Fuel gauge issue after pump install

Inspectorrobb · **Joined:** Tue Oct 15, 2019 11:12 am **Posts:** 15

So last weekend finally got the fuel pump and wiring harness, that I got from Sasquatch, into the tank. Swapped the float arm, followed the Git it Garage video, updated the lines, plugged everything in and starts up great.

Problem is, the fuel gauge is sketchy. I turn the key on, Gauge goes right up like it should. I start the jeep, the gauge goes to empty and light comes on. While driving, it will start to come up to where it should be, and then stays there, but then sometimes just randomly will go back to empty.

I wasn't sure if cutting the notch was a major deal, and actually forgot and just mounted the pump, so it may not be exactly centered, but if anything it's only twisted a little bit. But if it was hitting something I would imagine it would stay the same, not randomly work, and not work, especially when it works totally fine with the key on but not started.

Any hints on where to start before I tear this thing apart again?

Thanks,

WWDiesel · **Posted:** Fri Jun 03, 2022 11:08 pm

Based on your description, you could have a bad connection or bad sending unit inside the fuel tank?
Is is an 05 or 06?

Check the connector under the rear seat and make sure all of the pins are making a good connection at all times, none are loose.
The connector on top of the fuel tank could also possibly have a loose or bad connection.
If all the connections are proven to be good and secure, guess you will have to fully drop the tank and pull the tank unit out and check float movement.

Once you have the tank unit out, you can connect an ohmmeter to the pins for the gauge sending unit and manually stroke the float lever up and down and see what the ohms are doing.
It could possibly be a bad rheostat on the tank unit.

This is the wiring schematic for the 05 model.
2005 Model Intank fuel pump retrofit wiring:

Inspectorrobb · **Joined:** Tue Oct 15, 2019 11:12 am **Posts:** 15

Thanks, I'll go through the connections today. And it's an 06. Wasn't sure if the Brain box was going to be all screwy for a minute since it's got a pump now. We'll get it figured out. It does run really good.

You think when you replace stuff with all brand new, it's not gonna have any problems, and then you get something like this.

I have a Ford 4000 tractor, redid all the wires, points, distributor, blah blah... no spark... played with it for a week scratching my head and here it just ended up being the brand new expensive coil wire was open. Put a new one on and bam, fired right up. Good Times!

WWDiesel · **Posted:** Sat Jun 04, 2022 2:48 pm

Inspectorrobb wrote:

Thanks, I'll go through the connections today. And it's an 06. Wasn't sure if the Brain box was going to be all screwy for a minute since it's got a pump now. We'll get it figured out. It does run really good.

You think when you replace stuff with all brand new, it's not gonna have any problems, and then you get something like this.

I have a Ford 4000 tractor, redid all the wires, points, distributor, blah blah... no spark... played with it for a week scratching my head and here it just ended up being the brand new expensive coil wire was open. Put a new one on and bam, fired right up. Good Times!

Quote:

Years ago, I did a lot of work to a Honda car and after completion, it would not start! It was running when I drove it into the shop. I started replacing electrical parts with the old ones one at a time until it started. It was a bad condenser brand new out of box.
"NEW PARTS" can be defective. :banghead:

The major difference between the 05 & 06 models are, the fuel level sensor wires go to the Body Control Module (06's don't have a Front Control Module)
Wire colors for the level sensor are the same as an 05 model according to the FSM.

The big connector under the rear seat does have two more wires in it for the anti-lock brake sensors. See drawing:

2006 Model Intank fuel pump retrofit wiring:

Fuel gauge issue after pump install

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