New fuel gauge only reads 1/2 tank?????

[MI_Thumb_2010]

I have installed a new fuel gauge,sender,and wiring but my gauge will only read 1/2 tank at all times.I wired everything according to the diagram i found on this site.Any ideas what the problem could be?Do i have the wrong type of sender for my gauge?Is that even possible?

1976 21' Thompson "Fisherman" 302 I/O w/Volvo 280 outdrive

 

[Pez Vela]

Re: New fuel gauge only reads 1/2 tank?????

Remove the sender from the tank and reconnect it to the gauge/ground connections. Move the sender's articulating mechanism through its full range of motion while monitoring the readings on the gauge. If it performs as expected, the sender may have been installed in an improper orientation, so that the articulating mechanism is stuck or otherwise restricted in movement by the fuel tank. If the gauge does not perform as expected outside of the tank, then it's either wired incorrectly or there's a defective part.

 

[MI_Thumb_2010]

Re: New fuel gauge only reads 1/2 tank?????

Guess i'll have to give that a try but its a whole lot of work to pull the tank in my boat to get the sender out.Could it be a bad ground,or would i get any reading at all with a bad ground?

 

[Pez Vela]

Re: New fuel gauge only reads 1/2 tank?????

Wow ... I didn't think you'd have to pull the tank to access the sending unit. A bad ground was my problem, so yes, that could definitely be the source of yours as well. Yes, you may get a reading with a bad ground (I did) but it was way off what I knew to be a full tank. Let us know if correcting the ground solves it.

 

[MI_Thumb_2010]

Re: New fuel gauge only reads 1/2 tank?????

I will be headed over there on Monday to check it out(Boat is docked)I'll post after that.Thanks

 

[MI_Thumb_2010]

Re: New fuel gauge only reads 1/2 tank?????

1 more thing just so i know i'm doing it right.The ground tab on the top of the sending unit goes to a ground on the motor block or neg terminal on battery and not to the ground on the gauge..correct???

 

[Pez Vela]

Re: New fuel gauge only reads 1/2 tank?????

That's how mine works.

 

[Silvertip]

Re: New fuel gauge only reads 1/2 tank?????

A bad ground (as in no ground) means the gauge will not work at all. High resistance in the connections will make it read zero. The float arm is usually adjustable and the sender itself may require adjustment for tank depth. By adjustment I mean being physically cut off. If you know how to measure resistance of the sender, 240 ohms = empty. 109 ohms = half full and 33 ohms = full. All numbers are give or take a little. Make sure the float arm is not binding on the side of the tank. The float arm can be bent to make it more accurate but keep in mind you want it accurate at EMPTY. You know when the tank is full but you don't know when it is empty even if the gauge says empty so that's where you want to verify calibration. Also be aware that if adjust the low end you compromise the high end and vice versa.