Jeep Repair Problems? Ask a Mechanic for Answers ASAP
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!
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.
Well if it were, it should have ran when starting fluid was sprayed into the intake.
Did it have spark?
Are you on the wire that powers up the fuel pump?
If so, then yes... it is possible!
Maybe its because of the fuel pump ballast resistor.
A ballast resistor is installed in-line between the relay and the fuel pump.
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
The ballast bypass relay is located on a bracket connected to the Power Distribution Center.
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.
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.
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?
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
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.
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?
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
i found the bulletin !!you have an XJ
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**
Excessive fuel pump noise (whine). The noise is loudest when heard from the rear seat.
Fuel Pump Module (XJ)
Fuel Pump Module (YJ) 15 Gal.**
Fuel Pump Module (YJ) 20 Gal.
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)
FOR XJ & YJ