Fuel Sender wiring

[TMcG]

Greetings, new to the forum, isn't the internet great !  :)

Have done a search but couldn't quite get the specifics so;

Have a 2003 Aquasport Osprey 20' CC (2000 ?) and the fuel gauge has stopped working, sure enough there is a broken wire on the sender, the pink one.

The sender itself has a screw/post sticking up in the center, is that what the pink wire is (or should be) attached to ?

There is also a lot of chalky debris around the sender and tank top in general, is that just accumulated dust and bilge gunk or is there some coating thats broken down on the top of the coffin/tank area ?

Thanks in advance
tony

[RickK]

Welcome aboard Tony  :!:  :!:

[flounderpounder225]

Tony
The whiteish stuff is corrosion, there will be a gasket under the screw down base of the sending unit going into the tank.  DISCONNECT YOUR BATTERY/BATTERIES.  Just had a friend about a month ago go to the burn unit after a spark ignited the fumes in his bilge area while re-connecting this wire, could have been a static dis-charge, but don't take any chances.  Take a small wire brush and clean around the sender, with some WD-40 or something like that, so that you can see the condition of the base plate and screws.  The pink wire goes to the post on the sending unit like you thought.  Also somewhere near the sending unit there should be a welded on tab with a black wire connected to it, this is your ground for the tank.  The way a sending unit works is; on the gage in your dash there is 12 VDC coming in on the positive side of the meter, the other side goes to your fuel sending unit (the pink wire) the gage is searching for a ground, which it accomplishes as the circuit goes through the sending unit's float which is basically a resistor, as the fuel level rises and falls so does the resistance and the reading on your dash gage.  More than likely it is just corrosion and bad connections.  Do you have and do you know how to use a volt Ohm Meter?  If so, check for 12VDC on the positive side of the gas gage in your dash, if you have 12VDC, check the ground side of the gage using the Ohm function of the meter, you can check the Gage itself by applying a ground to the "ground side of the gage and you should see it deflect all the way one way or the other.  If you want to remove the sending unit from the tank, take care in removing the screws, strip one, and its a PITA to repair, use a good Phillips screwdriver #2 tip.  You can test the sending unit by putting one of the leads of the ohm meter on the center post, and the other attached to the base of the sender and slowly move the float up and down, the meter should change readings as you do this.  Good luck
Marc

[TMcG]

Thanks Rick.

Marc, wow !.  Much appreciated, EXACTLY what I was hoping for.

I am very familiar with Ohm meters and now I have the info to do it rather than guess at it.

Thanks again, will be sure to take that advice on the battery terminals.

[flounderpounder225]

Tony
How did it work out?? Just wondering
Marc

[TMcG]

Marc, too much work, not enough play I'm afraid, haven't had a chance to get down to the marina and fix it yet.

Will let you know though.

tony

[TMcG]

So, update, finally !

Got the opportunity to re-attach the sender wire today but like a complete goob, left the multimeter at home, sheesh !

All the gunk around the top of the tank was just that, gunk and cleaned off ok with a bit of elbow grease and appropriate cleaning materials.

The unfortunate end result though, despite now having good connectivity is that the gauge still doesn't read.  It starts to head north and then pauses and goes back to the stop, bummer !

The interesting thing is that there is an "extra" ground post on the sender and when I hold the pink (now red) wire against that the gauge goes all the way to max stop, what would that imply ?

[seabob4]

Tony,
When you hold the sender lead against the ground and the fuel gauge pegs to full, that says your gauge is working properly.  Have you pulled the sender yet and excercised the float while observing the gauge?

[TMcG]

Thanks SB,

So I guess that means the gauge is working fine then.

Haven't pulled the sender yet, was hoping it was just the wire, guess not.

Don't suppose you recall who supplied the sender units do you ?

[seabob4]

Tony,
If it's a swing arm type float, it's probably a Moeller unit.  If it's a solid state unit that has a float that rides up and down on a shaft, it would probably be a WEMA.  Can't tell 'til we see... 8)

[cdoyal]

As some of you know, I bought a 245 Explorer that had some oxidation "issues". The tach, trim/tilt, and one pump worked when I bought it and that's it. I rewired the entire thing  with new gauges, pumps, lights, etc. and now everything works except for the fuel gauge at the helm. For the life of me, I couldn't break the five screws loose that hold down the sender. It's a cool one with an analog gauge right on the tank so I didn't want to replace it if I didn't need to. Several days of soaking it in PB Blaster didn't even break them free. I went to Sears and bought one of those drill bit sets that extracts stripped screws and got ready to to dive in. But then I remembered someone here posting the need for a brand new #2 screw bit when doing this. So I put a new one on my gun and damn it if every one backed out slick as snot. I replaced the screws and gasket with new ones after putting the sender on a meter and it checked out fine. Turns out I forgot to hook up the ground so now everything works and I'm a happy boy - all thanks to this forum. Woo Hoo!!!  

[seabob4]

YAAAHHHOOO!!!

[John Jones]

None of us have ever made a mistake like leaving off a ground wire.

       

Actually, most just don't admit it.

I know, smack me.  

Glad you got it working.

[TMcG]

Oh how I wish it were that easy !

Will take that tip about the bright shiny new #2 bit though.