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bill
bill, ASE Certified Technician
Category: Jeep
Satisfied Customers: 951
Experience:  21 yrs in the field 19 with Dodge Chrysler Jeep expert in electrical drivability
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I have a 92 jeep cherokee 4.0L with 5-speed stick. Engine

Customer Question

I have a 92 jeep cherokee 4.0L with 5-speed stick. Engine starts no problem but immediatley stalls even if I try to pump the gas. I have no vacuum leaks, recent tune-up, good fuel supply. I replaced the IAC valve but no difference. I have no security device on the vehicle and checked the flash codes for which I only recieved "55" - end of message code. This problem happened when I drove the vehicle for about 30 mins and shut it off at gas station. I started my engine and then shut it off about 10 seconds later only to have this start then die condition. It would sputter and barely run but die when I gave it some gas. Now it just starts and dies without any sputtering. I was thinking bad TPS but not sure if it makes a difference because it's a stick shift.
Submitted: 5 years ago.
Category: Jeep
Expert:  Amedee replied 5 years ago.
Hello!

What is fuel pressure?

Does it stay running with starting fluid?

When it stalls, is the check engine light on?
Customer: replied 5 years ago.
Hey there!

Not sure about actual pressure but when output fuel line is disengaged and engine cranked - fuel pours out - and fuel pump is heard pressurizing when key on.

Couldn't get to the starting fluid though so not sure about that.

When is stalls check engine light flashes once then stays off.

I had to move the jeep before it got towed but couldn't do it myself. So I used first gear and the starter...not so good but no one was around! I need this truck by friday morning. Thanks for helping
Expert:  Amedee replied 5 years ago.

What I would like you to do, is see if we have spark when this happens.

 

You can use a simple spark tester that you can get at your local auto parts store.

 

Let me know!

Customer: replied 5 years ago.
I have spark.
Expert:  Amedee replied 5 years ago.
Ok... good!

For this thing to run, all we need is spark, fuel and compression. SO if we have spark (and awsuming we have compression because it runs once in a while so that leads me to believe the motor is in good shape), then it should run on starting fluid.

Try some starting fluid into the intake or throttle body and let me know if it runs.
Customer: replied 5 years ago.
I haven't had a chance to get my roomate to help me crank the engine while I spray the starting fluid. But I will do this today hopefully and get back to you. If it runs this means I am not getting fuel right? Clogged fuel filter or bad pump? Is it possible for the pump to prime once and quit? Or would that be the ecm's fault? Sorry I haven't been able to get back to you been super busy.
Expert:  Amedee replied 5 years ago.

Thats ok...

 

Yes, if it runs on starting fluid, then we have a lack of fuel.

 

If it does not run on starting fluid, we may be missing spark.

Customer: replied 5 years ago.
ok, I started my jeep and it actually ran! I drove it around the block with no problems however, when I turned it off and tried to restart it - it started and ran for a bit struggling to stay running and then died. The starting fluid thing doesn't work apparently. The jeep has 200,000 miles on it. Could it be sucking in some sediment from the bottom of the tank not allowing good flow?
Expert:  Amedee replied 5 years ago.

Well if it were, it should have ran when starting fluid was sprayed into the intake.

 

Did it have spark?

Customer: replied 5 years ago.
ok,
Well it has spark because I was driving it around the block.
I parked it and let it run idle for a few minutes then, turned off the engine.
Then I went to start it back up and it ran for 2 seconds and then died again.
I dropped the fuel tank and looked for sediment build-up at the bottom and replaced the filter connected to the pump, as well as the main fuel filter. I also blew out all the fuel lines to make sure there is no obstruction.
I replaced the ignition coil, wires, plugs, cap, and rotor.
After all that it ran very well for about one minute and then started to sputter and idle raced up to about 2,000 and then back down again, sputtering and struggling to stay running.
Expert:  Amedee replied 5 years ago.
What is fuel pressure when this happens?
Customer: replied 5 years ago.
Fuel pressure starts at 31 psi when key on

When engine starts it slowly goes down to zero and engine dies

Immediatley after engine dies, fuel pump buzzes and pressure goes back up.
Expert:  Amedee replied 5 years ago.
Are we loosing power to the fuel pump? Do you need know the color wire that powers up the pump?
Customer: replied 5 years ago.
How would I be losing power to the pump in that way? I can put a volt meter to the harness or try and back-probe the connection to get a reading...
Expert:  Amedee replied 5 years ago.
Yes.. that would work. Or you can use a test light. Although, a voltmeter would be better.
Customer: replied 5 years ago.
Aha! I have 6.3 volts at the harness. Shouldn't it have at least battery voltage? Maybe bad fuel pump relay?
Expert:  Amedee replied 5 years ago.

YES!

 

Are you on the wire that powers up the fuel pump?

 

If so, then yes... it is possible!

