Fuel Pump Won't Stop Priming - Engine Won't Turn Over
05-30-2016, 08:11 PM
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JK Freak
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Fuel Pump Won't Stop Priming - Engine Won't Turn Over
Alright guys,
Long story short - my Jeep won' start and the fuel pump won't stop priming.
Long story long - I completed a 1 ton junkyard swap roughly a year ago and ended up running a TJ fuel tank and pump in my 2008 JKU. The fuel pressures were the same, it was easy to wire and all was good. When the Jeep hadn't ran in a few days I had to turn the key to the "ON" position and listen for the fuel pump to stop priming before the Jeep would turn over. After a week on the honeymoon, I come back and the pump won't shut off. It made me think that it wasn't able to build the necessary pressure, so I checked for leaks... No leaks. Then it made me think to see if the pump was producing any pressure at all, so I loosened the fuel line (Both on the pump side and engine side) and there seemed to be plenty of pressure. (Although I was not able at the time to properly gauge it.) All wires seemed tight, I disconnected the battery for a few minutes and tried again, I waited a few minutes to see if the pump would eventually turn off. I just don't know what else might be causing it. The engine just cranks without even a hint of turning over.
I still have the pump out of the JK tank. To be honest I can't remember the reason I am running the TJ pump over the JK one, but I am going to try that one to see if it works tomorrow.
I know this is a pretty specific scenario, but if anyone has any ideas, they'd be much appreciated.
-Chandler
Long story short - my Jeep won' start and the fuel pump won't stop priming.
Long story long - I completed a 1 ton junkyard swap roughly a year ago and ended up running a TJ fuel tank and pump in my 2008 JKU. The fuel pressures were the same, it was easy to wire and all was good. When the Jeep hadn't ran in a few days I had to turn the key to the "ON" position and listen for the fuel pump to stop priming before the Jeep would turn over. After a week on the honeymoon, I come back and the pump won't shut off. It made me think that it wasn't able to build the necessary pressure, so I checked for leaks... No leaks. Then it made me think to see if the pump was producing any pressure at all, so I loosened the fuel line (Both on the pump side and engine side) and there seemed to be plenty of pressure. (Although I was not able at the time to properly gauge it.) All wires seemed tight, I disconnected the battery for a few minutes and tried again, I waited a few minutes to see if the pump would eventually turn off. I just don't know what else might be causing it. The engine just cranks without even a hint of turning over.
I still have the pump out of the JK tank. To be honest I can't remember the reason I am running the TJ pump over the JK one, but I am going to try that one to see if it works tomorrow.
I know this is a pretty specific scenario, but if anyone has any ideas, they'd be much appreciated.
-Chandler
05-30-2016, 08:33 PM
#2
JK Jedi Master
From what I just read about the TJ fuel pump, it runs all the time the ignition is on. When fuel pressure reaches a certain level, excess fuel is dumped into the tank through the pressure regulator.
The JK fuel pump operates the same way.
The JK fuel pump operates the same way.
05-31-2016, 06:21 AM
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JK Freak
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Hmmm... I can usually hear it kick off after a second of two when the key is in the on position before starting. I'll see what I can figure out today
05-31-2016, 06:42 AM
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After a little more research I might be leaning towards a fuel pump relay that is somehow stuck open, or an ECM issue. I'm praying this is a $9 fix, not a $400 fix.
Any other signs that the ECM might be bad?
Any other signs that the ECM might be bad?
05-31-2016, 07:22 AM
#5
JK Jedi Master
Anyway, the JK fuel pump relay is soldered to the TIPM circuit board. It sends power to the fuel pump all the time the ignition is on. I'll check that out later with a stethoscope to make sure. I have never heard my JK's fuel pump running, so I can't say I have noticed it turn off when pressure is built.
05-31-2016, 09:28 AM
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Relay stuck open? If it's stuck open, the fuel pump won't run at all.
Anyway, the JK fuel pump relay is soldered to the TIPM circuit board. It sends power to the fuel pump all the time the ignition is on. I'll check that out later with a stethoscope to make sure. I have never heard my JK's fuel pump running, so I can't say I have noticed it turn off when pressure is built.
Anyway, the JK fuel pump relay is soldered to the TIPM circuit board. It sends power to the fuel pump all the time the ignition is on. I'll check that out later with a stethoscope to make sure. I have never heard my JK's fuel pump running, so I can't say I have noticed it turn off when pressure is built.
05-31-2016, 07:26 PM
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After replacing the fuel pump relay (Plug in that goes right into the circuit breaker box) the problem was still there. I ran through the wires from the pump up to the engine bay before finally taking the fuse box out to inspect the wiring harnesses that attach beneath. There it was, one wire that has somehow fallen out of a harness. When set back in place, the jeep started right up.
Case Closed
Case Closed
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05-31-2016, 07:40 PM
#8
JK Jedi Master
After replacing the fuel pump relay (Plug in that goes right into the circuit breaker box) the problem was still there. I ran through the wires from the pump up to the engine bay before finally taking the fuse box out to inspect the wiring harnesses that attach beneath. There it was, one wire that has somehow fallen out of a harness. When set back in place, the jeep started right up.
Case Closed
Case Closed
I'm a little confused about that fuel pump relay you replaced, though.
My 2008 JK doesn't have a fuel pump relay in the TIPM (fuse box), visible from the top. It's soldered to a circuit board, deep inside the TIPM.
06-06-2016, 03:57 PM
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Glad you got it running. No telling what that loose wire went to.
I'm a little confused about that fuel pump relay you replaced, though.
My 2008 JK doesn't have a fuel pump relay in the TIPM (fuse box), visible from the top. It's soldered to a circuit board, deep inside the TIPM.
I'm a little confused about that fuel pump relay you replaced, though.
My 2008 JK doesn't have a fuel pump relay in the TIPM (fuse box), visible from the top. It's soldered to a circuit board, deep inside the TIPM.
06-06-2016, 04:16 PM
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So I have been fighting to keep this wire in the connector for a week now. I have tried everything from re-pinning to a dab of super glue and I just can't keep a steady connection.
Next step: Get a new harness with a few inches of wires attached, then just spice those wires to my existing wires.
Problem: I only have half of the wiring harness part number and cannot find it anywhere. The tag that wraps around the bundle of wire has been partially torn and leaving me with the last 5 digits of the part number "001AC" Could anyone please take a look at their harness to see if their part number also ends in "001AC" and if so, fill me in with the preceding numbers?
I stopped at a salvage yard on the way home from work today and found the same connector that was in an 08 JKU X. When I got home, I found that even though it was the same connector, there were fewer wires connected and they were in different spots. I drive an 08 JKU Sahara.
Thanks in advance.
Next step: Get a new harness with a few inches of wires attached, then just spice those wires to my existing wires.
Problem: I only have half of the wiring harness part number and cannot find it anywhere. The tag that wraps around the bundle of wire has been partially torn and leaving me with the last 5 digits of the part number "001AC" Could anyone please take a look at their harness to see if their part number also ends in "001AC" and if so, fill me in with the preceding numbers?
I stopped at a salvage yard on the way home from work today and found the same connector that was in an 08 JKU X. When I got home, I found that even though it was the same connector, there were fewer wires connected and they were in different spots. I drive an 08 JKU Sahara.
Thanks in advance.