Won't start at 15% grade under 1/4 tank

SoCal_Jeep

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Anyone ever have issues with starting your JLU when at 1/4 tank of gas and 15% downhill grade?

Backed up to watch fireworks on a hill. Gas was just over 1/4 as we were coming off the trail. Watched the show, when it came time to leave, the jeep sputtered and wouldn't stay running.

Had to pull the transmission into neutral, Got the guys to push us down the hill until we were flat enough to start. Then it ran perfect.

A quick Google search said they were working on a TSB last year, but that's all I found. Any info would be appreciated. If no TSB, is there a fix I can do?

 
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Chuckster

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I park on a steep grade in our driveway and always have a low gas alert when under a half tank, but it always starts with no problem, even when below an 1/8. 2021 JLU.
 
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mwilk012

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I park on a steep grade in our driveway and always have a low gas alert when under a half tank, but it always starts with no problem, even when below an 1/8. 2021 JLU.
you are facing up slope, yeah? OP appears to have been facing downhill, thus allowing fuel to flow away from the pump. No bueno
 


Chuckster

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you are facing up slope, yeah? OP appears to have been facing downhill, thus allowing fuel to flow away from the pump. No bueno
Nope, I usually back in so nose is pointed downhill.
 

jessedacri

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Anyone ever have issues with starting your JLU when at 1/4 tank of gas and 15% downhill grade?

Backed up to watch fireworks on a hill. Gas was just over 1/4 as we were coming off the trail. Watched the show, when it came time to leave, the jeep sputtered and wouldn't stay running.

Had to pull the transmission into neutral, Got the guys to push us down the hill until we were flat enough to start. Then it ran perfect.

A quick Google search said they were working on a TSB last year, but that's all I found. Any info would be appreciated. If no TSB, is there a fix I can do?
I can't say I have actually had it not start, but I once parked with 1/4 tank for a photo on Rowher trail in Santa Clarita facing downhill. After the photo I ended up opening up the tailgate to grab a snack, a water from the cooler, and looked out at the view for a couple minutes. When I got back in, the fuel level read completely empty and "Range Low" was displayed but I managed to make it the handful of miles back to pavement without issue. Once I was on level ground the fuel level started coming back, but it stayed that way for about 30-40 minutes while driving off the trail and I was unsure if I had a slow leak or if something was busted.


I try not to ever be caught in trail conditions with low fuel regardless - the only fix is topping off more often. I now also carry 4 extra gallons on a TrailRax mount that's filled on the weekends or holidays or otherwise whenever I think I might end up out there wheeling. Saved me on the way to Vegas for work a few weeks ago, and it looks cool.
6BAD6C82-D71D-48AD-B756-6BBFE6849DF2_1_105_c.jpeg
 

Left Field

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A quick Google search said they were working on a TSB last year, but that's all I found. Any info would be appreciated. If no TSB, is there a fix I can do?
I've not laid hands on the fuel pump assembly for a JL, but did on my last Jeep. The pump assembly was designed to run with minimal fuel in the tank and to allow operation on a slope for at least a limited time. It was clever, solved low fuel start/run issues and addressed the concern over operating the pump with low fuel levels (loss of pump cooling).

This was accomplished by having a two stage pump, with the pump located within a round vertical reservoir. Each stage had its own fuel filter. The first pump stage was high volume / low pressure and scavenged fuel, even if it was so low it was just sloshing by. This fuel was collected into the reservoir. The reservoir had an open top, so the excess fuel gathered just ran overboard back into the tank.

The second fuel pump stage was the high pressure stage and pumped fuel from the reservoir. The reservoir if I remember right held maybe a pint or two. Enough to run for a while on an incline with low fuel. This approach also kept the fuel pump submerged in all but the most extreme low fuel conditions.

Hopefully the JL pump is similar, at least in concept. What comes to mind in your case is something that is interfering with filling the reservoir (a first stage pump or filter issue), or perhaps more likely, a reservoir seal issue that is allowing the accumulated fuel to leak back to the tank. Maybe the reason for a TSB?

LF

 

Winjet
 
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