1994 XJ has no fuel

1994 Sport, 4.0, AW4/231 XJ

This is my beater rig, and it has never let me down until the other day. It will turn over but never start up. I haven't had much time to diagnose it, but this is what I have done. Please point me in the right direction to get this baby going again.

It ran and drove fine, then I started it and it only ran for a couple of seconds and died. It never started back up again, but it will turn over.

I checked the fuel at the rail, no gas.
It has a full tank. I'm sure.
I checked all of the fuses, all were good.
I swapped the ASD relay and fuel pump relay with others but that didn't help.
I unplugged the crank position sensor and plugged it back in. No start.
I put a new crank position sensor. No start.
I changed out the corroded battery cables. No start.
I listened for the fuel pump to prime when I turn the key on, it does NOT prime.
It's getting ~5 volts at only one pin on the pump harness while the key is on.
I pulled the pump out and cleaned up the ground connection on it (in the tank)
I jumped the fuel pump relay, and that DOES make the pump run.

What am I missing here? Should I just put a new fuel pump relay in it? I have extras that I swapped out, and they won't make it pump, but why does the pump run if I use a jumper wire on the 30 and 87 pin? Any ideas about what to look at or test next? Thanks in advance.

Anybody???

I forgot to say that I also took the harness off of the under dash fuse panel and I inspected all of the connections and cleaned all of the gunk out of it, then put in a lot of dielectric grease but there was no change.

Also, I tried to start it with the fuel pump relay jumped, but it wouldn't start. I guess I'm not getting fire. It's kinda hard for me to check without a helper.

Also, I'm not sure if it matters but I noticed something happening. The tach flutters around when you turn the key on. It just bounced around in the 1500 rpm range. It may have do e that before or maybe not, I can't remember. Could that be a sign of a wiring issue or something?

From what you have posted I am guessing that whatever it is that is not telling the fuel pump to run is also not telling the ignition to fire.

I would start looking into the wiring to the computer, and particularly to the related ground connections for that.

Beyond that, my next effort would probably be to try another computer.

If and when you get it figured out please post back with the results.

Does your check engine light come on? Have you tried checking the stored codes using the key method? If you are getting "no check engine" light when you turn the key to the run position, it may be because you have have shorted sensor or wire. Most call it a BUS fault.

The prime not working throws me. Never seen it before. The PCM needs two electrical inputs before it will work, one is battery plus and the other is from the ignition switch, either gets interrupted and the PCM shuts down.

It may be the PCM, it happens sometimes. More often it is a sensor or wiring issue. Sensor and wiring issues are hard to troubleshoot and can take a long time, but a whole lot cheaper than a new PCM.

If you get no "check engine light" when you turn the key to the run position, try unplugging sensors one at a time and see if the CEL comes on.

Nope, no check engine light. I'll try unplugging sensors and see what happens. Thanks.

Re: 1994 XJ has no fuel or fire

I have very limited time to work on my Jeep, but here's an update.

I went over all grounds again, and I only got to unplug a few sensors but there has been no change. I plan to continue trying that.

I have been doing tons of research and decided to check out my ignition switch. There were a couple of burned connections on the switch, and one of those was burned on the plug. I had another switch from an old steering column that came out of this same Jeep so I swapped it in but there was no change. Still no fire or fuel. I'm planning on going to a pick a part to look for a computer and at least the plug for the ignition switch. I had checked all of the fuses before and they were good, I'm also planning on checking those again to see if any burned out after the "new" ignition switch.

If anybody has any other ideas, let me know. Thanks.

Also, I forgot to add that I checked the bulb for the check engine light and it was good. The check engine light still doesn't come in when you first turn the key on.

yj_evolution said:

Also, I forgot to add that I checked the bulb for the check engine light and it was good. The check engine light still doesn't come in when you first turn the key on.

Click to expand...

my 91' does the same thing. check engine light wont flash when key is turned on. dont know why it hasn't failed smog yet so not sure if its just an early year thing or not.

Check the fuel pump ballast resistor? It's the squarish-looking ceramic thing, with two
wires attached to it, on the top edge of the driver's side fender, across from the brake
master cylinder.

Some folks bypass it, but this should be done only on a temporary (emergency) basis.

Mine doesn't have anything on the driver's side fender except for the computer. Would it be in the wiring loom, or directly on the inner fender?

yj_evolution said:

Mine doesn't have anything on the driver's side fender except for the computer. Would it be in the wiring loom, or directly on the inner fender?

Click to expand...

It looks like this:

Royal Nonesuch said:

It looks like this:

Click to expand...

Nope, I don't have that on mine unless somebody moved it. That should be on a '94?

yj_evolution said:

Nope, I don't have that on mine unless somebody moved it. That should be on a '94?

Click to expand...

mine is back on the firewall behind the intake.

Maybe it was eliminated in '94? My '93 had one. My '96, and '98 XJs do not have them.

here's an idea that will help narrow down your no-start condition. Take the fuel pump out of the equation by "hot wiring" it to a known good power source. Tap into the hot side of the tail light circuit and run it to power on the pump. Now, when you turn on your tail lights, pump should run and provide fuel pressure at the engine. If it still doesn't start, then you also have spark issues.

I jumped the fuel pump relay and the pump does run. I did NOT check the pressure at the rail, but without jumping the relay the pump didn't come on at all. I tried to start it with the relay jumped but the engine didn't fire.

I used a spark tester to check it out and it does not have any fire.

If it were the crank sensor, would it only cut the fire and have no effect on the fuel? That's what I understand. I had put a cheaper parts house Crank sensor on it but nothing changed so I put the original back on. I really don't want to go get one from the dealership if it doesn't need it though. I haven't priced one from them yet but I imagine it will be pretty high, so I don't want to waste time and money if the crank sensor is not what is causing this issue.

Just to close this out, mine was the ecu. I got one online and put it in, and she started right up. Thanks everybody.

My brothers 91 has a fuel pump ballast resistor but its located up near the brake booster. I know all renix have them but not sure what year they stopped using the ballast resistor on the HO motors.