Upon running tests, I discovered that my fuel pump must be working fine. My jeep wont start unless I use starter fluid, so I figured it was my pump. But when I give her gas after she starts, she revs right up. If I keep her above 2k RPM she stays running. If I drop her at all, she dies and wont start back up without the fluid. So if she is throttle-responsive, the fuel pump works? I literally have no idea what could be wrong, but I need to get this done today so I need some input!
thanks

1995 XJ, 220k, 4.0

 

Test for good spark and actual fuel pressure.

 

How do I test for fuel pressure? I know how to use a gauge, I just dont have one and I think they are like $50, so is there another way? Also, how do I test for good spark? Im not past giving this thing a tune up where it sits, I just want to make sure im sourcing my limited funds into the area of need.

Also, could low fuel anything to do with low fuel pressure? It has about 3 gallons in it.

 

You can rent one from autozone. There is not a easier way how to test pump pressure. And what your looking for a around 35psi I think and 40psi when you pull a vac hose off. It also possible that your regulator it NFG which would explain a hard start, or that the check valve on the pump is gone, so when you turn off you loose all pressure and its not enought fuel presure in the rail to kick over and stay running.

As for testing for spark, a inline spark tester or even a screwdriver and a good ground source will tell you if you have a good spark you just need help in doin either one.

 

Tested for spark. The plug looked in pretty bad shape, and the spark was orange. Plugs, wires, cap, and rotor? Hope it works!

 

What's the name of the part that fails when there is no fuel drain back?

 

Spark should be blueish.... Still check for fuel pressure.... You can get one from harbor freight for like 20 bucks... It should be 39psi .... Also check your grounds... Make sure they are all clean... If you prime the pump will it turn on that means turn your key a few times with out starting then start it

 

Orange spark?

Tune up, recheck spark. If still orange, maybe bad coil?

 

X2 on that 1

 

Agree that a tuneup is probably in order (you should have a blue spark) but your original symptom of having to use starter fluid to start the engine sounds like a FUEL problem.

1. You need approximately 31 psi of pressure to start the engine. Rent a gauge and find out.

2. With engine running running, you should have 31 psi. Then disconnect the vacuum line leading to the fuel pressure regulator (be sure that line is pulling good vacuum and is not wet with fuel) and the pressure should jump to approximately 39 psi.

3. The fuel filter (below drivers door area along the frame rail) should be changed if it's been a while. A clogged filter can restrict how much fuel gets through. They are inexpensive; do it.

4. If fuel filter is good/fresh and you are not within fuel pressure specs as noted above, your fuel pump is "weak" and should be replaced.

 

Any updates?

 

Hey guys. Sorry it took me so long. I got the fuel pump out last night. I found a used one at a JY for $50, but the wires were cut. So after a little finagling I got the "new" pump in and she fired right up. I took her around the block and she stalled twice at high RPMs while driving, but hit 4k easily while parked without stalling. Then on my way home from bowling I kept it under 2k RPMs, but when I turned onto my street, going no more than 20 she stalled again. My spark test was orange, and I bought new plugs, but I'm yet to put them in as I am to wait until I have the dough to do the wires and cap and rotor also. Hopefully that fixes it.

 

well like everyone said above you, try replacing the coil.

You want a blueish spark

 

Bimmer valve.

 

Don't forget to pick up a bottle of spark dye. It comes in blue, red, and purple. I use blue, but feather is some red on the edges of the spark.