Engine stumbles below 1/2 tank. - JeepForum.com
 
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post #1 of 5 Old 11-20-2019, 11:43 PM Thread Starter
elchunkogrande
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1990 YJ Wrangler 
 
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Engine stumbles below 1/2 tank.

When I redid the fuel pump and filter on my YJ for the TBI install, I put it about mid frame rail for height about even with back end of the skid plate. Means that it has to suck when the fuel gets below half full. I ran some errands in it this morning and it got to stumbling. Engine would quit for a second or two before jumping forward so I filled it up and the problem went away. Guess I'll have to lower the fuel pump.

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post #2 of 5 Old 11-21-2019, 12:13 AM
Chrisnvegas
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I'll take a picture of where I mounted it tomorrow.
I think the best pump for the TBI is the Walbro. Went through a couple before getting the Walbro. It's quiet too.
Been on about 4 or 5 years now without a hiccup even in 117* heat.

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post #3 of 5 Old 11-22-2019, 11:43 AM
jhrebs
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Quote:
Originally Posted by elchunkogrande View Post
When I redid the fuel pump and filter on my YJ for the TBI install, I put it about mid frame rail for height about even with back end of the skid plate. Means that it has to suck when the fuel gets below half full. I ran some errands in it this morning and it got to stumbling. Engine would quit for a second or two before jumping forward so I filled it up and the problem went away. Guess I'll have to lower the fuel pump.


Dumb question. How do you know itís below half? Are you going by your fuel gauge? I once tore about my entire electrical system, computer and all because I was chasing a TBI issue. Turns out I was out of fuel. I just assumed my gauge was accurate.


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post #4 of 5 Old 11-22-2019, 10:15 PM Thread Starter
elchunkogrande
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You're right but I filled it up when the gauge said 1/2 and it held 10 gallons so the gauge is pretty accurate.
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post #5 of 5 Old 11-24-2019, 04:21 PM
Boojo35
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Your fuel pump has to suck regardless of the level of fuel in the tank.

A couple of thoughts.

Some YJ tanks have a baffle around the pick up which helps to control fuel sloshing and starvation during corners etc. and some do not.

You may have an air leak in your fuel tank pick up unit that is exposed below a half tank. It may not have showed up if previously carbureted as I assume it was because the fuel bowl in the carb has a reserve of fuel. An injection system however will drop pressure if starved.

If you cannot fix it with a hammer then it has to be an electrical problem.
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