Fuel Gauge Issue

[CrAzEd412]

Hello all,
First let me begin by expressing my gratitude that this website exists! It has saved me a lot of money and time trying to fix problems on my aging Explorer.

The problem that I am experiencing currently is my fuel gauge registering past full. I've searched countless times and spent many hours trying to find someone else who has had the same issue. The threads that I have been able to find helped at first but the problem still remains. I've already been through 3 fuel pumps (all Spectra Premiums from Autozone), the current fuel pump in my Explorer being a Spectra. I would love to put an OEM Motorcraft pump in the tank but cannot afford it at this time since I am still in college. This being my 3rd fuel pump I am at my wits end trying to figure out why the fuel gauge is giving a reading past full.

I recently replaced the fuel pump about 2 weeks ago while trying to fix the issue after I had replaced the instrument panel from a junkyard Explorer. Thankfully I was still under the 1yr warranty for the old pump as it had begun to make a very loud hum noise that could be heard outside and inside of the vehicle. Not only did it have the loud hum, the noise began to fluctuate and almost hesitate to run like it was on its way out. Long story short, dropped the tank replaced the pump with a new one thanks to the warranty (pissed I had to drop the tank again in less than a year to replace it). Before I put the new pump in I made sure it was giving the correct ohm reading by moving the float up and down, put the new one in and buttoned everything back up. Filled up the tank and the gauge was reading correctly, worked great for a few days but on my way home from work I noticed that it had begun to creep back up past full. I know I didn't have a full tank, at that point I had about 1/2 tank. The odd thing is if I let it sit overnight the needle sometimes drop down to the correct fuel level other times it won't and will stay past full.

Also have a problem with my Explorer shutting off randomly sometimes(while driving) or not even starting up after driving for a little while, this I narrowed down to the fuel pump relay (replaced 2 times). When it shuts off I pop the hood, pull out the relay and tap on it plug it back in and it starts right up as if nothing was wrong. I talked to a buddy of mine about the issues I'm having and he thinks I could have a possible ground short somewhere.

I apologize about the length of this post but like I said I am at my wits end as to what the problem is. Figured it would be easier for me to write up all that I have done in order to narrow it down and find a fix to my issues.

Thanks!
- Jeremy

 

[koda2000]

fuel gauge - did you replace just the fuel pump or the entire fuel pump assembly? the pump has nothing to do with the fuel gauge. so, assuming you replaced the entire assembly and you're having this issue:

the fuel gauge works by OMS resistance. usually, the more resistance, the higher the gauge reads. as your gauge is reading past FULL it is receiving maximum resistance. if this resistance isn't due to a problem with the fuel pump assembly, or the fuel gauge, about the only thing left is that the wire for the fuel gauge is grounded out somewhere. all you can do is check your wiring, find the bare spot and fix it.

note: depending on how the Ford fuel gauge works, it is possible the exact opposite may be the case. that is to say, the fuel gauge reading past FULL may be the result of a broken wire (open circuit) in which case you need to look for a bad connection or broken wire.

 

[CrAzEd412]

Oops! I completely forgot to mention that I replaced the entire assembly, good catch! I'll have to trace the wires from back to front to find anything broken or loose connection like you suggested.
Thanks for the reply!

 

[koda2000]

Oops! I completely forgot to mention that I replaced the entire assembly, good catch! I'll have to trace the wires from back to front to find anything broken or loose connection like you suggested.
Thanks for the reply!

you might find something useful here (free wiring diagrams). use rrcc and rebsco to log in. if you figure out which wire goes to the gauge you can try jumping it/replacing it. that might be easier that trying to find a break.

http://search.ebscohost.com/

 

[CrAzEd412]

Well its been months and I still haven't found the issue. During my troubleshooting I unplugged the wire harness at the pump and checked the resistance and its where its supposed to be, moved up the line and checked again and its where it should be. The only thing i can think is that it has to do something with the gauge cluster or the wiring to it. Ive already replaced my gauge cluster because my tach wasnt working at the time. I believe i read in another post that the wire im looking for is a yellow/white? If I find that the resistance is not correct once I check the plug at the instrument cluster what should I plan to look next or attempt to figure out another fix?