Fuel pump not working (tried new one)

[Michaelmcgo]

I have a 2002 Liberty Sport (3.7L) that's been extremely reliable until now. My wife was driving and it just shut off. It will turn over fine, but never even catches. Here's what I tried:

-Starting with gas pedal to the floor.
-Got some studdering with starting fluid in the air intake.
-Replaced all fuel related fuses and relays with known working ones.
-Replaced fuel pump and filter, thinking it was a bad pump at this point. Still no gas. I tried starting with the gas out line disconnected but the pump wasn't running.

So I think I have a deeper problem. Possibly computer or wiring related.

Any ideas?

 

[tjkj2002]

Checked the ASD relay?

Never use starting fluid in a gas engine,can and will destroy the rings.

 

[Michaelmcgo]

Well shoot, my Dad taught me to use it to diagnose, guess I'll pull that trick out if the toolbox.

Would the crankshaft position sensor prevent the fuel pump coming on even when the key is first turned?

I have an auto-start installed, are these easy to bypass?

 

[Billwill]

Well shoot, my Dad taught me to use it to diagnose, guess I'll pull that trick out if the toolbox.

Would the crankshaft position sensor prevent the fuel pump coming on even when the key is first turned?

I have an auto-start installed, are these easy to bypass?

Put a voltmeter on the Black/White wire at the pump. You should be getting +12 volts there.
Black wire goes straight to ground.

Check fuse 24 in the PDC under the hood and the fuel relay is there as well.
Check fuse 15 in the Junction Block inside the cabin.

Swap the fuel relay with a similar one and you can pull the relay out and jumper pins 30 and 87 in the socket....that should supply +12 volts direct to the pump.

 

[Jax2A]

I'm chasing the same demon on my 2002 sport...

Does your gas gauge work? Mine isn't. My front wipers won't turn on either. And my OBDII port isn't communicating. My next step was going to be to drop the tank and start checking the fuel pump/gauge voltage and grounds before changing the fuel pump. Already checked the fuses & relays. Also just changed the crank position sensor (which was a mother!) and the camshaft position sensor today with no love.

Does anyone know if the fuel gauge will still work when the fuel pump dies?

This one is driving me crazy!!

 

[Michaelmcgo]

@Jax2A:
It sounds like we are chasing the exact same problem! Try this: jumper your fuel pump relay and see if the fuel pump turns on. I did this (after already replacing my fuel pump because I thought it was bad).

I think with no spark, no command to turn the fuel pump on, no codes, and a funky dash the ECM has gone bad. I'm ordering a working one off eBay right now. Do I have to have it reprogrammed or can I just slap one if i it's the exact same PN as mine?

This is what my dashboard looks like with the key in the "on" position. I think all the dummy lights are supposed to go away after a few seconds. Note the fuel gauge and RPM meters (I have 3/4 a tank of gas and the engine is obviously not running):

You must be registered for see images

 

[tjkj2002]

Do I have to have it reprogrammed or can I just slap one if i it's the exact same PN as mine?

Yes itv will need to be programmed.

 

[Michaelmcgo]

Yes

My Jeep is stuck on a dirt road 50 miles from the nearest Chrysler dealership. Is this something a mechanic can do?

Does it have to do with the RFID keys? Could I buy a brand new sentry key and just reprogram it on the spot?

If I did replace the computer and not program it, could I limp it back to town? I'd like to be able to know after replacing the computer that it fixed the problem. I would be able to stomach a 50 mile tow charge a lot better...

 

[tjkj2002]

My Jeep is stuck on a dirt road 50 miles from the nearest Chrysler dealership. Is this something a mechanic can do?

Does it have to do with the RFID keys? Could I buy a brand new sentry key and just reprogram it on the spot?

If I did replace the computer and not program it, could I limp it back to town? I'd like to be able to know after replacing the computer that it fixed the problem. I would be able to stomach a 50 mile tow charge a lot better...

You'd need the DRBIII(or Starscan if '05+),a fast internet connection,and authrized access to Chryslers website to download the programs.Chances are the Jeep would not even start if your running can bus system.

 

[Billwill]

@Jax2A:
It sounds like we are chasing the exact same problem! Try this: jumper your fuel pump relay and see if the fuel pump turns on. I did this (after already replacing my fuel pump because I thought it was bad).

I think with no spark, no command to turn the fuel pump on, no codes, and a funky dash the ECM has gone bad. I'm ordering a working one off eBay right now. Do I have to have it reprogrammed or can I just slap one if i it's the exact same PN as mine?