Customer: replied 5 years ago.
I am probing the black and blue wires. I see a green wire with red tracer but this must be the reference wire...OK so I will get a new relay and get back to you tomorrow.
Expert:  Amedee replied 5 years ago.
Ok.. sounds good!
Customer: replied 5 years ago.
I replaced the fuel pump relay

No change in condition

Voltage remains at 6.3v

What's next?
Expert:  Amedee replied 5 years ago.
Where are we testing for voltage? Before or after the relay?
Customer: replied 5 years ago.
After the relay, down by the fuel pump harness connection
Expert:  Amedee replied 5 years ago.
What color wire are you on?
Customer: replied 5 years ago.
Black and blue
Expert:  Amedee replied 5 years ago.

MMhhh...

 

Maybe its because of the fuel pump ballast resistor.

 

 

LOCATION

A ballast resistor is installed in-line between the relay and the fuel pump.

OPERATION

The Engine Controller operates the fuel pump through the fuel pump relay during all operating conditions. This will be except for wide open throttle (WOT) and high engine loads. The ballast resistor reduces voltage to the fuel pump, reducing the level of fuel pump noise.

When the ballast bypass relay is energized, voltage is applied to the fuel pump through the ballast resistor. During WOT and high load operation, the Ballast Resistor Relay is de-energized and the ballast resistor is bypassed

 

LOCATION

The ballast bypass relay is located on a bracket connected to the Power Distribution Center.

OPERATION

Voltage is supplied to the fuel pump through the ballast bypass relay during heavy load or wide open throttle (WOT) conditions.

Voltage is supplied to the fuel pump through the ballast resistor, except during heavy load or wide open throttle (WOT) conditions. The ballast bypass relay is controlled by the Engine Controller.

The Engine Controller energizes the ballast bypass relay by switching the ground circuit to the relay (on-and-off). Battery voltage for the bypass relay is supplied through the fuel pump relay.

Customer: replied 5 years ago.
So should I try a new ballast bypass resistor and let you know? Would this be available at a parts chain or dealer only?
Expert:  Amedee replied 5 years ago.

Well, Not just yet.

 

Lets figure this out.

 

Lets make sure we are on the right wire.

 

I just double checked

 

Back my the gas tank, we should be on a dark green with a red stripe wire.

 

.

Expert:  Amedee replied 5 years ago.
The wire changes color after the connector back by the fuel tank. (According to my diagram). It changes into an orange wire.
Customer: replied 5 years ago.
I tested the green wire with red tracer and black wire...

With key on I get 12.4v (battery Voltage) but only for a second and then 0.0volts

Funny thing is I get a negative reading on these wires both ways I put the test leads.

I also hear the fuel pump relay click once when key turned on.
Expert:  Amedee replied 5 years ago.

So you get power on this wire when you turn the key on and thats it.... correct?

 

After it gets power for a second or two, then it goes to 0 volts even when cranking... correct?

Customer: replied 5 years ago.
Correct
Expert:  Amedee replied 5 years ago.

OPERATION

The Engine Controller energizes the fuel pump through the fuel pump relay. Battery voltage is applied to the relay from the ignition switch. The relay is energized when a ground is provided by the Engine Controller. The relay is located in the Power Distribution Center next to the coolant recovery bottle.

 

So it sounds like the fuel pump relay is powering up the fuel pump when the key is turned to the on position. But the fuel pump relay is not being engaged form the computer. I would like to confirm this.

 

I would like to you go to the fuel pump relay and check for a ground coming into this relay while you are cranking the engine over. You are going to want to see if the red wire with black stripe going into the relay is being pulled to ground while cranking. You might have to gain access to the back of the relay to test this. Leave the relay plugged in while cranking

 

 

The relays are located inside the Power Distribution Center. The Power Distribution Center is located next to the coolant recovery bottle

Customer: replied 5 years ago.
I checked the wires going to the fuel pump relay inside the distribution box however,
I don't see a redwire with black stripe - only see a solid red wire.

On the ballast resistor relay mounted on the outside of the box has a red wire with black stripe.

I have an LED test light with positive and negative diodes so this was easy. The test light showed ground with key off then switched to power with key on. During cranking it stayed power until engine started and immediately switched to gound.
Customer: replied 5 years ago.
Did I make a mistake or, is this a real mystery?
Expert:  Amedee replied 5 years ago.
Just so I am sure, were you on the red wire at the fuel pump relay? Or were you on the red wire with black stripe by the ballast resister?
Customer: replied 5 years ago.

I tested both.

 

The solid red wire on the fuel pump relay - this wire was power during the entire testing process. It never changed to ground.

Expert:  Amedee replied 5 years ago.
For some reason, my diagrams are not matching what you have on your vehicle. I will leave this question open for other experts.
Customer: replied 5 years ago.
So is this it? Am I on my own because of inacurate diagrams? I appreciate the help but this is turning out to be a dissapointment!
Customer: replied 5 years ago.
So is this it? Am I on my own because of inacurate diagrams? I appreciate the help but this is turning out to be a dissapointment!

