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hi man, I am going to replace my fuel pump module, so I decided to check what is the problem because it does not measure correctly my fuel gauge, besides my fuel pump turns off frequently, I am thinking about replace fuel pump (it gives me 46 psi at 60°C) and filter/regulator but I don't know if I could repair the sending unit ( i think is burn out)

if the sending unit is broke I am going to replace all module, do you think that it will work very well a Carter Mogul Federal fuel pump assembly ? will I have a problem if this module does not belong to mopar products ? I am afraid about the quality because I heard about a certain noise coming from the pump when you dont use an original replacement

thanks alot.
 

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These are just well known pumps in the aftermarket automotive industry. They cost $ 100 here in the USA. You can gut the innards of the OME assembly and install ones of these or you can remove the pump from the OEM assembly and re-install the OEM assembly and place an external operated fuel pump underneath the vehicle, for easier future replacement. I believe that the original pump is does not flow thru directly since it is a positive displacement type pump, so you cannot simply add an external pump to the underside without removing the old one first.
 

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Leak

I replaced the fuel pump on my 1997 Limited. Now it is leaking when I fill it up. I am damn near certain I got the seal seated correctly and the ring nice and tight. I guess the pump could leak out the top if it was cracked or defective. I'm pretty frustrated that I now have to drop my gas tank once again. Any ideas.
 

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I used to work at Walbro for three summers. Had I known then what I know now, I would have grabbed a few off the line for home use in the future.

Those plastic parts are probably the floats for level that have come free from the assembly. I used to have some floating in my ZJ tank. They sounded like ping pong balls on a hard stop in the garage with a full tank.

The dealer did my ZJ install for $562. If I need a swap in the future, I will be doing this myself.
 

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I have either a stock 2g eclipse turbo walbro or a 190lph walbro out of my talon that I replaced with a 255 walbro.. anyone know if this will work on my stock zj?
Not sure if it would need bigger injectors or anything to work with the different flow of the fuel pump.
Any help would be greatly appreciated as it would save me alot of money.
 

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Nice write-up.

When I purchased my new '94 ZJ I was disappointed at how quickly the factory hitch and skid plate developed surface rust, so I removed them, repainted them and reinstalled them. The re-paint has held up well over the years.

My practice is to use Loctite or anti-sieze on fasteners to aid future removal.

The image shows these skid plate / hitch studs + bolt threads w/ anti-sieze were still protected after ~13 years of New England usage.

A hint for those w/ the off-road package and the tow package, drop the hitch on one side and replace a nut to retain the skid plate, as shown in the image. Repeat for the other side.

This permits dealing w/ the hitch, then dealing w/ the skid plate. Both are a handfull by themself.



My experience was to impart imact force around the circumference of the large fuel pump retention nut, moving each impact roughly 180° apart, during both loosening and tightening. I found that it worked better in both directions then when tapping at only one spot.

Prior to removing the tank I siphoned most of the fuel out.



It was easy enough to remove the splash shield that exposes the filler hose clamps and made splitting that connection easier.



p.s. Any tips on where to find the cheap Chinese Walbro knock-offs?
 

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What if I did everything but depressurize the fuel system? I changed the filter on the bottom of the pump a couple weeks ago and it runs fine except for stalling once when I took it on the road for the first time in 6 months.
 

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The tank straps had some serious surface rust, especially where the foam pads attached to the skid plate presses against the tank strap.

The straps were sanded, painted and reused.

They still have plenty of meat left and the skid plate ensures the tank won't go anywhere.

One of the locking flange nuts on the tank bolts wasn't going anywhere. That bolt was cut for removal.

Both bolts and locking flange nuts were replaced. Loctite anti-seize was applied to the threads to prevent future immobility failure.

The bolts and nuts were a pain to obtain. The bolts weren't available from the local dealership.



 

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I've been searching around, and threads like this were all I've come up with. Does anyone have a diagram of the sending wire trace for the sender unit. My jeep was "totaled" in an accident and has since been repaired but the fuel sender stopped working at the time of the accident. The jeep took a pretty good hit, and I want to figure out at which point the sender has failed. I find it more likely it's a break, but not sure.

Thanks all,

Mike
 

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C304 is the gray plug left side under the dash. You can find it by the wire colors.

FUEL GAUGE
The fuel gauge gives an indication of the level of
fuel in the fuel tank. The instrument cluster circuitry
controls the gauge pointer position. The instrument
cluster circuitry calculates the proper gauge pointer
position based upon a fuel level message received
from the Powertrain Control Module (PCM) on the
Chrysler Collision Detection (CCD) data bus.
The PCM uses an input from the fuel gauge sending
unit and internal programming to decide what
fuel level message is required. The PCM then sends
the proper message to the instrument cluster on the
CCD data bus. If the PCM detects a short or open in
the fuel level sending unit circuit, it sends a message
on the CCD data bus that will cause the instrument
cluster circuitry to position the fuel gauge needle at
the Empty stop.
The fuel gauge sending unit is mounted to the electric
fuel pump module located inside the fuel tank.
The sending unit has a float attached to the end of a
swing-arm. The float moves up or down within the
fuel tank as the fuel level changes. As the float
moves, an electrical contact on the pivot end of the
swing-arm wipes across a resistor coil, which changes
the internal electrical resistance of the sending unit.
Refer to Group 14 - Fuel Systems for more information
on the PCM and for the fuel gauge sending unit
service procedures.

FUEL GAUGE SENDING UNIT
The fuel gauge sending unit contains a variable
resistor (track). As the float moves up or down, electrical
resistance will change. Refer to Group 8E,
Instrument Panel and Gauges for Fuel Gauge testing.
To test the gauge sending unit only, it must be
removed from vehicle. The unit is part of the fuel
pump module. Refer to Fuel Pump Module Removal/
Installation for procedures. Measure the resistance
across the sending unit terminals. With float in up
position, resistance should be 20 ohms. With float in
down position, resistance should be 220 ohms.
 

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So it goes through the PCM before the dash? I am getting a code that the sender is outside specified value or something. So this means I am looking for a short between the PCM and the sender, correct, not between the PCM and the cluster?

Thanks,

Mike
 

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So, this might sound like a dumb question and since you didn't address it, I'll presume it is.

But what about repressuizing the fuel line? You depressurized it. And drain it. Then it's full of air and no pressure. Once you reconnect everything do you just turn the key to start for an extra second to get the fuel line repressurized and fuel back up to the intake?
 

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So, this might sound like a dumb question and since you didn't address it, I'll presume it is.

But what about repressuizing the fuel line? You depressurized it. And drain it. Then it's full of air and no pressure. Once you reconnect everything do you just turn the key to start for an extra second to get the fuel line repressurized and fuel back up to the intake?
Let the key set on run for and extra second or two. You should hear the hum of the fuel pump running to pressurize the fuel lines. Wait until it stops before turning the key to start. It might take the engine a extra second to start the first time
 

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Easy way of reinstalling the tow package/skid plate

To add to this, for you guys who have the tow package and skid plate, it can be a pain to lift both of those into place by yourself and try to put the bolts/nuts on. I found that if you zip tie the hitch and skid plate together in the middle hole on each side you can lift the whole set-up up with the jack and then get the 4 corner bolts started then just cut the zip ties and tighten everything down.
 
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