4.0L problem

lobsterdmb · Sep 15, 2004

Ok, last friday my gas tank got really low and the jeep sputtered a little. I filled it up and ever since then it misfires after driving for a few minutes and then sometimes the RPM goes to zero and it seems to get no fuel. As soon as I hit the gas it jumps up as long as I do it right away. If not it cuts out. I just replaced the fuel filter and it didn't seem to help. This is a 1996 4.0L HO w/ auto and NP231.

John

Rev Den · Sep 15, 2004

lobsterdmb said:
Ok, last friday my gas tank got really low and the jeep sputtered a little. I filled it up and ever since then it misfires after driving for a few minutes and then sometimes the RPM goes to zero and it seems to get no fuel. As soon as I hit the gas it jumps up as long as I do it right away. If not it cuts out. I just replaced the fuel filter and it didn't seem to help. This is a 1996 4.0L HO w/ auto and NP231.

John

Check your fuel pressure. If it is dropping out you may have damaged the pump, or plugged the screen in the tank.

Rev

lobsterdmb · Sep 15, 2004

it only drops intermittently, and it seems to do it more often when turning while moving slow....

Matthew Currie · Sep 16, 2004

Funny thing, mine has been doing that too, and got really nasty this morning, stalling on hard left turns. I checked everything, and couldn't find a problem, so I'm guessing it's water or crud in the tank. It got better after a while. I threw in a couple of bottles of drygas anyway, and am waiting to see if it helps.

lawdog · Sep 18, 2004

If you ran the tank low enough to sputter you may have air in the fuel rail. There should be a schrader valve on the rail itself. There is probably a better way to do this but I have always turned the ignition to on( so the pump will run) take the cap off the valve and as you cover it with a rag press the valve with a small screw driver. Air should sputter out. It may take a couple times but that should solve the problem.
Make sure you use a rag or gas will go everywhere.
Good luck.

Professor Bobo · Sep 18, 2004

You can try bleeding the fuel rail, but It sounds like you got crud in your tank and it's prob plugging up your sock. (The cloth filter on the pump pickup.)
Gas floats on water (like oil).
Pulling the pump assembly isn't too bad on an XJ, atleast you don't have to pull the tank. Unless you're going to clean out the tank...I would recommend that.
But check the easy and obvious first.
Good luck to you, and be extra careful around gasoline.

Dr. Dyno · Sep 18, 2004

lawdog said:
If you ran the tank low enough to sputter you may have air in the fuel rail. There should be a schrader valve on the rail itself. There is probably a better way to do this but I have always turned the ignition to on (so the pump will run) take the cap off the valve and as you cover it with a rag press the valve with a small screw driver. Air should sputter out. It may take a couple times but that should solve the problem.
Make sure you use a rag or gas will go everywhere.
Good luck.

If you've got enough gas in the tank, there shouldn't be any air in the fuel rail.
The most likely problem is either that the fuel pump sock has become clogged up with crud or that the fuel pump itself was damaged. The pump needs fuel to keep it cool and if you run the tank too low, you risk frying the pump. That may be what's happened here.

4.0L problem

lobsterdmb

Just a Lobster Minion

Rev Den

NAXJA Forum User

lobsterdmb

Just a Lobster Minion

Matthew Currie

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lawdog

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Professor Bobo

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Dr. Dyno

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