Fuel system fault

[Darmani]

Have a problem with my Montero 2002. Saw CHECK ENGINE few weeks ago. Cleared ECU and after 4 days same thing. Did a scan and it showed VERY SMALL FUEL SYSTEM LEAK. Deleted a fault. After 4 days same thing. Decided to change gas tank cap. Deleted a fault and after 4 days same thing. Dind't feel any gas smell, engine works fine. Any oppinions?

Mitsubishi Montero 2002 3.5 V6

 

[RyanY]

Charcoal canister, filler neck, or any of the numerous fuel vapor lines could be leaking. Could also be the tank itself if you live in a rust-prone location (not sure if the Gen3s still used a metal tank or switched to plastic). Best bet would be to download the FSM, figure out which lines are your vapor lines, and start inspecting for signs of damage or cracking - the lines are the most likely source of a leak, especially the ones running under the vehicle where they're more prone to damage. If it's similar to the Gen 2s, the sending unit/fuel pump attachment point on top of the tank is another possibility - it has some sort of seal or o-ring that could be leaking.

 

[Inyo_man]

My 2002 exhibited the same issue a number of years ago.

I found a very small o-ring that had degraded over time.

Access the top of the fuel tank through the panel inside.
Clean the top of the fuel pump assembly.
(I don't recall which line had the bad o-ring- sorry)
Disconnect the lines from the fuel pump assembly; inspect the o-ring carefully and replace if needed.
HTH