Fuel Tank Sender Question

[Bob S]

I am going to install a new sender and have a question. The old sender is an arm type and I want to install a tube type that Capt Patrick recomends. (ISSPRO) I noticed that the there appear to be 2 studs on top instead of the one on my current set up. Is the second one just a ground? If so where to take it, to a neg bus or just to the bronze plate that it is mounted to? I assume the old one didn't need it because the base was metal as oppsed to plastic. Also what is the correct ohm rating? Thanks for any input.

[Bob S]

ISSPRO also has volumetric and non volumetric senders. Which is the correct application?

[CaptPatrick]

Bob,

Can't answer your 2nd question off the top of my head, but call ISSPRO & ask for their tech dept. They are real friendly and can answer more questions than you can ask... 888-447-7776

The contact on top are + & -

Br,

Patrick

[ianupton]

I spoke with ISSPRO a while back about this.

If I recall correctly, the volumetric is for tanks that are round in the cross section. This sender apparantly compensates for the x-section.

Give them a call, they will answer for sure.

Ian.

[Sean B]

Bob

On the ISSPRO sender I installed a while back, the two contacts were ground and ground lead to the gauge. The sender is just a big variable resistor, and the gauge is reading and reporting what the ground resistance is. Connect the sender wire you have to ground and your gauge will move to either full or empty, depending on which way it is set up.

So you need a direct ground on one contact, and there is usually a wire on the bronze plate on the top of the tank. I added another wire from that ground line to the contact on the top of the sender.

If you don't have a ground wire to your old sender, or to the bronze plate top on the tank (where your old sender picks up it's ground from it's mechanical connection) then it probably fell off, and no sender is going to work without re-installing it.

The guys at ISSPRO could not tell me which ohm range my sender was as they are all different. I just got the gauge from them that goes with the sender. BTW I wired it up with the original gauge and it didn't work quite right, 1/2 tank reading on the old gauge actualy meant near empty tank in my case.

[thereheis]

when measuring for the sending unit ,i need to measure for m the top of the plate or bottom ...

phil

[CaptPatrick]

Phil.

Measure from the top of the bronze manifold plate... The correct length of the sender tube should extend to as close to the tank bottom as possible without touching.


Br,

Patrick

[Peter]

Any wire that attaches to the bronze plate on your fuel tank is probably part of the bonding system, and while the bonding system does connect to the electrical ground, it isn't supposed to be used for carrying any current under normal circumstances.

Run the ground for your new sensor directly to an electrical ground. Pay attention to wire colors, as black is no longer always ground!

Aslo make sure that there is indeed a bonding wire from the bronze plate to the bonding system of the vessel. All metal parts in the fuel tank need to be bonded to prevent sparks due to static buildup. There should be a sytem connected to the filler plate fitting on the deck, to the bronze plates on the tank, to the metal baffles inside the tank (assuming you have an original Bertram fiberglass tank,) and from there to the bonding system for the rest of the vessle.

Peter

[scot]

I gave up on sending units a while back...when they came out with Floscans. 100% more accurate and just one less place to leak on the fuel tanks. I'm addicted to knowing within .0001% of exactly how much fuel I have used and how much I am burning at any given time. I've had one failure in the last 5 years and the company made it right.