Fuel Gauge Type?

[AlastairLC]

Does anyone know what type of fuel gauge was used by Oday on their 322s or similar models and how they work? Mine looks to be mechanical but there’s a ground wire attached to it and some sort of knob.

Before I try to take it apart, I’d really appreciate any advice. Thanks.

 

[Gene Neill]

I beat my brains out several days last month on the subject of fuel gauges. They *seem* to have an SAE standard for the cutout and the bolt pattern. The space between the bolts is not equal, there is one wide spot so the gauge cannot be installed in the wrong orientation. Looks like it's the 7:00 spot in your photo.

Therefor, I *think* this would be a drop-in replacement for your gauge: https://www.jamestowndistributors.c...7107&familyName=Moeller+Mechanical+Fuel+Gauge

 

[AlastairLC]

Thanks, Gene. I’ll look into that.
I just don’t understand why a mechanical gauge needs a ground wire. And what’s that knob thingy?

 

[Tally Ho]

It should have a red marker that shows the fuel level. But it is hard to see. I have to crawl into the lazzarette with a flashlight to see it.

Cannot comment on the wire or knob, other than to say mine has them too. Maybe a ground wire?

Greg

 

[AlastairLC]

I’m going to crawl down there Monday. Try to figure it out.
Does your work, Greg?

 

[Tally Ho]

Yes it works, but as you know, hard to get to and harder to read.
I see the red “flag” in your photo (blew it up to see it). Right hand side down by the “knob’. I can’t remember which side indicates “full”. Is your tank full in that photo?

Greg

 

[walmsleyc]

That's a moeller electro/magentic/mechanical gauge.

- Remove the two phillips screws and the whole top part (gauge) will pop off.
- Hard to see, but there is a red needle/pointer to visually show you the level
- The fuel will still be sealed below
- The float mechanism in the tank is coupled to the gauge via magnetism
- The alloy plate with 5 hex screws separates the mechanical float (and it's magnet) from the top gauge (which is controlled by the magnet)
-There is a gasket between the alloy plate and the tank that keeps the fuel where it's suppose to be
-The top gauge also has a resistor in it, and will read from 33-240 between ground and the corroded brass bolt/stud to indicate the fuel level (you can connect this to many different gauges)

You can buy replacement top gauges with or without updated resistors (slightly different looking design that your older version) and it should fit exactly back on the old alloy plate. If you remove the plate, then maybe best to have a new gasket ready (commonly available). Probably no need to remove the 5 hex screws and the plate. Ground wire is common and I think ABYC requires it on diesel tanks even though there is not the spark hazard that there is with gas.

Cheers
Chris

 

[AlastairLC]

Many thanks, Chris. Wow! You are a wealth of information. Now I know what to look for and how to do it.

 

[AlastairLC]

Is your tank full in that photo?

That’s what I’m trying to figure out. Despite recent contracted filling, the engine quit on the way out of the marina. (Sailed back to the slip okay.) Turns out, the vent was clogged so fuel couldn’t get into the tank or into the engine. The spiders must have been busy.

 

[Tally Ho]

So I pulled the top off my fuel gauge this weekend, and found it exactly as Chris described. The could be the best tip I have gotten all year!

Assuming my gauge works, and the resistor does its thing, hooking up an external fuel gauge should be a simple task and not require a new sending unit.

I will try to test the resistor with a digital multi tester when I am out st the boat next. The unit is labeled 240-30 ohms. I see lots of external fuel gauges available that work in that range.

@walmsleyc - thanks for the best hack ever!

Greg

 

[Maine Sail]

All you should need is a new conversion capsule.

 

[walmsleyc]

To follow up .... I tested my original, and it appeared to give reasonable readings, so I connected it to a gauge and quickly found that my original was flaky. I presume because the resistor coil inside had become dirty or corroded. The reading would vary from open circuit to something approximately reasonable. I discovered this upon refilling the tank and attempting to calibrate the gauge reading with the number litres in the tank.

In the end, I ordered the module that Main Sail noted. They don't sell one that looks like yours any more (with the contacts for an external gauge being a brass stud). The price for the electronic sender is about 3x the price of the visual only sender so be aware!

Chris

 

[AlastairLC]

I couldn’t get the top gauge off mine. The rim seemed to be hard soldered in. So I extracted the whole unit. Turned out it was working fine (the gauge moved smoothly around the dial as I moved the float up and down), but it’s so hard to read the dial that I ordered a whole new unit. All parts available on Amazon.

 

[Tally Ho]

Hmmmm, well mine seems very clean. The brass stud is clean.

I think I will try hooking it up to a gauge and see if it works.

How does that Capsule thing work? And how does it attach to the sight gauge?

@AlastairLC - did you ever figure out the reason for your engine issue? Not out of fuel I assume.

Greg

 

[AlastairLC]

did you ever figure out the reason for your engine issue?

Clogged vent, Greg. Seems the spiders were busy in there.

 

[Tally Ho]

Those €’@&#$##”-+@&%= spiders!

Greg

 

[walmsleyc]

Hmmmm, well mine seems very clean. The brass stud is clean.

I think I will try hooking it up to a gauge and see if it works.

How does that Capsule thing work? And how does it attach to the sight gauge?

@AlastairLC - did you ever figure out the reason for your engine issue? Not out of fuel I assume.

Greg

Just hookup a multi-meter (in resistance mode) between the brass stud and the outer metal case (one of the two screws holding the module down). The red indicator and the internal reostat are one and the same (mechanically tied together inside the clear plastic housing. The magnet (attached to the float mechanism) below moves both the sight gauge and the reostat together.

If you remove the module to test, then you should find a magnet that you can hold under the module and rotate. You should see the red indicator and the resistance reading change together as you rotate the magnet.

Chris

 

[Tally Ho]

Just hookup a multi-meter (in resistance mode) between the brass stud and the outer metal case (one of the two screws holding the module down). The red indicator and the internal reostat are one and the same (mechanically tied together inside the clear plastic housing. The magnet (attached to the float mechanism) below moves both the sight gauge and the reostat together.

If you remove the module to test, then you should find a magnet that you can hold under the module and rotate. You should see the red indicator and the resistance reading change together as you rotate the magnet.

Chris

Great. I will test it out this weekend. Worse cas sounds like one of the new site glasses with the capsule that Maine Sail mentioned. Is there more than one size?

Greg

 

[Tally Ho]

I was able to put my digital meter on the gauge, and move the marker around with a magnet and the ohms changed. Looks like it is working pretty well, so will get an electronic gauge and mount it.

Is there an easy way to get power from the engine control panel for the electronic gauge. I would only want it on when the engine key is in run position.

I have a Yanmar 2GM20 and the panel looks pretty close to this one...
https://goo.gl/images/y2FjiJ

Greg

 

[AlastairLC]

Greg,
I’ve been trying to figure out what that toggle switch on that panel does. I can’t read the writing on your linked picture. What does it do?