like jeffy is right - there may be an obstruction between the tank, the check valves, and the canister. My valve-canister line was plugged with charcoal when I tore down the system. That link will give you a pretty solid idea of how the whole fuel emissions/canister system is supposed to work.
walkerhoundvm is offline   Reply With Quote Quick reply to this message

carb , cylinder walls , fuel system , gas cap , gasoline , jets , mc2100 , running rich , vent

Quick Reply

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Thread Tools

Suggested Threads

Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.