For the last 3 weeks I have been having a strange problem with my truck and I will try to explain it in detail.

3 weeks ago I filled up my tank at night, It was 3/4's full and I just topped it off. I made sure to park the truck, AND remove the key. Gas was cheap at the station I went to so I made sure to fill it to the very top. From the gas station I went to the store to buy some groceries. The next day on my way to work about 3 miles into my trip all of a sudden my fuel gauge went from over F to below E instantly. The yellow "low fuel" light came on. Instantly, I said "what the hell I just filled it", but I pulled over and parked the truck to see if the tank was leaking. I looked underneath, and it was not - there was no sign of damage or spilled fuel. I then determined that the gauge must be reading incorrectly. I started the truck, and about a half mile down the road all of a sudden it jumped back up to full instantly, so I figured the problem was a fluke.

The tank worked properly for that full tank of gas as it was remaining. Last night I filled up again (filling the tank very very full) Of course I turned off the truck and removed the key when filling up. I measured my mileage at 21.5 Mpg (V6-3.0L). The gauge worked fine upon fill up, showing a full tank. about 4 miles down the road on my way home however it suddenly dropped to E and the fuel light came on. I did not pull over knowing that it was reading incorrectly, however I drove about 1 mile or less and it corrected itself to show full somewhat instantly again.

Obviously, from this story you can tell it only happens when I just fill up the tank. The truck is a 2004 edge V6 3.0 RWD. It has 32,000 Miles on it. Has anyone experienced anything like this before? There is no warranty because it is past 3 years old.

 

I have an old Dodge that does the same thing if I try to cram in as much as I can.Now it's 3 clicks and I call it full.
Also remember if you over fill the tank,There is a hose going from the filler tube to the charcoal canister for the emissions that doesn't like to suck in raw fuel.It is only meant to pull off vapors from the tank.

 

I have read and heard that you should not try to fill the tank till it is in the filler neck. As OTRtech said it back flows the system.

OTOH, there may be something wrong with the fuel level sender in your tank. If you fill the tank till it clicks off and only hit the handle once and the gauge never does it again I would take that as a good sign to not overfill it.

Try it and see.

 

Another possibility if you get in much water or mud is the connector block directly under the drivers seat. Undo it and clean it and coat it with dielectric compound if it's corroded.

Some members have had all sorts of unrelated problems with various systems because of problems in that connector.

 

I doubt that the problem is Mud - I clean my truck religiously (hand wash) every 2 or 3 days. I admit I am overfilling the tank - Lately I have been doing this when I can find gas a few cents cheaper. I will try and stop when it clicks at me telling that its full.

 

Meticulous cleaning is irrelevant. It DOES rain and snow in Chicago.

John's talking about the electrical connector under the driver seat, visible from UNDER the truck. It has a tendancy to get water in it, causing a variety of electrical issues.

That should be the first place you inspect for the problem you described. The fuel float uses a variable resistance potentiometer to display fuel level. If that signal gets compromised, your guage gets funky. The Full signal is 145 ohms, Empty is 22 ohms.

That should JUMP out at you to suspect a SHORT (a short to ground is < 22 ohms) in the fuel guage wiring, with the most likely spot being water in the connector under the seat. You should also inspect for a chafed wire touching metal between the tank and that connector.

The second place you should check is the connection on top of the fuel tank. Hard to fathom water collecting up there. Your choice where to start. Removing the bed makes access to the top of the tank easy. I did not say removing the bed is easy.

 

Isnt it fishy thought that it only happens a few miles after I fill up? you would guess that if it was harness related it would happen at random times.

 

Let's see, gas weighs what, 6.2 lbs. per gallon?

So, you have 120 lbs in a plastic tank, it flexes some (have you looked at the mounting straps? maybe one broke and your tank is hanging, stretching the harness into rubbing the bed or frame), and suddenly your gage gets a <22 ohms signal that comes and goes, but only when Full of gas. I'd be under there shaking the harness when it is showing Empty, to see if I could make it go back to Full.

That would be after I cleaned and applied dielectric grease to the aforementioned connector under the seat, however.

We only mention that connector because it is KNOWN to cause electrical problems.

In any case, you are looking for a short to ground. I'd look really hard before I decided to pull the bed off.


Please let us know what fixes your problem!!!!

 

the Ford taurus and a few others have the same problem and it is caused by the sending unit going bad and will throw a check engine light/code dealing with gauge not reading right. The cure is to replace the sending unit or just keeping a good idea of how far you have gone. I know this due to the fact my mother-n-law has the same issue but way worse on her taurus. Hers will not even tell the correct about in the tank more than a few miles at a time no matter what level is in there.

 

If I am in 4wd and I stall my truck the fuel gauge will go all the way to empty and then pop back up to full after I shut it off and then start it again

 

JP7, i hvae the same problem on my 94. yesterday as i was jockeyin my 5x10 trtailer around the yard the gauge was working just fine. today i got to run some errands and the damn fuel gauge is dead.

one poster mentioned a plug conection under the truck drivers seat area. id asume its in the harness running along the left frame rail correct?

the entire fuel pump sender asembly was replaced 6 monthes ago. some idiot tryed to suck fuel......untill he lost hit 10' chunk of hose in my tank. needless to say it broke my sender.

anyways i know the sender is brand frekin new i guess time to chase a electrical gremlin. i hate them bastards!

lol sorry thread hijack.

 

I filled up the tank without overfilling it twice since my last post. The first time I did not have this problem, but this morning after filling up my tank it cut out twice on the highway. I think my potentiometer is bad.