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Fuel System question, Electric Fan Question

POSJ

NAXJA Forum User
This is on the Jeep in my signature. The Jeep ran fine all day long, it has always taken a few turns of the key to get it to start. But when my wife shut it off at the trailhead after the trip it wouldn't restart. The electric fan at the radiator was running which is weird. I went to the rear and didn't hear the pump priming. So we towed it home. Here is what I have found.

Fuel pump seems to be getting power. +4 VDC and -4VDC show when ignition switch is turned on. Are these the correct voltages? Are there any relays or solenoids that the electric radiator fan and the fuel pump share?

As long as I have owned XJ's I've never noticed the fan running before the Jeep was running. The control switches are all in the off position so the temp switch is the only thing I can think that might affect the fan. I tried starting the Jeep again today in my garage and the fan still runs. Something is fishy besides the fuel pump I think. All $.02 are welcome. Thanks

Tyler:us:
 
Hi.

Check the connection to the CTS in the thermostat housing. If that connection is screwed up the auxiliary fan will run. Could also be a stuck fan relay.

You should have more power at the pump--no ballast resistor since 93 or 94, IIRC. So, what is the battery reading between the posts? What is the voltage on the BATT side of the fuel pump relay?
 
Checked the voltage of the battery and it was 12.7 vdc. Checked voltage after the fuel pump relay and it was 4 vdc. Where is this voltage being lost if the relay is plugged directely into the power diverter box. I think before I dig into the main wiring harness I'm going to change the full pump with an OEM unit and see what the Jeep does. Any other ideas?
 
Ohh and II swapped the fuel pump relay with the fan control relay and neither issue changed so the relays are good.
 
Changed the fuel pump module today and it didn't fix the problem. Joe do you by chance have a factory service manuel for my turd? I'm thinking it's the ECU since, from what I can see in the Haynes, this is the only common link between the pump and the electric fan. Any advice would be appreciated. Thanks.

Tyler
 
Could be bad cables/grounds,have you checked for voltage drop?
 
Wound up being the Automatic Shut Down circuit...got it running but now the check engine light is on...it never stops...
 
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