This is what my dashboard looks like with the key in the "on" position. I think all the dummy lights are supposed to go away after a few seconds. Note the fuel gauge and RPM meters (I have 3/4 a tank of gas and the engine is obviously not running):

You must be registered for see images

That light that shows a Key with a line through it is the SKIS system saying that it is not happy with the chip that is in your key.

What you can try to do is turn on the ignition, pull out the ASD relay, jumper the normally open contact points same as you did for the fuel relay and try start the engine

If that Key symbol is flashing it means the SKIM module did not send the correct code to the ECM but if the Key light is ON solid it means the ASD relay did not send an acknowledgement signal back to the ECM that it, the ASD relay, has energised.

And you will definitely need to get your new ECM (PCM actually in a gasser) programmed at a dealer as stated.:freak3:

 

[Jax2A]

I don't have the key w/ line through it light on mine, but my check engine light on the right is on. Are all 2002 Jeep keys chipped? I'm pretty sure I had a spare key made at Home Depot and it worked. I'll have to dig it out a recheck it.

I'll jumper my fuel pump though to check it before I go dropping the tank... that's a good tip that may save me a ton of work. Guess I'll start looking at ECM's too...

Does the ECM have to be installed in the Jeep to be programed? My Jeep is also sitting a long ways from any dealer at my Dad's barn.

 

[tjkj2002]

Does the ECM have to be installed in the Jeep to be programed? My Jeep is also sitting a long ways from any dealer at my Dad's barn.

Yes.

 

[Jax2A]

Yes.

If I buy a used one from the exact same Jeep model, would it need programmed? Wouldn't the flash memory stay preserved?

Also, we're talking about the module behind the battery, correct?

Last night I jumpered my fuel pump relay and forced it on, so it's good. I also swapped the ASD relay with the blower relay (blower still works) and confirmed that's good.

Before I buy a ECM, how do I confirm that is the problem and that there isn't another problem that fried the ECM? I read a "NAPA tip" that said they rarely fail on their own.

 

[Billwill]

If I buy a used one from the exact same Jeep model, would it need programmed? Wouldn't the flash memory stay preserved?

Also, we're talking about the module behind the battery, correct?

Last night I jumpered my fuel pump relay and forced it on, so it's good. I also swapped the ASD relay with the blower relay (blower still works) and confirmed that's good.

Before I buy a ECM, how do I confirm that is the problem and that there isn't another problem that fried the ECM? I read a "NAPA tip" that said they rarely fail on their own.

You can try jumping out the ASD relay normally-open points.
Maybe the crankshaft position sensor or the cam position sensor are faulty?:shrug:

Edit to add: I see on the other site that you have replaced those two sensors.

 

[Jax2A]

You can try jumping out the ASD relay normally-open points.
Maybe the crankshaft position sensor or the cam position sensor are faulty?:shrug:

Edit to add: I see on the other site that you have replaced those two sensors.

If I jumper out the ASD relay, what should I check/expect?

 

[Billwill]

If I jumper out the ASD relay, what should I check/expect?

It may allow the fuel pump to run and you may get a spark.
It may even start but then you had better shutdown straight away as the PCM may be trying to tell you that there is a major problem and that is why it is disabling the ASD relay.:freak3:

 

[tjkj2002]

Have you ever thought that the ignition switch maybe bad?

While PCM's do fail it is pretty rare.

 

[Jax2A]

Have you ever thought that the ignition switch maybe bad?

While PCM's do fail it is pretty rare.

No, I hadn't considered the ignition switch since it does crank. Could the ignition switch have something that could go bad and affect all the other stuff?

 

[Jax2A]

Hey Michaelmcgo,

You make any progress with your Jeep yet?

 

[Jax2A]

Well, I may have found my problem, or at least the root cause of it. Last night I went to remove the PCM and noticed some leaves and grass deep in engine compartment down where the inner fender meets the fire wall. Apparently a mouse must have took up living space in my engine bay and chewed up the wire harness between the PCM and the body control module inside. Damage is right where it goes into the firewall. I tore apart the interior (kick panel and under dash stuff) and was able to pull enough harness back inside that I should be able to repair it. I found at least four wires completely severed and several others gnawed upon but it was getting too dark to see by that time.

Hopefully the wire damage is all I have to repair. Feels good to at least have a known problem to attack.