jeeper jason

My fuel pump fuse blows when I shift my jeep in reverse but only after extended periods of driving , I am assuming I have a short but can not find it, have a big road trip coming up and need to fix it ASAP, plz help!!!!

jeeper jason

Anybody?

jeeper jason

Anybody?

freegdr

Gotta give it a little time for answers ...what have you tried in ways of detecting problem ?

Batman33165

Maybe wires touching each other?

jeeper jason

Checked the wires the best I could, but didn't have time to rip up panels and all the exposed wires were pretty muddy

rompnXJ

gotta love the weird electrical problems on the 97+ XJ's... mine blows the fuel pump fuse if I turn the blower motor on. have yet to figure it out lol.

You'll need to bust out the electrical diagrams and physically inspect the NSS circuit and the fuel pump fuse circuit, seems like there's an area where the 2 circuits are shorting to each other; intermittent shorts are difficult to find.

CCKen

Both the fuel pump power circuit wire and the reverse circuit wire of the transmission range sensor (NSS) pass through connectors at the transmission dipstick tube. There's a group of three connectors there. The wire harness looms for these connectors are usually tie wraped to each other and to the tranny dipstick tube. A real cluster phuc. There's a lot of movement of the engine/tranny in this area that may cause wire chafing.

Perhaps you should examine the wires/looms in this area for chafing, to the point where you cut the looms loose from each other and the dipstick tube inorder to get a good look.

jeeper jason

Yeah, all my jeep problems have either been cause by me from offloading or electrical, and ppl on my face book chat group suggested maybe a short to my reverse light wires

jeeper jason

I gave those a once over earlier but now that I have more time I will probably start over and do it better, any other problem areas to check out?

CCKen

Which fuse is blowing BTW? F22, 15A, in the PDC or F11, 20A, in the JB?

It has to be a dead short in the fuel pump power wire (F22, 15A, in the PDC) to blow the fuse. Were there any mods or repairs done to the left side of the Jeep along floor level, from the cargo bay to under the dash, that could have run drills through wire bundles or screws poked into wire bundles. The fuel pump power wire runs along the left side. Body twisting while in reverse may be just enough to short a bare wire out.

To satisfy the chat group, pull the left back up lamp bulb out and see if it helps. This would open the left side reverse light circuit. The left reverse lamp and the fuel pump share the same ground (G302) behind the spare tire support bracket. I doubt this will help but what the hell...

Here's a pic of the location of G302:

jeeper jason

Not so solid on my electronics so I'm gonna try to answer ur questions the best I can, it's a 15watt fuse located in the engine bay



It's the blue fuse that is pulled and miss colored compared to the rest, as far as repairs, as far as I know nothing was done to the drivers side, it was backed into awhile back and the rear fender is pretty dented up below the fuel filler door, I did not have it repaired since it was only cosmetic, I have not noticed anything from the previous owner

CCKen

Looks like the one. Based on the different shade of Blue I think this fuse has been replaced before. The previous owner knew about this didn't he...

CCKen

If you want, try this:

It will involve wiggling wiring to see if you can trigger the fuse to blow.

You'll need:

A helper
A 15 Amp, 12 volt, S.P.S.T. toggle switch
Two crimp type, .250" wide. blade terminals,
Wire crimpers
15 Amp Blow and Glow [not the actual name] type mini fuses.

See pic for image of the switch. The blade terminals are available anywhere, as I recall they are for 18 ga. wire. The blow and glow mini fuses are at O'reilly Auto Parts, but may be at other auto parts stores. These fuses have a LED that lights up when the fuse blows. Wire crimpers are also available at the auto parts stores. The switch is available at the auto parts stores.

Transmission in Park. Assemble the switch. Remove the fuel pump relay. Remove the existing 15 Amp mini fuse (F22) and insert a 15 Amp blow and glow fuse. Turn the switch to OFF then insert the blades into the relay base, pin cavities 30 and 87 (as in the pic), have the helper turn the swich on, the fuel pump will run continuosly off the battery. Have the helper monitor the mini fuse to see if/when it blows while you crawl under the Heep and wiggle the fuel pump harness at the fuel pump, and wiggle the harnesses at the connectors by the tranny dipstick, the harnesses along the firewall...use your imagination.

You may want to try this with the transmission in Reverse (engine not running) to see if it makes a difference.

~~~~~~~~~~

I made this switch setup to test my fuel pressure before and after I changed my fuel pump module. After this I also made a 40 Amp rated switch setup to jumper every ISO type relay in my Heep.

jeeper jason

I blew the original fuse months ago and didn't think anything of it, I recently blew two more

And I will defiantly have to try that setup with the switch and "blow and glow" fuse as soon as I get a chance, it is difficult to find time to do things like this when it is my DD, hopefully will be able to tomorrow, thank you for all your help