Gas gauge not working

[BigSexyPhoenix]

Gas gauge seems to be stuck on empty in my new bird. I've put 18 gallons of fuel in so far. When I first turn the key on the needle will jump just barely and return to empty. Where do I need to look first to troubleshoot?

[CatFan]

You'll have 3 or 4 leads on your gauge and 2 on your sending unit.

The sending unit has leads that should be labeled S and G for "Sending Unit" and "Ground" The ground should be black and the S might be pink.

The gauge wires will be labeled S, I, G and maybe L. S and G are the same as the sending unit. I is the 12V from the ignition, and L is 12V from the lighting circuit for the bulb in the gauge if it has one.

The first step is to verify that you have 12V between I and G on the back of your gauge when the key is on. If you don't, you have a problem outside the gauge/sender.

If you have the 12V between I and G, then short the S lead at the tank to the G lead. Your gauge will go to full if it is good. If the gauge tests good, connect the voltmeter from S to G on the gauge or at the tank and move the sending unit. You should see voltage ranging from 0-8V or 0-12V as you move it.

If you have 12V at the gauge, the gauge pegs when you short the leads and you don't get any voltage change when moving the sending unit, you most likely have a bad sending unit.

[liv4bassin]

Also, you may have seen many posts here regarding the "inaccuracy" of the readings of our gas gauges. Though yours may be a different problem, most of us also experience this. When my gauge on my 619 gets to E, I have approx. 8-10 gallons still in the tank. These inaccurate readings seem to be caused by the L shape of the tank itself. Hopefully you have a Merc monitor or smartcraft gauge to use for gas usage, the gauge itself is useless. Still hard to believe that there is not some way of getting a good gauge reading, unless the $70k + models for 2017 have worked it out.

[DREWTICK]

need to take the green cover off the top of the plug and make sure all the wires are push forward

1.purple
2 black
3open
4 blue
5 pink this is fuel****
6open
7 brown and white
8blue and brown

[DREWTICK]

pink wire is going to sending unit,
check resistance between pink and black

[BigSexyPhoenix]

Thanks. I'm gonna take a look when I get back from camping. It'd gotta be something simple.

[EdDavisKY]

Brand new boat!....Take it back to the dealer and have them fix it.

[DREWTICK]

my sending unit was stuck at the bottom brand new, Tim sent me a new one right away, is was easier for me to fix myself and no down time, would have cost me 2 days work to go to dealer.

[Ray Co. Hank]

Also, you may have seen many posts here regarding the "inaccuracy" of the readings of our gas gauges. Though yours may be a different problem, most of us also experience this. When my gauge on my 619 gets to E, I have approx. 8-10 gallons still in the tank. These inaccurate readings seem to be caused by the L shape of the tank itself. Hopefully you have a Merc monitor or smartcraft gauge to use for gas usage, the gauge itself is useless. Still hard to believe that there is not some way of getting a good gauge reading, unless the $70k + models for 2017 have worked it out.

My 2010 618 read as you described. I was counting on a similar outcome during break in on my '16 919. Luckily I wasn't but a couple miles from the ramp and had a buddy on the water. E = empty on this boat.

[Srford280]

I'll double check my '17 618 next time I fill up but if I remember right, I put like 28 gallons in it and it was still above E. Which would be pretty close with a 34 gallon tank.

[fishin couillon]

Are the sending units the ones with swing arms or a float on a straight shaft?

[DREWTICK]

Are the sending units the ones with swing arms or a float on a straight shaft?

straight shaft with a ring around

[Hunna]

Float might be stuck or a bad sending unit.