I've been driving the Montero diesel on and off for short trips but have been dealing with a problem after short highway drives. When I park it after 10-15 minutes of highway speed driving, when I go to crank it I'm having trouble getting power. Eventually, it dies out and I have to get it towed home. I was leaning toward a clogged fuel line or problem with the lift pump but they check out ok.
The other day, I noticed that the fuel cap on the truck was still from the gas engine and was marked, "Vacuum Only." My theory is that after driving on the highway, there was vacuum building up in the tank since the vent line no longer goes to the charcoal canister... it is now my fuel return line. Therefore, when the pump tries to get fuel, the vacuum in the tank was starving it for fuel.
I bought a Stant 10830D green diesel cap at Advance Auto on the way home and installed it. I plan on driving it this weekend on the highway and then going straight home to park it. (avoid towing) Hopefully, this will solve the issue. I have a better 3-5psi lift pump to install in place of my cheap Mr. Gasket diesel transfer pump. My engine needs a lift pump. I have it on a fuse and when I pull the fuse, the engine loses power and konks out.