OKAY SO I just finished my drive finally, it did end up doing it again but this time I think I have the problem
New fuel pump was installed this morning before I left. I bought a fuel filter to also change out just in case but didn’t do it at the time. I survived most of the day but once the tank dropped to about half full and the temperature rose above 90 degrees, it did it again
I swapped out the fuel filter on the side of the road, and the old filter was very empty inside (and rattling)
So I think my problem is this:
This Jeep was an MPI fuel injection swap. I installed an inline pump and filter on the frame, but decided to put the filter BEFORE the pump so that the pump would last longer. The problem with that is during hotter weather I think the filter is restricting the flow just enough to vapor lock the whole fuel filter, which then makes the pump have no fuel flow, which drops the fuel rail pressure to 0.
After it died again, with the new filter on, I tapped on it and the filter sounded hollow inside. I then ran the pump manually and after about 30 seconds the pressure went back to normal and it started again.
So in total, my problems have been:
when it died, I could hear the fuel rail boiling. This was because the fuel pressure regulator had a broken o-ring which would prevent the rail from holding pressure when the pump wasn’t running
After installing the fuel pressure gauge, I could see the rail pressure would drop to 0 which means the pump wasn’t pumping correctly, so I grabbed it with my hand while trying to start but could feel it running still so I thought that wasn’t it.
At this point, I think my original pump might have been good as is, and I just need to re route my fuel filter to go after the pump instead of before it
What type of fuel filter are you running? Even with the pressure regulater working the pump still have to move alot of fuel since the return is on the rail. Sounds like your filter may be causeing a restriction well obviously it does so I should say to much of a restriction for the pump to over come and it loses prime. I would at a minimum put the filter after the pump. You may want to looks at an MPFI intank set up. There is a reason the factory went to that set up. I would think one being it would be very hard for the pump to lose prime. I have a 15 gallon sender assembly still I think. I am happy to check. It would need a fuel pump though as its got a cheap chinese one in it and I definitly dont suggest them as my last 3 have lasted about a month each.