No Power to Fuel Pump?? - JKowners.com : Jeep Wrangler JK Forum
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post #1 of 10 Old 10-22-2017, 02:21 PM Thread Starter
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No Power to Fuel Pump??

Folks, just installed a rebuilt 3.8l engine in my 08 Wrangler X (JK). Initially a no crank because of fuel. Fuel pump fuse and relay are both good and the relay closes when the key is turned to run. If I pin the fuel pump blue/red wire and apply power the pump runs and the engine starts and idlest. One code on Inlet Air Temp high. New sensor ordered. This eliminates the Cam & Crank sensors in my mind. Are there other potential sensors or subsystems that could be interrupting the fuel pump hot side?
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post #2 of 10 Old 10-22-2017, 03:27 PM
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How did you verify the fuel pump relay is closing when you turn the key on?

2008 Unlimited Rubicon Automatic
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post #3 of 10 Old 10-22-2017, 07:09 PM
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This is more than likely a TIPM issue
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post #4 of 10 Old 10-22-2017, 08:31 PM Thread Starter
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I felt the relay click when the key is turned to run. To be sure to eliminate the relay as the potential problem, I replaced with a new one. When that didn?t work I jumped the terminals with a wire with blade clips. I?m currently chasing the wire through the harness. Good so far to the ?T? joint of the harness at the base of the radiator. I?m assuming and will verify tomorrow that the Blue/red wire heads up to the Power Distribution Panel (fuse box). I have yet to find a good schematic that shows all connections and couplings.
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post #5 of 10 Old 10-22-2017, 08:31 PM Thread Starter
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What is a TIPM?
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post #6 of 10 Old 10-22-2017, 09:05 PM Thread Starter
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Just watched a YouTube video on jumping the M25(fuel pump) fuse from M7. My M25 slot is showing power even when the key is off. Based on that video, the output side of M25 leads directly to the fuel pump. If power is applied there and the fuel pump doesn?t run there is a connection issue. Is the wire that leads from the TIPM to the fuel pump a fused wire?
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post #7 of 10 Old 10-22-2017, 10:37 PM
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The "TIPM" is the Totally Integrated Power Module, or fuse box.

The fuel pump relay isn't accessible, so the relay you felt click and changed was not for the fuel pump, unless you completely disassembled the fuse box, un-soldered the relay, and soldered in a new one.

The M25 fuse slot should have power to it only when the fuel pump relay is closed.

The wire that leads from the TIPM to the fuel pump is supposed to be dark blue with an orange tracer. It is fused only in the TIPM.

2008 Unlimited Rubicon Automatic

Last edited by ronjenx; 10-22-2017 at 10:39 PM.
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post #8 of 10 Old 10-24-2017, 04:30 PM
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post #9 of 10 Old 10-24-2017, 06:22 PM
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I keep a couple of the Littlefuse Add-A-Circuit doomaflatchis in my glove box in case I get stuck on the trail. I carry wire strippers / crimpers on the trail and will just make up the connecter when the TIPM blows. I carry my handy SnapOn test light too. It must be 30+ years old now.

I think this is the part:

https://www.oreillyauto.com/detail/l...00zpa/4414323/
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post #10 of 10 Old 10-24-2017, 08:21 PM Thread Starter
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My solution was the jumper to the switched side of fuse M7. After pulling all the fuses and relays I popped off the top cover (not easy!!) and after feeding a wire up through a drain hole on the bottom I soldiered the wire to the appropriate pin. To leave the Jeep wiring harness intact I slaved a fused wire onto the dark blue/red wire leading to the fuel pump. The pump activates with the key in ACC or Run. While not elegant the car runs and the TIPM is as it was and the jumper is easily removed if the TIPM fails further. Thanks all for your input.
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