Motor dying on steep incline help

BigClay

BigClay

Knower of useless ZJ things
Joined
Sep 24, 2008
Location
Winston-Salem
Last weekend out on the trail the jeep did very well until I got to steep hill climbs. I would have great throttle response until I got at the angle, then in four wheel high, first (or second gear) pedal to the floor (and hand throttle on just incase a few times) the motor would die. This is a 98 4.0 jeep motor. Any thoughts? Fuel pump? Fuel regulator?
 
BigClay said:
Last weekend out on the trail the jeep did very well until I got to steep hill climbs. I would have great throttle response until I got at the angle, then in four wheel high, first (or second gear) pedal to the floor (and hand throttle on just incase a few times) the motor would die. This is a 98 4.0 jeep motor. Any thoughts? Fuel pump? Fuel regulator?
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Grab a fuel pressure reading. I think spec is 35psi. Maybe try the same procedure but find a steep incline and see if it differs. Maybe fuel filter is jammed. Did you smell and fuel leaks out there?


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NickMaul said:
Grab a fuel pressure reading. I think spec is 35psi. Maybe try the same procedure but find a steep incline and see if it differs. Maybe fuel filter is jammed. Did you smell and fuel leaks out there?


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Click to expand...

Didn’t smell any fuel
 
Fabrik8 said:
How full was the tank?

Do you ever put it under the same amount of engine load without being on a incline?
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Less than half a tank. Oh yeah, had the hammer down on the road.
 
Mine is doing the same, but even on flat ground when under a load and I try to rev past 3k. I think it’s my fuel filter. It’s been very inconsistent so it’s been hard to duplicate and diagnose it. That is until last weekend coming back with Joe Jones we were able to make it do it on command. Seems to starve for enough fuel in the high RPMs. Changing the fuel filter this weekend.
 
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Filter is a great place to start. My old 98 Chevy truck started running out of gas on steep inclines, towing my CJ. Second gear, near flat on the floor, 3000 rpm. Took a while to diagnose, but my fuel pump was about to go out, & I was sucking more than it could pump!
 
Pump starving the motor. Strap a gauge on it, run it awhile. Had a few pumps deliver fine @idle and @high rpm, until it ran awhile, then it'd fall on its face. You could put an inline HP pump after the in tank one after the filter to compensate. Just power it off the same wires that feed the in tank did that to my xj though the in tank is still under warranty. Check MAP & TPS for giggles.
 
Are you sure it had enough gas in the tank? TJs will starve for fuel if they have much less than a half a tank, depending on the angle of the hill, camber, etc. Somewhere around 3/8s of a tank, you'll start seeing problems.

Since we don't know the exact circumstances, you might have needed to be in 4lo, too. Too much hill, not enough gearing.
 
Clay and Phillip, have y’all changed your fuel filiters yet?

If you need to borrow my fuel pressure gauge your welcome to it. Just let me know and I’ll bring it to Potts
 
I bought a new fuel filter, so I’m half way there! Gonna change it before Potts Mountain.
 
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Before I do a v8 swap, stroking to 4.7 will happen
 
Bumping this back up.

So replaced the fuel pump (and related internal filter).

When I was in Harlan, I made sure I had a full take of gas at all times. I did some hills just fine in 4 low, with the hammer down, then I would try to do the next hill in 4 high, and it would stall on me half way up the hill. The stalling is like I am not giving it enough pedal, but it is always to the floor. What other suggestions do you guys have?
 
BigClay said:
Bumping this back up.

So replaced the fuel pump (and related internal filter).

When I was in Harlan, I made sure I had a full take of gas at all times. I did some hills just fine in 4 low, with the hammer down, then I would try to do the next hill in 4 high, and it would stall on me half way up the hill. The stalling is like I am not giving it enough pedal, but it is always to the floor. What other suggestions do you guys have?
Click to expand...

I'd look toward the tps.
 
BigClay said:
Bumping this back up.

So replaced the fuel pump (and related internal filter).

When I was in Harlan, I made sure I had a full take of gas at all times. I did some hills just fine in 4 low, with the hammer down, then I would try to do the next hill in 4 high, and it would stall on me half way up the hill. The stalling is like I am not giving it enough pedal, but it is always to the floor. What other suggestions do you guys have?
Click to expand...

What RPM is it turning when it stalls?

It could be too much hill for 4hi. You just don't have the gearing to pull the grade.
 
What brand pump did you get?

Cheap ones can be bad right out of the box. The WJ I had had two bad ones in a year and the one in my TJ that was replaced in the last year or so is also bad.

I have a fuel pressure gauge if you want to check. Does it hesitate to crank?
 
shawn said:
What RPM is it turning when it stalls?

It could be too much hill for 4hi. You just don't have the gearing to pull the grade.
Click to expand...

It would start to stall in 4hi if I was starting to climb a rock on flat ground. Always in 1st gear
 
Desertfox1023 said:
What brand pump did you get?

Cheap ones can be bad right out of the box. The WJ I had had two bad ones in a year and the one in my TJ that was replaced in the last year or so is also bad.

I have a fuel pressure gauge if you want to check. Does it hesitate to crank?
Click to expand...

It always cranks just fine. I will check the fuel pressure again.
 
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