P0463 code wont go away

Backstory: Bought this 2006 Jeep Unlimited recently and previous owner said he drove with check engine light on for over 2 years. Fuel level gauge didn't work unless tank was almost completely full. Ran the codes before buying and got: P0463 - Fuel level sensor 1 circuit high, P0421 warm up catalyst 1/1 efficiency, P0032 O2 sensor 1/1 heater circuit high, and P0052 O2 sensor 2/1 heater circuit high.

Fast forward to now: Checked both O2 sensors on bank 1. Primary O2 sensor had a dent in it so replaced it, secondary sensor was ok so left it alone. Dropped the tank and replaced the fuel pump assembly with a "Delphi FG0924 Fuel Module". Fuel level gauge now works fine.

Check engine light went away immediately after replacing fuel pump assembly. Ran some errands with it, turned jeep on and off multiple times...all good. Then randomly check engine light came back on after starting the jeep. Same 4 codes as before....I've cleared the codes twice now and both times the check engine light stays off for about a day and then will randomly come back with the same codes. Fuel level gauge working as it should the whole time.

Does anyone know what could be causing these codes to keep coming back? I've checked wiring and connectors and haven't found anything. I did notice the contact patch for the float looked to be burned up on the old pump assembly, see attached pictures.

Thanks for the input guys! The grounding strap that leads to the firewall is secured on top of the cylinder head near the back of the valve cover, drivers side. Is this the correct location for the strap? It's covered in oil, going to need to replace valve cover gasket. There's another ground wire on the passenger side connected to the block but it connects to the battery if I remember correctly, forgot to take a picture of that one.

I drove the jeep around a bunch last night checking codes and clearing them as they appeared. After the third time clearing the codes (since replacing fuel pump) the P0463 hasn't come back. So to anyone in the future looking for a resolution, my P0463 went away after the third check engine light after replacing fuel pump assembly and clearing the codes.

Still getting the other 3 though, maybe catalytic converter on bank 1 is toast? I was planning to do oil pan gasket and rear main seal so I will probably order one of the Walker mid pipe replacements and throw that on when doing the seals.

May look into deleting the cats all together depending on how much $ this all comes out to. No emissions testing in Florida. Battery is dated 08/22 so no issue there.

Figured I'd update this thread...got around to removing the exhaust, one of the smaller catalytic converters disintegrated. Replaced all 3 cats with a flowmaster kit I found on amazon. Check engine light has stayed off since, been three days now.

Flowmaster kit is good for the price, the smaller cats are larger than the OEM ones so you will need to get creative to tighten the bolts. Wasn't able to fit a swivel socket on the middle two bolts like I could removing them. I had a buddy hold a wrench on the top nut while I reached up high with another wrench from the bottom. Pics of old exhaust

Well I'm back...fuel level sensor has failed again on the new pump assembly.

How it happened: I was out on a trail, it was raining, went through some deep ruts with water in them. They were deeper than I thought, should've gone slower...but jeep made it out fine. Immediately after getting out of the ruts, not even 10 feet, jeep begins to stutter and dies. Fuel pump fuse was blown. Swap fuse and drive home avoiding all water. Pump works fine but the next day the gas gauge stopped working and hasn't come back.

I call a mechanic friend who's worked on a few 4.0L engines and he tells me the pump is bad and that the same thing would've happened if I was just driving on the road. I trust this friend, but the timing of the failure didn't feel like a coincidence.

What do you guys think? Is there potential I have more going on here than getting a faulty pump? The reason I replaced the old pump was because the level sending unit had failed, when i got it out, the contact patch for the sensor was fried.

macleanflood said:

Everything is possible.

I'd get out the FSM and look at the wiring diagrams and check the resistance values on the wire coming out of the pump, maybe add gas or drive it a bit and see how that value changes.

What manufacturers pump did you install? Not all are equal.

When you installed it did you check the inside of the tank?

I put in a Brute Power...about the cheapest one on Rock Auto. The fuel level is a little off...I'd prefer the fuel light to come on a little lower in the tank.

It survived knocking down the Rubicon. Fuel pressure dropped to 30 a couple of times. Guessing the gas was getting sloshed and aereated. And once after a hard knock on the tank the fuel level dropped to empty and I figured it was done...bounced a few more times off rocks and it was right back in the game.

-Mac

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Measuring the resistance before and after adding fuel is a good idea, maybe something is going on in the cluster. The car did scrape pretty hard on the skid plate, definitely had an impact force lol I'll try whacking the bottom of the tank with a 2x4 a few times and see if that does anything to bring the fuel level back

I installed a Delphi FG0924. Yeah I took a look in the tank, inside it was in good shape.

JKP said:

Last time I checked you can still get the OEM Bosch fuel pump from Rock Auto or off Amazon.

I picked one up as a spare.

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The pump itself is still available, the OEM assembly is not. I'm going through the process of getting a replacement pump assembly through warranty so regardless I'll be dropping the tank again.

For now I just drive around with a few spare fuses in case it happens again...

Back again for an update....

Dopped the fuel tank a second time, warrantied the first pump assembly, got a new one and installed it. Gas gauge still doesn't work, but pump itself is fine. Go to gas station to fill up and gas wont go in the tank, do some research and found out the valve in the filler neck has some tolerance issues. Fast forward some time and I drop the tank a third time, sand down the tabs on the valve for filler neck...can now pump gas in like normal, sweet.

This third time the tank was out i made sure to check everything I could. The resistance on the float switch checked out ranging from 20-220 ohms on both old and new pumps. Connector looked good on both ends, no loose wires. Followed the wires to the transfer case, nothing unusual there. Tested the gauge cluster, gas gauge works. Replaced the valve cover gasket and cleaned off the grounding strap on the head stud. This stopped the slow oil leak but did nothing from an electrical point of view (at least from what I can tell).

I'm planning to open up the harness and trace it back as far as I can with the hope one or both of the wires responsible for fuel level are damaged. Is there a way to test the fuel level signal without cutting wires and measuring the resistance?

What would you guys do next? The jeep drives fine I just want these stupid gauge lights to turn off!

Searched around the 2006 Service manual for the wiring. My plan is test the resistance at the PCM connectors, if wiring is good it should come back within the range of 20-220 ohms. I'm hoping the resistance comes back very high, indicating there's a problem in the wiring. Rather than tracing it down I'll run new wires. Gotta wait for my other car to be driving again before I dive into this...based on how this jeep has acted so far once I unplug those connectors I'll have more issues lol

Found the issue. Rear bump stops were shot and this allowed the rear axle to travel up high enough to where the track bar mount on the axle must have done the damage. One wire was cut, another wasn't far behind. Just dumb luck the two pump wires weren't affected. The vapor line was also cut in half.