Customer: replied 5 years ago.
Amedee - It'sCustomeragain...

So I tried a new ECM and that didn't work

I started the jeep and it had 31 psi - then slowly started going down again - until I pumped the throttle and hit WOT for a second WHEN IT HIT WOT FUEL PRESSURE SPIKED BACK UP TO AROUND 35 PSI

When I let go of the throttle fuel pressure went to zero and immediatly recharged pressure after it died. Then the fuel pressure recharged but this time it went to 40 PSI.
What is happening?!?!
Expert:  Amedee replied 5 years ago.

Does fuel pressure bleed off when the engine is off? Or is this when it is running?

 

When the engine died, what was fuel pressure at?

Expert:  bill replied 5 years ago.

hi i'mbill

i have 21 years with jeep/dodge/chrysler as a diagnosis tech i have read the questions and replys 31 psi isn't enough pressure for your jeepthe pressure is around 45 - 50 psi, so with that said and with the pressure dropping as it does i first want you to TEMPORALLY bypass the ballast resistor by fashoning a jumper wire with a small piece of wire and 2 male spade terminals put 1 spade on each end of wire after you have stripped the ends of insulation nad connect the wire inplace of the ballast resistor if the jeep now runs the resistor is likely bad (i have seen a few resistors fail and they do create a start and stall condition as the resistor is only used after start up we run full battery voltage while the key is in the "start " position and switches to the resistor in the "run" position) if not then i would suspect a bad fuel pump and filter, first i would change the fuel filter and see if it runs if it is clogged the fuel pump may be coming apart and leaving debris in the filter.

 

i am here to help if you want it and i don't give up easily, my replys to your question are based on info you give me it must be accurate or the answer will send you off in the wrong direction i will look up the fuel pump wiring and wait for your reply

Customer: replied 5 years ago.
Hi Bill,

IT WORKED! I jumped the two terminals and my jeep stayed running with no hesitation.

Is it safe to keep these terminals jumped for a quick trip in my jeep to the dealer parts counter?

Funny thing is that everone at the dealer has no idea what this part is!
Expert:  bill replied 5 years ago.
i would think yes BUT you do run the risk of damaging the pump, many of the jeep parts counterpersons wouldn't remember this as we stopped using it around 1996 or 1997 you may have to be patient with them as it may be buried in the parts catalog, it used to be called a fuel pump ballast resistor, and likely will need to be ordered,i seem to remember a bulletin of some type( i am trying to find it but our older bullitens are not cataloged very well) that elimenated the resistor i think it used a jumper wire and a new fuel pump if you have the dealer look up a fuel pump it MAY pop up in the computer to remove the resistor wwhen installing the pump.
Expert:  bill replied 5 years ago.

i found the bulletin !!you have an XJ

NO: 14-14-93 Rev. A

SUBJECT: Fuel Pump Noise

DATE: Dec. 31, 1993

THIS BULLETIN SUPERSEDES TECHNICAL SERVICE BULLETIN NO. 14-14-93 Rev. A DATED DEC. 3, 1993 WHICH SHOULD BE REMOVED FROM YOUR FILES. CHANGES ARE HIGHLIGHTED WITH **ASTERISKS**

SYMPTOM/CONDITION:

Excessive fuel pump noise (whine). The noise is loudest when heard from the rear seat.

PARTS REQUIRED:

Quantity

Part No.

Description

1

52018387

Fuel Pump Module (XJ)

**1

52018390

Fuel Pump Module (YJ) 15 Gal.**

1

52018391

Fuel Pump Module (YJ) 20 Gal.

 

REPAIR PROCEDURE:

This bulletin involves eliminating the fuel pump ballast resistor on XJ vehicles, and installing a new design fuel pump on XJ and YJ vehicles.

FOR XJ ONLY (YJ-Proceed to Step 3)

  1. Disconnect the negative battery cable.
  2. Locate the fuel pump ballast resistor bypass relay which is attached to the Power Distribution Center. Cut the 18 gauge dark blue wire at pin 5 of the relay and seal the harness end of the wire with electrical tape. This will eliminate the ballast resistor circuit to allow system voltage to the pump at all times.

    FOR XJ & YJ

  3. Using the procedures outlined in the appropriate Service Manual, remove the existing fuel pump module and install the pump module listed above.
bill, ASE Certified Technician
Category: Jeep
Satisfied Customers: 951
Experience: 21 yrs in the field 19 with Dodge Chrysler Jeep expert in electrical drivability
bill and 2 other Jeep Specialists are ready to help you
Customer: replied 5 years ago.
Thanks Bill!
I'm so happy to have a running vehicle again.

Thanks also for the bulletin.
Expert:  bill replied 5 years ago.
your welcome

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