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94 grand cherokee fuel problem

U

untamedrose

NAXJA Forum User
Location
Kingsburg, California
I need help with 94 grand cherokee fuel problem. Intermitent start, was told it was fuel pump, replaced it 6 months ago but problem was still there. So I put new filter, problem was sill there. Replaced relay fuse, still there and getting worse. Replaced cranck shaft passion sensor. Problem continued and got worse. So I replaced fuel pump again,was told it must have been a week pump. Now no start, but it does try.So I replaced coil pick-up, coil. NO start. However it will start with starter fluid. I am at a loss, can't seam to find the problem. Any help would be great!
 
untamedrose said:
.......However it will start with starter fluid......
Click to expand...
This pretty much narrows it down to the fuel system.
I suspect it's a bad fuel pressure regulator, or perhaps
a split in the upper soft hose running from the fuel
pump to the hard line. A fuel pressure test might tell
you for sure...
 
Common problem on ZJ's.. seems to be moreso on early ZJ's.

Turn the ign switch on..not to start.. and wait. If you start hearing a series of clicks from underhood verify it's your fuel pump relay. After the clicking it should start.

This narrows it down to your ECM.. theres a fix that involves soldering. Or you can send your ECM to a guy or two who do this service on ebay.
 
It does click when I turn the key to on. I pulled the fuel pump relay fuse and jumped with a paper clip with the key on, the pump runs. Have not checked the full pressure yet, I was told if there is fuel in the fuel rail, then there is good pressure. But I feel I still need to check how much pressure I'm getting. This is driving me nuts, would run her off a cliff but she wont start(so thats out)LOL
 
Are you replacing just the fuel pump, or the whole fuel pump assembly ?

What brand of fuel pump did you install ?
 
I replaced the fuel pump assembly twice and the fuel filter.
I will have to look up what the brand is.

If there is anything else I should replace in the fuel system, I will.
Just need someone to brain storm the problem.
My brain and bank are feed up!!!
 
Cheap fuel pump assemblies are well proven to have a short and miserable lifespan. AirTex is one of the main offenders. Have you tested the fuel pressure 20 minutes after shut-off, and when running ?

Genuine Jeep, Carter and Bosch are the only brands of fuel pump assembly to consider, unless you enjoy dropping the fuel tank every 12-18 months.
 
would check it running and 20 min. after (IF I COULD GET IT TO START)
but I did buy a (cheap auto parts .com) fuel pump
I had them send me a new one months later becuse I was still having problems.
It was still under warranty, so no charge.
 
untamedrose said:
It does click when I turn the key to on. I pulled the fuel pump relay fuse and jumped with a paper clip with the key on, the pump runs. Have not checked the full pressure yet, I was told if there is fuel in the fuel rail, then there is good pressure. But I feel I still need to check how much pressure I'm getting. This is driving me nuts, would run her off a cliff but she wont start(so thats out)LOL
Click to expand...

Fuel in the rail without pressure or the wrong regulated pressure is just fuel in the rail. Instead of throwing parts at it test it, thats what I meant by expensive advice :). Fuel pressure testers are cheap, you don't need a $nap on brand for this.

After you know you have good pressure you would test if the injectors are actually firing and letting gas through. Noid light will help with this, google it.

Overland is obviously a ZJ guy, our XJ's have different sensors that can cause a no start.
 
untamedrose said:
would check it running and 20 min. after (IF I COULD GET IT TO START)
but I did buy a (cheap auto parts .com) fuel pump
I had them send me a new one months later becuse I was still having problems.
It was still under warranty, so no charge.
Click to expand...

I wanted to add that fuel pumps are not a part to go cheap on. Getting stranded off the beaten path results in long walks in the woods around here, and tow bills. :):)
 
How can I tell if it's the cheap fuel pump?
I do have the first one they sent, that I pulled out.

Hate to drop that tank again, but I will if that's the fix.
Each time I dropped it, I broke a fitting and had to replace it
 
So no pressure and you still have gas in the fuel rail ? Pump primes with key in on position ?

If so, I would test the pressure regulator, been awhile but it is a vacuum operated part. Check that vac line to the regulator. You can tap on regulator and see if it won't break loose. You can hook up a hand vac pump to regulator and test too.

Testing pump is easy enough. Take the output line off somewhere before the filter and put it in a can or something and turn key to on position and see if fuel is being pumped. 2 people makes it easier.
 
Last edited:
well it stopped again... Ran for three days then started dieing again.
I AM AT A LOSE
there is fuel pressure in the rail.
I have cleaned all the fuses
I cleaned the ECM and PCM conectors
with electric cleaning spray
and put DI-Electric grease on them.
still will not stay running
runs, dies,restarts right away then dies again.
HELP.....
 
Here is some code info to check out as well. Seems to me that some kinda code might show up if it was sensor related.



To display codes cycle the ingition key On-Off-On-Off-On within three seconds. Count the number of flashes, first digit, pause then second digit will be displayed in a series of flashes. (2 flashes, pause, 1 flash = 21)

11 - No Crank Reference Signal At PCM (Crankshaft Position Sensor)
12 - Battery Disconnected Within last 50 Key-on cycles
13 - No Change In MAP Sensor
14 - MAP Voltage Too Low Or Too High
15 - No Vehicle Speed Sensor Signal
17 - Engine Is Cold Too Long
21 - O2 Sensor Signal At Center Or Signal Shorted To Voltage
22 - ECT Sensor Voltage Too Low Or Too High (ECT = Engine Coolant Sensor)
23 - Charge Air Temperature Sensor Voltage Too High Or Low (Intake Air Temp Sensor)
24 - Throttle Position Sensor Voltage Too High Or Too Low
25 - Idle Air Control Motor Circuit Shorted
27 - Injector Control Circuit Signal Not Responding Correctly.
31 - EVAP Purge Solenoid Circuit Open Or Shorted
32 - EGR System Failure
33 - A/C Clutch Relay Circuit Open Or Shorted
34 - Speed Control Solenoid Ciruit Open Or Shorted (Vacuum Or Vent)
37 - Torque Converter Clutch Solenoid Circuit Open Or Shorted
41 - Generator Field Not Switching Properly
42 - Auto Shutdown Relay Control Circuit Open Or Shorted Or No ASD Voltage
44 - Battery Temp Sensor Voltage Out Of Limit
45 - Overdrive Solenoid Circuit Open Or Shorted
46 - Charging System Voltage Too High
47 - Charging SYstem Voltage Too Low
51 - O2 Sensor Signal Stays Below Center (Lean)
52 - O2 Sensor Signal Stays Above Center (Rich)
53 - Internal PCM Failure
54 - Sync Pick-Up Signal Not Detected (Camshaft Position Sensor/Ignition Pickup)
62 - PCM Failure SRI Miles Not Stored
63 - PCM Failure EEProm Write Denied
55 End Of Codes

These codes are good for years 93, 94 and 95.

The above procedure will work for 96 and up but be aware an OBD II scanner will be needed as the above codes could have multiple meanings.


Transmission codes for 42re and mabye others, same routine but displayed via the overdrive light.

11 - Engine RPM Input
12 - Output shaft sensor input
13 - Vehicle speed input
14 - Governor pressure sensor input
15 - Throttle position sensor input
16 - Transmission fluid temp input
17 - Overdrive override switch input
18 - System voltage
19 - Internal fault in module
21 - Governor pressure solenoid output
22 - Overdrive solenoid output
23 - Converter clutch solenoid output
24 - Overdrive override lamp output
25 - Internal fault in module
26 - Governor pressure sensor offset drift
55 - end of codes
 
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