Fuel Gauge Question

[Jim and Jutta]

The 71 is in storage for the winter, after sitting for a month started it up just to lube everything up. Started right up but noticed the fuel gauge indicates empty (din't move) , although tank is full. Fuel gauge worked when put in the garage for winter storage. All other gauges working fine.

Any suggestions?

Jim

 

[adm22]

Could be a bad fuel gague sending unit. You can get a replacement or the float is bad. They made generic ones to replace these, they can geet a hole in them that cuases them to fill up with petrol and sink thus reading empty.

 

[don29163]

if you unplug the wire at the tank and jumper across the 2 female connectors ....turn on key...should go to full. If it does, the trouble is the tank unit, or float.

 

[Totalled]

1. Float sunk.

2. Ethanol gas corroded the rheostat in the sender.

3. Other.

 

[caspianwendell]

could just be a bad ground

 

[Wolverine]

if you unplug the wire at the tank and jumper across the 2 female connectors ....turn on key...should go to full. If it does, the trouble is the tank unit, or float.

Step #1...been through this. Float developed hole, sank. Should have kept it for the White Elephant exchange...

 

[c9zx]

Don29163's post is spot on. Do as he suggested. Just don't leave the key on and the jumper in place for a long time as 0 ohms is outside the resistance value for the circuit. Chuck

 

[Jim and Jutta]

if you unplug the wire at the tank and jumper across the 2 female connectors ....turn on key...should go to full. If it does, the trouble is the tank unit, or float.

Thanks Don, sounds like a good starting point to pin point where the issue is. So where are the two female connectors and wire located, under the car on the tank, trunk?

Jim

 

[marks73]

They are on the plug on the DS of the tank at the middle

 

[Wolverine]

They are on the plug on the DS of the tank at the middle

Don't forget you have 18 gallons of gasoline behind the plug you are pulling. You should be okay, but 18 gallons of gas can do a lot of damage to your car, not to mention the environment.

Little known fact- in the 1800's +/- 30 years, the only use for oil was to make kerosene. After processing the oil for kerosene, they dumped the reminder(basically gasoline) into rivers/streams/etc. because they didn't know what else to do with this volatile liquid. It wasn't unusual for someone to throw a lit cigarette into the river/stream and ignite it. Then, God invented the EPA. Well, not God. Nixon. Close enough.

 

[Go Time]

do you have a teenage son.... he may have siphoned out all the gas to go to the movies with his buddies, just a thought

 

[midlife]

if you unplug the wire at the tank and jumper across the 2 female connectors ....turn on key...should go to full. If it does, the trouble is the tank unit, or float.

I thought there was only one wire going to the fuel sending unit: the ground is via the tank to the chassis.

 

[Wolverine]

if you unplug the wire at the tank and jumper across the 2 female connectors ....turn on key...should go to full. If it does, the trouble is the tank unit, or float.

I thought there was only one wire going to the fuel sending unit: the ground is via the tank to the chassis.

You are not really grounding the connections...you are providing 0 resistance across the contacts, which is indicative of a full tank of gas.

 

[midlife]

Yeah, but there is only one wire or plug at the sending unit connector...

 

[marks73]

2 wire plug

 

[midlife]

My bad...I was thinking of all Mustangs prior to 71. Yup...a ground and fuel line wire. There's a two prong plug that mates to those two.

 

[Wolverine]

2 wire plug

What took you so long to respond to the 1 wire post? A whole minute?

 

[marks73]

2 wire plug

What took you so long to respond to the 1 wire post? A whole minute?

Had to go out and drop the tank

 

[Jim and Jutta]

I found the problem. Went to do the test Don recommended and found that the connecter had came loose. Plugged it in an it works fine, not sure how it came unplugged while parked in the garage but that was the issue.