Fuel Gage M939 not reading

[tubamlb]

Fuel Gage shows Emty , when I pull sending wire from transfer switch it shows Full ?

 

[pjwest03]

Typically, the military fuel gauges read empty when grounded and full scale when the input is open. Possibly the circuit is shorted to ground somewhere or there is an issue at the sender.

 

[98G]

Your float has become a sink...

 

[pjwest03]

Your float has become a sink...

Frequently the case.

 

[Coffey1]

Yes its a brass float and it gets pinholes then fills with fuel.
You can get a plastic one that is a perfect match from summit racing.

 

[Gunzy]

You can get a stick for free then just dip the tank from time to time. Plus, it will be more accurate that any MV fuel gauge in history. Just sayin'.

 

[Coffey1]

Gunzy mine work pretty darn good once I changed that heavy brass float full of fuel.

 

[tubamlb]

Hi
Were you able to change the float through the fuel opening or did you need to pull the tank

Thank you

 

[Coffey1]

Just pull the sending unit.

 

[tubamlb]

I have a wrecker so there is not any space to pull the sending unit , that is why I asked if there was any other way to rep the floats

 

[Coffey1]

Nope I guess tank dropping time.

 

[tubamlb]

Hi
Any idea how to get to the fuel lines so I can drop the tank

Thank you

 

[simp5782]

Hi
Any idea how to get to the fuel lines so I can drop the tank

Thank you

On a wrecker? Remove the outrigger. You just have to move the wrench a little at a time to get them off. You can pull the straps and move the tank out towards you some for a little easier access as they will give

 

[gstirling]

tank sender

i have a m936 and you have to pull the tanks and work around the out rigger, just pull the out rigger out, about half way if i remember right, then you can slide the tank out a bit and back around the out rigger. the sender is located on the frame side of the tank, so have to pull the tank pretty far out. the emptier the tank the easier it is (obviously). soak all the fuel connections and various bolts with penetrating oil the day before you try it. is a good time to see how clean the tank is and wipe out any "stuff" in the bottom. last thing you will have to unbolt the grounding straps(wire) from the tank to the frame - clean it up really -- really good. as this could your issue to begin with. so hey maybe check that first!!!
note i think i had to rig up some temporary supports for the tank as i slide it out, boards between the normal supports or a saw horse, something along that line.

Like Simp said, little movements to unscrew the fuel lines, also a crow's foot is a big help, will speed it up a lot.

 

[simp5782]

i have a m936 and you have to pull the tanks and work around the out rigger, just pull the out rigger out, about half way if i remember right, then you can slide the tank out a bit and back around the out rigger. the sender is located on the frame side of the tank, so have to pull the tank pretty far out. the emptier the tank the easier it is (obviously). soak all the fuel connections and various bolts with penetrating oil the day before you try it. is a good time to see how clean the tank is and wipe out any "stuff" in the bottom. last thing you will have to unbolt the grounding straps(wire) from the tank to the frame - clean it up really -- really good. as this could your issue to begin with. so hey maybe check that first!!!
note i think i had to rig up some temporary supports for the tank as i slide it out, boards between the normal supports or a saw horse, something along that line.

The inside of the outrigger just has a pin that goes into the pivot point. You just remove it out of that so you dont have to work around it and simply set it to the side. I do this when i want to move around back and forth a good bit in the truck and need the outriggers so i just move them around by hand and re pin them rather than having to pivot them back up and spin am and all that junk.

the M1089 FMTV wrecker hydraulic outriggers are a life saver.

 

[gstirling]

The inside of the outrigger just has a pin that goes into the pivot point. You just remove it out of that so you dont have to work around it and simply set it to the side. I do this when i want to move around back and forth a good bit in the truck and need the outriggers so i just move them around by hand and re pin them rather than having to pivot them back up and spin am and all that junk.

the M1089 FMTV wrecker hydraulic outriggers are a life saver.

work smart not hard... good point. those things are heavy.