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Greg
Greg, Technician
Category: Jeep
Satisfied Customers: 6806
Experience:  maintain jeep wrangler's for a off road rental company,
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I have a 2006 Wrangler Unlimited. 6 cylinder engine. Hit a

Customer Question

I have a 2006 Wrangler Unlimited. 6 cylinder engine.
Hit a bump the other day and it died due to lack of fuel. Would not restart. Decided to give it a try about 20-30 minutes later after sitting on the side of the road and it fired right up. Died 20 minutes later on my drive home, towed it to the house.
So today I changed the fuel pump, but it won't run. Cranks like a champ, but it's not getting any fuel. The new pump itself won't run.
Tested the pumps, new and old, by giving them direct power and they both ran. Plugged the harness back in, nothing. Relay is good, and the harness has power.
Testing with the old pump, it gets power at the top and bottom, but won't run when you turn the key to on.
Long story short, fuel pump is getting power but refuses to run when connected to the vehicle. Any ideas on what could possibly be causing this? Thanks in advance.
Submitted: 2 months ago.
Category: Jeep
Expert:  Greg replied 2 months ago.

Hi, I'm Greg (Indy-Tech).
Welcome to JustAnswer. I'm reviewing your question now, and will post back with your reply ASAP.
Rgds Greg.

Expert:  Greg replied 2 months ago.

If you can have the car connected to a scan tool and check for malfunction codes .

If no tools do the following for me .

Hand brake ON .

Crank engine over for 10 seconds and observe the RPM tachometer it shouls read 250rpm +/-50rpm .

If no readings then may well be a bad connection on the Crankshaft sensor or the sensor itself

Now you will need diagnostic tool to diagnose this issue .

If RPM shoe 250. then please let me know .

Kind regards Greg

Customer: replied 2 months ago.
One code popped up when we hooked it up to the scanner my brother has that works with his cellphone. P0463 High voltage on the fuel levelWe checked the crank sensor for resistance and didn't find any, so we did not change it.I let it crank for 10 seconds and I had no RPMs whatsoever.When I still had some pressure in the line before it relieved itself it would start and run for a few seconds with 0-250 RPMs before dying out.
Expert:  Greg replied 2 months ago.

Okay looks like a Crank sensor with you not having any readings from the Taco.

Do you have live data on your scan tool .

The code P0463 is just the fuel level sensor .this is due to you having the fuel pump disconnected .

Greg

Customer: replied 2 months ago.
I'll change the sensor in the morning and let you know.
Expert:  Greg replied 2 months ago.

Okay sounds good i will be here .

Greg

Customer: replied 2 months ago.
Replaced the crank position sensor, no change. Still not reading any rpms when cranking.The pump still will not even run for the 3 seconds it's supposed to when you turn the key to the on position, even though it's getting power.
Expert:  Greg replied 2 months ago.

And the Only code you have is P0463 .

What scan tool are you using .

Greg

Customer: replied 2 months ago.
Veepeak ODBII Diagnostic Scanner for Android. Connects to your cell phone via Bluetooth and interfaces with an app called Torque.There are no fault codes coming up.
Expert:  Greg replied 2 months ago.

Okay good .

Go into live data and see RPM data and crank over the engine do you see a reading .

Greg

Customer: replied 2 months ago.
it goes to 166.
Expert:  Greg replied 2 months ago.

Okay crank sensor is working, i would now see if you are having a security issue, is the security light ON or flashing when the ignition is switched to the ON position .

Greg

Customer: replied 2 months ago.
Security light? I'm not aware of having a security system.
Expert:  Greg replied 2 months ago.

Close all doors and then lock and unlock the door with the key .

Step in and try and start .

Then if no start try again with the Keyfob.

Try this then get back to me .

Expert:  Greg replied 2 months ago.

On the instrument cluster you will see aamber skis light on IF your Vehicle has this option.

Greg .

Expert:  Greg replied 2 months ago.

Crank engine and check you do have spark at the spark plugs .

Greg

Customer: replied 2 months ago.
No power windows or locks, no key fob, no chip in the key, no security feature.
Expert:  Greg replied 2 months ago.

Okay Michael do you have spark at the spark plugs when cranking over the engine .

Customer: replied 2 months ago.
Expert:  Greg replied 2 months ago.

okay good in the fuse box change over the HORN relay for the Fuel pump relay then try and start .

Did you check all fuses .

Greg

Expert:  Greg replied 2 months ago.

Still no start swap over the A/C relay for the Auto shut down relay and try and start .

Greg

Customer: replied 2 months ago.
First things I did. All the fuses were good and I also swapped the relay for the ASD just to make sure it wasn't bad either.
Expert:  Greg replied 2 months ago.

Okay with a test light check at the pump for power . no power then make your way back up the wiring harness .

But first when you switch on the ignition does the fuel relay switch on for two seconds ?

Greg

Customer: replied 2 months ago.
there is power reaching the pump, and yes, you can hear the relay switch on and off. The pump is brand new and runs with direct power applied to it.
Expert:  Greg replied 2 months ago.

Okay so the orange and red wire has power .

Now ground the black wire switch on the ignition will the pump now run

Customer: replied 2 months ago.
Alright, going to have to walk me through that one a bit. Where do I find it and what exactly should I do.
Expert:  Greg replied 2 months ago.

At the fuel tank where the fuel pump module is fitted is a plug did you check here for power on the Orange and red wire .

alongside is the Black splice into this to give ground .

Greg

Customer: replied 2 months ago.
that orange and red wire has power at the fitting that plugs into the fuel pump. There are four wires, power to pump, ground for pump, power to level, ground for level. What do you want me to do with the black ground wire for the pump?
Expert:  Greg replied 2 months ago.

Michael if you have power at the fuel pump module and the pump does not start then you have a bad Ground or the connection to the pump in the module is bad ,so ground the fuel pump black wire and switch on the ignition still nothing then remove the fuel pum module and check the connection to the fuel pump in the module .

If you have power then the org / red wire is good the problem is the pump connections ground .

Greg.

Customer: replied 2 months ago.
Ok, what's the best way to ground it?
Expert:  Greg replied 2 months ago.

Like said above Michael .

Connect a jump lead from the fuel pump black wire and ground it .

If this side is the problem its should activate the pump.

Greg

Customer: replied 2 months ago.
That did not work either.
Expert:  Greg replied 2 months ago.

Okay Michael something gone wrong with whats being done .

If you have battery power to the fuel pump with the Orange and red wire the pump should work if you connect a good ground.

How did you test the fuel pump to see if it worked .

Drop the tank keep the electrical connector connected and switch on the ignition check at the org/red wire you have battery voltage.

If voltage and no pump activation remove and inspect the connections on the fuel pump .

If you have voltage up to the pump connection then it should work with a good ground .otherwise bad connection from the connector to the fuel pump in the module ..

Customer: replied 2 months ago.
My father in law with over 30 years of experience as a mechanic was working with me on this all day yesterday. He's completely stumped which is the only reason I tried this to see if there's something electronic that could be wrong, because the newer computer electronics are out of his experience.We tested the pump but applying power directly from the batter to the terminals on the pump module.The pump is receiving 10.3 volts.
Expert:  Greg replied 2 months ago.

okay good but lets see if we do have battery power at the fuel pump when ignition switched on .is the tank still loose or fitted .

if fitted you will have to drop it again to gain access to the connector .

Dad in law may also have a fuel pressure gauge that you can hook up to the fuel rail.

If you have a good scan tool you can activate the fuel pump to test the circuits and fuel pressure .

when activating the fuel pump and nothing happens then the connection at the fuel pump or inside the module is the problem .

Greg

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