Fuel tank sender issues

[shanagolden]

Fuel gage on my new Seaward engine instrument panel stopped working - just reads empty (my tank is full). Followed the steps in the tech wicki. Ran new wires for the sender connection and the ground to be sure. Still all the way to left. Installed a Moeller sending unit that I ordered from the West Marine catalogue that specified 240-33 Ohms. When I received the sending unit the packaging indicated 240-35 ohms. After hooking it up, I still get a reading all the way to the left. The gage seems to be fine, since it used to work and I jumped the send contact to the ground it went to the right (full). I'm stumped. Anyone have any suggestions. In the teck wicki the test procedure indicates that a Stewar Warner sender with 240-33 ohms should be used - since the one I installed goes to 35 ohms, could that be the problem ? Thanks for your comments.

[Ron Hill]

Shan : It sounds to me that you got a bad (new) sender !

[Indian Falls]

I just went through all this on my tub last fall.

2 ohms is not going to be the problem.  If you can get a volt meter that will read ohms it will help you a lot.
It's my opinion that a sailboat should have this tool on board any way.

The meter measures ohms by putting a small current/voltage on the meter leads. When you apply the leads to the device you're testing, the amount of current flow is displayed as ohms (long story short) .  If there is minimal resistance in the device, the max amount of current goes through the device and back to the meter and will be displayed as 0 ohms or in your case 33-35ohms.  Such as when the tank is full.  Your fuel gauge is at empty, so there  is max ohms appearing at your fuel gauge which is doing the same thing as I described the volt meter does (almost).   The problem sounds like a bad connection more than a faulty sending unit since you jumped ahead and replaced some wiring with the sender.  Your meter can also verify that the new sender is ok, by moving the float full range and watching the meter increase/decrease in ohms displayed. You'll likely see 240 to 34 ohms give or take 5-10 ohms.

How did you make your connections with the new wire?  Always go back to the last thing you did is my motto in trouble shooting.  If you need to splice wires on your boat don't use wire nuts, I don't even like solder-less crimp connections, I prefer to use a soldered "western union" (please google it) and cover with shrink tubing. 

It is entirely possible that your new sender is no good, but I think it's more likely something else.

Hope this helps!

[Ken Juul]

You have tested the guage and think it works.  Now do the same test, but use the entire wire run. Test the sender before it is hooked up.  One of the pieces of this simple system isn't working, just need to find out which one.

Western union splice.

[mainesail]

Guys,

The WU splice or lineman's splice is/was intended for solid copper wire not the type 3 stranding we use on boats. Beyond that the ABYC specifically prohibits the use of solder as the sole means of mechanical connection on boats. They also do not consider any form of wire twisting on stranded wire as a "mechanical connection"...  

As an an electrical systems specialist I see my fair share of bad soldering, and it is almost ALWAYS bad soldering... About 2% of the soldering I see done was done "correctly" the rest is a fire hazard... Those who know how to crimp, then solder, go for it but it needs to be done correctly and rarely is.....

If you don't know how to solder really well please don't learn on your boat. If you want to do your own wiring spend some decent money on a good quality ratcheting crimp tool and use quality connectors.

[sailaway]

Shana the easy way to check the gauge is to take a piece of wire and short out the sending unit to ground.  The sending unit has one wire in the middle. Just short it out to the metal tank. It should read full. That  is who the sending unit works . If that doesn't show full you have a bad wire or gauge. Charlie