fuel gauge & fuel tank earthing issues

[mr_plow]

hi guys, i recently got a universal fuel gauge kit for my 80 litre alluminum fuel tank. ive installed it and it seems to work sometimes and not some other.
i am thinking it is a bad earth to the tank making the sensor not work, as i have used the fuel gauges earth and run a 20 amp wire directly bolted to the fuel tank.
the sensor arm is not stuck as i made sure it had plenty of space when installed

how should i go about testing with a better earth? attach a jumper lead to the fuel tank and then to a - terminal on a battery? should i run a 20amp wire directly from the boats - to the tank?

thanks

 

[Texasmark]

Re: fuel gauge & fuel tank earthing issues

If I understand you, the actual sending unit only has one wire attached; the hot wire attached to the center insulated terminal which goes to the low side of the gauge with the other side connected to battery + voltage, usually switched via the engine start/run switch.

You close the circuit (complete the current loop) via a ground wire attached to the tank proper but don't say where it goes.

What I always did was to put the ground (low voltage....return wire) lug under one of the screws that mount the sending flange to the tank which puts it in direct contact with the sending unit. The other end of that wire goes to the battery - or a remote ground terminal that is attached to the battery and provides a convenient point for numerous instrumentation return wires to attach at a common point.

HTH,
Mark

 

[Georgesalmon]

Re: fuel gauge & fuel tank earthing issues

Remember you still need a bonding wire directly from the tank to the fill fitting for static electricity plus what Texas is telling you for the sender. If you are using rubber fill hose that is.

 

[mr_plow]

Re: fuel gauge & fuel tank earthing issues

thanks mark i will try relocating the ground to one of the screws on the sender unit, currently the ground is attached to one of the mounting screws on the bottom of the tank.

 

[mr_plow]

Re: fuel gauge & fuel tank earthing issues

george the tank in under the bow and the filler is above on the bow connected by about 3 inches of hose. how can i bond and aluminum tank as it is just mounted to the deck?

 

[Georgesalmon]

Re: fuel gauge & fuel tank earthing issues

You run a wire from the tank body to the filler. Lots of boats have one of the screws that hold the filler on replaced with a bolt and the wire runs to the bolt under the deck with a second nut.

 

[Don S]

Re: fuel gauge & fuel tank earthing issues

Moved to electrical forum, this is not an outboard problem.

You must have a ground wire from the sender in the tank to the battery neg. You may be able to find a ground buss bar at the helm that will work instead of going directly to the battery.

DO NOT use the hull of the boat as a ground.

 

[Georgesalmon]

Re: fuel gauge & fuel tank earthing issues

Wasn't meaning a ground. Was talking about bonding wire from filler to tank to dispell static electricity from gas rushing down the rubber hose when filling.