98 XJ no power to fuel pump
02-23-2017, 09:11 PM
#16
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18 is a 25 amp. From the fuse and relay legend that freegdr posted it looks like fuse fuse 19 is the one you would be looking at. Maybe my wiring diagram is wrong, it happens.
Last edited by Cornfed1; 02-23-2017 at 09:18 PM.
02-23-2017, 09:15 PM
#17
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Year: 01,01,99,98,97,97,96,94,90MJ,90MJ,86MJ
Model: Cherokee
Engine: 4.0
Okay yea I just came inside from checking and fuse 18 checks out good I will take apart the PDC tomorrow and inspect the ASD relay
02-23-2017, 09:34 PM
#18
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I looked at a few other wiring diagrams I have for same year, they say fuse 19 goes to the combination flasher. Found another 1 saying 18 is for the ASD relay but I have found that things can be mislabeled sometimes. The 1 I have that shows 19 for the flasher is a 15 A fuse.
02-23-2017, 09:39 PM
#19
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Year: 01,01,99,98,97,97,96,94,90MJ,90MJ,86MJ
Model: Cherokee
Engine: 4.0
Originally Posted by Cornfed1
I looked at a few other wiring diagrams I have for same year, they say fuse 19 goes to the combination flasher. Found another 1 saying 18 is for the ASD relay but I have found that things can be mislabeled sometimes. The 1 I have that shows 19 for the flasher is a 15 A fuse.
Some call the second one I circled 18
Either way the one circled in the first image is unused. So the next one is the 20amp for the ASD. In my case the fuse is good
02-23-2017, 09:50 PM
#20
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Year: 01,01,99,98,97,97,96,94,90MJ,90MJ,86MJ
Model: Cherokee
Engine: 4.0
So I tested fuse 18 and it's getting 12v pin 30 and 85 for ASD getting 12 volts. Green wire at fuel pump connector 0volts
02-24-2017, 08:22 AM
#21
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Year: 1999
Model: Cherokee
Engine: 4.0
F21 in the PDC is the fuel pump power (relay) fuse for a '98. See PDC layout pic below.
,
Here's some notes I took when testing my fuel pump relay:
.
Fuel pump circuit:
.
F11 in the JB powers the fuel pump relay control coil (and lots of other circuits).
.
I made up a jumper switch to test my fuel pump 10 Amp max draw by replacing the 15 Amp fuse with a 10 Amp fuse. This is beside the point, just wanted to show you using an ON/OFF switch (15 Amp) to run the pump.
,
Here's some notes I took when testing my fuel pump relay:
.
Fuel pump circuit:
.
F11 in the JB powers the fuel pump relay control coil (and lots of other circuits).
.
I made up a jumper switch to test my fuel pump 10 Amp max draw by replacing the 15 Amp fuse with a 10 Amp fuse. This is beside the point, just wanted to show you using an ON/OFF switch (15 Amp) to run the pump.
02-24-2017, 05:31 PM
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Year: 01,01,99,98,97,97,96,94,90MJ,90MJ,86MJ
Model: Cherokee
Engine: 4.0
Originally Posted by CCKen
F21 in the PDC is the fuel pump power (relay) fuse for a '98. See PDC layout pic below.
,
Here's some notes I took when testing my fuel pump relay:
.
Fuel pump circuit:
.
F11 in the JB powers the fuel pump relay control coil (and lots of other circuits).
.
I made up a jumper switch to test my fuel pump 10 Amp max draw by replacing the 15 Amp fuse with a 10 Amp fuse. This is beside the point, just wanted to show you using an ON/OFF switch (15 Amp) to run the pump.
,
Here's some notes I took when testing my fuel pump relay:
.
Fuel pump circuit:
.
F11 in the JB powers the fuel pump relay control coil (and lots of other circuits).
.
I made up a jumper switch to test my fuel pump 10 Amp max draw by replacing the 15 Amp fuse with a 10 Amp fuse. This is beside the point, just wanted to show you using an ON/OFF switch (15 Amp) to run the pump.
02-24-2017, 08:32 PM
#23
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Year: 01,01,99,98,97,97,96,94,90MJ,90MJ,86MJ
Model: Cherokee
Engine: 4.0
So now I have the pump running but the gauge is not working, and I'm not building any pressure to the fuel rail
02-25-2017, 07:12 AM
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Year: 01,01,99,98,97,97,96,94,90MJ,90MJ,86MJ
Model: Cherokee
Engine: 4.0
Originally Posted by freegdr
So if it was running here why did we go any furthur ?
02-25-2017, 09:51 PM
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Year: 01,01,99,98,97,97,96,94,90MJ,90MJ,86MJ
Model: Cherokee
Engine: 4.0
Originally Posted by freegdr
Confused 
Fuse blown again ?
Fuse blown again ?
02-26-2017, 09:49 AM
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Year: 01,01,99,98,97,97,96,94,90MJ,90MJ,86MJ
Model: Cherokee
Engine: 4.0
Yea it's full well at least 3/4