Issue with Fuel Gauge

[Mellow Yellow]

Had to move the Mustang today. The battery was dead, so I jump started it with a booster pack.

While the battery was charging I noticed the needle on the fuel gauge was pointing straight down. It normally sweeps left and right in the up position.
The needle moves when the power is turned off and on. I have checked the fuse.

Any thoughts about what might be wrong. Maybe the ground by the fuel tank is an issue?

Thanks in advance.


BTW the car is a 2005 3V GT

[ZR]

With the battery have been dead, possible it just needs to run / be driven long enough for the module to relearn to balance the signal from left / right level sensors. Also possible it's one or both senders acting up due to a build up of sulphur. GM's fuel system cleaner plus has Techron in it, many see the gauge return to normal after using a bottle or two. If your lucky enough to find it, Chevron's Fuel system cleaner also contains it and is usually much cheaper. GM stuff is just rebranded Chevron (bottom of the gm bottle has Chevron emblem).

In the future, always safer to at least partially charge a dead battery vs boosting from absolutely flat. Had a similar issue with my Cobra, when boosted, shot speedo needle up and over it's stop. Had to remove / pull cluster apart to repair. Not a supper common issue but can happen.

[KIDAGIN]

A few weeks ago I left the interior light on in my DD and killed the battery. I boosted it to get going. Then a couple of days later I noticed the passanger window didn't work. Today I searched the internet a found a minute procedure to reset and reprogram the windows. Problem solved.
Some strange things can happen when the battery is removed or dies.

[ZR]

Pretty odd isn't it Doug.

[KIDAGIN]

Yep had me wonerding for a bit

[ZR]

Good on ya for figuring it out.

[KIDAGIN]

Was happy for the easy solution

[Ponyryd]

As stated often times boasting a battery can do stupid stuff to the electronics. You may need to remove the cluster and re-time the guage. I've often had clusters out for this same issue, usually turn them upside down, and lightly tap them to reseat the needle in question.
Do you know how much fuel was in it? Smart guy like you would likely have the tank full for winter storage, so you could try burning some of that fuel off, and filling at afterwards, the needle may return to its proper position.

[Mellow Yellow]

As stated often times boasting a battery can do stupid stuff to the electronics. You may need to remove the cluster and re-time the guage. I've often had clusters out for this same issue, usually turn them upside down, and lightly tap them to reseat the needle in question.
Do you know how much fuel was in it? Smart guy like you would likely have the tank full for winter storage, so you could try burning some of that fuel off, and filling at afterwards, the needle may return to its proper position.


Thanks for the compliment! LOL

But yeah the tank is full. I won't be driving it for another month or so.

BTW I was moving the mustang as I've sold my 280zx, the one with the low miles. Guy is picking it up next weekend.

[Ponyryd]

The project, or the nice one?

[Mellow Yellow]

The project, or the nice one?

The nice one.

Going to use some of the money to get the metal work done on the project.

Know anyone that is good at taking unibody cars apart and welding them back together?
The one I was going to use has closed up.

[NickD]

full electronic gauges, you confirmed it moves with power so its prob not the servo motor, if it was fine before it would seem odd that the fuel level sender would be bad?
I have heard and experienced our cars doing some weird things when its cold, Ive had issues, turn it off then on again and it goes away, other times reflashing your tune can solve problems (I had weird idle and seemed to be running off, reflash and bam-I blame it on crappy bama tunes)
I wouldn't worry until you take it out in the spring

[Ponyryd]

Know anyone that is good at taking unibody cars apart and welding them back together?
The one I was going to use has closed up.

No, can't say that I do. I'll ask around.

[Mellow Yellow]

Well we found the issue. This also resulted in a drained battery while car was just sitting.

There is something called a smart junction box, located on the passenger side under the dash. Some connections were full of corrosion, causing a short.
The obvious question I now have is corrosion is caused by water......so where did it come from?

The gauge was not operating properly because of low voltage from the battery.

Why do I feel that I'm going to be the guinea pig here....as I have 255,000 kms on the car I'm sure I will run into problems sooner than most....hooray!

[ZR]

Smart junction box corroded is very common, Google search will bring up a bunch threads.
Best to track down and repair the water leak before replacing.

[ZR]

Recent thread on the same issue here.

http://www.torontomustangclub.ca/forums/showthread.php?4123-Dash-lights-staying-on&highlight=water+leak

[Screw]

I experienced same problem with water at the sjb , I let dealer do their tsb , cowl plugs , pinch seams , they did not do the gaskets over the windows .

[ZR]

Was there any resistance at the dealers end due to TSB being so old?

[Screw]

No resistance just pay the fkrs they're happy

[ZR]

LOL

[Mellow Yellow]

Recent thread on the same issue here.

http://www.torontomustangclub.ca/forums/showthread.php?4123-Dash-lights-staying-on&highlight=water+leak

WOW!

Looks like this may not be an isolated problem. Will now ensure those drains are cleared.

[ZR]

Several spots that are prone to letting water in.