Fuel Gauge/Sending Unit Problems

[devildg4671]

I have a 2005 Sea Pro 206cc that I recently filled up and changed out a battery. Soon after I noticed that my feul gauge wasn't working and was reading below empty. I used a jumper wire to test my gauge, which read full during the test, then shot back over to empty. I bought a new sending unit from West Marine, installed it and still noticed the fuel gauge wasn't working. The new style is a Moeller universal sending unit, which was fairly easy to install, the one I pulled our was a reed sending unit. I've tried switching both wires (red and Black) around on the unit with no luck of anything working.

I'm completely lost, but was thinking maybe there's a ground or wiring issue. Which I have no idea where to start looking.


If anyone has any suggestions I would love to hear them.

 

[reddogg]

Re: Fuel Gauge/Sending Unit Problems

Is it grounded? Do you have the 12v power from the key switch running to the gage? Could the gage be bad? Loose connections?

red

 

[devildg4671]

Re: Fuel Gauge/Sending Unit Problems

All the wires to the guage are in the same place they were the other day when it worked fine. Could this be a wiring problem from the gauge to the sending unit ?

 

[reddogg]

Re: Fuel Gauge/Sending Unit Problems

Could be. There is a ground and a hot wire running from the sending unit to the gage. Make sure the unit is grounded. Power for the gage comes from the 12v supply from the keyswitch, should be the same supply wire powering your other gages. Check to make sure all connections are tight and clean, also check to see if there are any extra fuses inline that may have blown when you jumped it to test it. As long as it's grounded properly and you have the 12v keyswitch power hooked up it should work unless you have a bad gage or you hooked the wires up wrong.

red

 

[devildg4671]

Re: Fuel Gauge/Sending Unit Problems

All of the wiring and grounds look great in the center console. I was wondering if anyone has any idea of what might be tied into the wires leading from the sending unit ? About a foot forward of the sending unit it seems there's a few wires that have been spliced in, but they are in a location to where I can't see them and I can't seem to pull them to take a peek..
Anymore suggestions before I pull it over to the mechanic

 

[reddogg]

Re: Fuel Gauge/Sending Unit Problems

hmm, i can't think of any reason something would be spliced into the wires off the sending unit. If the unit is grounded, the gage is grounded and power is supplied via the 12v power wire from the key switch, it should work. If the wiring is good and connected properly than either the unit or the gage is bad. Can't think of anything else it could be uless there is a blown fuse somewhere. Well, that's my best guess.

red

 

[Silvertip]

Re: Fuel Gauge/Sending Unit Problems

The problem is not at the gauge since you proved it is working by jumping the "S" terminal to ground. Next you need to disconnect the wire on the "S" terminal at the gauge and measure the resistance to ground. Depending on how much fuel there is in the tank would produce a reading of 33 ohms (full tank), 109 (1/2 tank) and 240 ohms (empty tank). Anything in between you can figure out yourself. Numbers are not absolute but should be reasonably close. If this test shows open circuit, then either the wire between the gauge and sender is bad or the metal shell of the sender is not grounded. There should be only two wires on the sender. The one going to the gauge and the ground wire. If the sender is not grounded the system will not work.