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Unread 10-24-2011, 11:58 AM   #1
msan65
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Join Date: Oct 2011
Location: Elk Grove Village, IL
Posts: 2
Not enough power getting to fuel pump

I've been working on my '95 Jeep Wrangler 2.5 and just replaced the fuel pump only to find out it's not getting the full 12V from the battery... It's only getting about 7.4. Anyone have any ideas on why that may be?

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Unread 10-24-2011, 12:39 PM   #2
Apollo12227
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1992 YJ Wrangler 
 
Join Date: Oct 2009
Location: Orlando
Posts: 2,661
No clue, what wire are you getting your reading from? The top of the tank? Rear driver's frame rail?
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Unread 10-24-2011, 12:58 PM   #3
msan65
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I'm getting my reading from the connector located at the top of the tank.
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Unread 10-24-2011, 01:01 PM   #4
AaronJ
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1992 YJ Wrangler 
 
Join Date: Oct 2010
Location: New Orleans
Posts: 290
My first thought would be the fuel pump relay. Possibly burned contacts on it. Try swapping it with your horn relay or one of the other relays for test purposes.

Located in the power distribution center by the battery.
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Unread 10-24-2011, 01:11 PM   #5
Que89YJ
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1989 YJ Wrangler 
 
Join Date: Apr 2008
Location: Detroit, Michigan
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Yep, I have an idea. You are reading it wrong. If you are trying to read the voltage the key being in the on position is not enough. If you are seeing 7 volts you are probably measuring the fuel level voltage and not the power to the pump. The ASD relay shuts down power to the fuel pump even with the key on when the Jeep is not running. In order to read the voltage you need to jumper pin 30 to 87 in the relay socket with a small wire. Make sure you check power at the pump across the ground in the connector and then to chasis. The ground for it is up in the front by the bracke release bracket and its common for it to loosen up. Check all your fuses first before you do anything. One more common fuel pump wiring problem is broken wire where it goes through the chasis in the back.
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Unread 10-24-2011, 02:31 PM   #6
Apollo12227
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1992 YJ Wrangler 
 
Join Date: Oct 2009
Location: Orlando
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I agree with Que, when troubleshooting a fuel pump issue I messed up the same way and as Que said it sounds like you are reading the sending wire for your fuel gauge above reading the actual fuel pump voltage.
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