Air in fuel issue.

[DChristie]

Good morning everybunny!
Several months ago I installed The JK megafilter and lift pump. I had a few minor issues immediately after the install with no starts after driving several hundred miles
The reason-
The bleeder screw on the megafilter wasn't tightened enough, and was sucking air. I didn't want to over-tighten it an ended up under tightening it two or three times til I took a deep breath and cinched it down a little more than I was comfortable with. From then on no issues.

Fast forward to July- I pulled my 10kpound 5th wheel from South Texas to Wyoming and back. On the return trip, I stopped in an RV park for the night, next morning the truck started and died after 20 seconds. I primed the filter and cranked it back up. No problems until the next day after some more hard pulling again a start and die. I primed the filter and ran all day no problem.

My question: Even with a lift pump, could I create enough vacuum to "boil" air out of my fuel with 100 degree days and hard pulls up Texas hill country hills?

If this scenario is possible, how do I fix it? additional pump?

[Kennedy]

I would suggest that you verify the operation of the lift pump. While they are very reliable, they are not infallible. I see guys installing and not purging the air properly and this can lead to early failure.

The bleeder does NOT need to be exceptionally tight just snug. Same with the OE filter head bleeder.

[DmaxMaverick]

Check the condition of the fuel filler cap (or just replace it, they're cheap). If it isn't venting properly, it can cause excessive vacuum in the tank, especially after a warming cycle (ECT and/or climate), and will exploit any leak in the system, even those not evident of an external fuel leak.

Check the condition of the OEM filter assy bleed screw and O-ring.

Check the seals at the OEM fuel filter. The large seal at the top, WIF sensor seal, and the water drain seal can all leak air, while not allowing an external fuel leak under pressure.

If you have any indication of an external fuel leak, however slight, will allow an air intrusion leak once the pressure (provided by the lift pump) is gone.

As John said, check fuel lift pump operation, as it is critical to the integrity of the system once installed. Generally, in almost every condition, a properly operating fuel lift pump will eliminate fuel outgassing, and prevent the need of priming the system for a start, once the system has been initially bled. However, the new components, pump or filter, can be a source of leaks if not installed correctly, or if defective seals may be suspect.

How did you install the lift pump, electrically? Did you use JK's controller, installed as recommended, or wire it another way?

[DChristie]

Thanks John,

I will check the lift pump for operation.
I can't quantify how "snug" I got the bleeder screw, I have the great fortune of easily breaking 1/4-20 bolts and 1/2" jacobs chucks on drill presses by hand if I'm not very careful.
I really think I was too gentle with it initially because it was brass and I didn't want to strip it.

DMaxMaveric,

I wired it in per Johns supplied harness and instructions. I will check the fuel cap.
I recently had to replace my radiator cap because it was gummed up and causing the upper hose to collapse. (I'm the second owner and I'm discovering the previous owner didn't do much maintenance)

I have not messed much with the OEM bleeder and not at all with the O-ring, I will look at them too.

Thanks for the replies gentlemen!

Will report back soon...