1. Registration trouble? Please use the "Contact Us" link at the bottom right corner of the page and your issue will be resolved.
    Dismiss Notice

Vapor Lock Issue

Discussion in 'Intermediate CJ-5/6/7/8' started by mrtii, Aug 7, 2019.

  1. Aug 7, 2019

    mrtii 1972 cj51986 cj7 2019 Sponsor

    gilroy, California
    Oct 3, 2016
    I have a 86 cj7 which has original 4.2 liter engine with a Mopar fuel injection system installed. I have noticed on very hot days under heavy load that the fuel vapor locks. Given the return line runs by the cat converter, I am wondering what if any ideas or solutions with a similar set up have done to rectify the problem. I have moved the fuel pick up from original location due to a Bulletin from mopar many yrs ago about rerouting the fuel to the rail to run under the radiator and not over the top of the valve cover. I have considered moving the fuel return line to the passengers frame rail side as a last resort. Any suggestions or comments welcome
  2. Aug 7, 2019

    rejeep Well-Known Member 2020 Sponsor 2019 Sponsor

    Rochester, NY
    Nov 5, 2009
    if you have the Mopar MPI kit I doubt its vapor lock..
    those kits run 45-50 psi

    try taking heater hose and insulating your fuel lines with it.. see if it helps.

    an in tank pump works wonders also.. did that on my injected 88 YJ 258..
    Lockman likes this.
  3. Aug 20, 2019

    nwedgar Now with TBI!

    Newnan, Georgia
    Oct 26, 2005
    I used the reflective heat barrier tubing that goes over fuel lines and it seems to help my issue. Not the same FI system, but I know it was vapor lock related since mine is a TBI off a Chevy so has low PSI to begin with.
  4. Aug 25, 2019

    Lockman My " Rosie" 2020 Sponsor 2019 Sponsor

    White City, NY 14617
    Dec 4, 2018
    I agree with rejeep .... It's most likely not vapor lock. Make sure that you have a hi volume , in tank fuel pump for FP of 30 or higher.

Share This Page

New Posts