Fuel gauge dead, any hope?

[Bigjim]

I replaced my fuel gauge but it still doesn't work. How hard is it to replace the sending unit in the fuel tank?

Are there any other options? The tank is situated directly under the cockpit sole and has only a few inches of clearance.

The fuel is diesel, if that helps.

[Badsanta]

Originally Posted by Bigjim

I replaced my fuel gauge but it still doesn't work. How hard is it to replace the sending unit in the fuel tank?

Are there any other options? The tank is situated directly under the cockpit sole and has only a few inches of clearance.

The fuel is diesel, if that helps.

I would check all connections. Do you have power to the gague ? Maybe a bad starter switch, get a multimeter and start testing.

[GordMay]

Basic Troubleshooting of Gauges:


Testing All Gauges:

1. Remove Sender Wire from “S” Terminal on Gauge, and Turn ON Instruments Circuit.

2. Test Voltage between “I” Terminal (External Power Supply) and Ground Terminal “G”.
Tested voltage must match nominal voltage of the Gauge (ie: 12V Gauge must test between 10 - 16VDC), and the Battery Voltage.
If no voltage - check Ignition or Instrument Switch(s) and/or Fuses.
If tests less than battery voltage, repair or replace (Violet) wire from Ignition or Instrument Switch.

If a Sender fails “Open” (Infinite Resistance), one or both (if Dual Station) Gauges will read Zero Scale.
If a Sender Fails “Closed” (shorted - Zero Resistance), one or both Gauges will read Full Scale.

Other confusing Ohmmeter results, such as readings lower than expected, could indicate a poor Ground Connection at the Sender Body (Sender to Engine Block). Check for pipe dope or tape on Sender Threads.

Testing Fuel Gauges:

1. Disconnect Pink Sender Wire from Gauge, and turn power ON.
The Fuel Gauge should read ZERO Scale (< Empty)

2. Short the Gauge Sender Terminal to Ground.
The Gauge should read FULL Scale (> Full).

3. Measure resistance of Pink Sender Wire to Ground.
American Floats: 240 Ohms (Empty), 103 Ohms (½ Full), & 33 Ohms (Full)
European Floats: 10 Ohms (Empty), 95 Ohms (Half), & 180 Ohms (Full)
Automotive & other Float Switches may use other resistances such as 0 - 90 Ohm, 73 - 10 Ohm, & etc.

4. Disconnect Pink Wire from Sender on Engine Block.

5. Test continuity of Pink Wire.
Zero Ohms from Block End to Gauge End - If not, repair or replace Wire.


6. Measure Resistance from Sender Terminal (on Block) to Ground on Block.
Should read as per (3) above - If not, replace Sender.

More info’ at:
Basic Engine Gauge Theory and Testing ➥ http://www.cruisersforum.com/forums/...sting-645.html

[ranger58sb]

Originally Posted by Bigjim

I replaced my fuel gauge but it still doesn't work. How hard is it to replace the sending unit in the fuel tank?

Are there any other options? The tank is situated directly under the cockpit sole and has only a few inches of clearance.

The fuel is diesel, if that helps.

If the sender is inserted into the tank at the same place that you have easy access to -- i.e., so that "only a few inches of clearance" doesnt matter -- replacing the sender can be easy.

For ours, it was disconnect pos/neg leads, unscrew sensor flange, remove sensor and gasket, insert new sensor and gasket, screw it down, remake connections, done. FWIW, we used new WEMA sensors, and most gauges are said to be compatible with them. Just get the right resistance patterns for your gauge (ours use 240 Ohms empty/33 Ohms full).

-Chris

[FionaJC]

I think that Gordmay has it pretty well detailed only the colours of witres may be different. Mine are all red, just numbered.

[boeing1]

You did not state what your fuel gauge is reading, would follow GordMay post, most cases bad wire connections

[Over Budget]

I’ve the same problem, and hear Tank Tender is highly recommended. No electric connection is necessary and it can monitor any number of tanks, including fuel, water, holding, etc. Apparently it’s extremely accurate. There is a video on You Tube showing how it’s installed so even someone like me that’s all thumbs can do it. Check it out.

[davil]

[QUOTE=Over Budget;2668305]I’ve the same problem, and hear Tank Tender is highly recommended. No electric connection is necessary and it can monitor any number of tanks, including fuel, water, holding, etc. Apparently it’s extremely accurate. There is a video on You Tube showing how/QUOTE]

looks interesting
prices found
https://www.fisheriessupply.com/tank...k-tender-panel

[OldGreyB]

Originally Posted by Bigjim

How hard is it to replace the sending unit in the fuel tank?

The tank is situated directly under the cockpit sole and has only a few inches of clearance.

.

GordMay has posted good instructions to confirm if it's electrical or wiring issues. Once you have confirmed the wiring and electrical is all sound and working, and the sender is definitely faulty, then it's only a matter of replacing the sender. As this was also part of your original post, and others have noted the same issues, I will enhance on ranger42C accurate response of replacement of an existing unit.

Firstly use an inspection mirror or your camera phone and if you are lucky the brand and part number be visible on the top , so you can order a replacement and have that on hand when you remove the offending unit. See wema: Liquid Sensors - Marine Diesel, Fuel, or Water Level Sensor or for a range of products https://www.westmarine.com/sending-units

There are many types on installations to the top of the tank, those with many small set screws, those with hex head and 1 &1/4BSP thread below, those with square heads and 1 &1/4BSP thread below. If yours has the large thread below, you have to hope the original installer used good quality anti seize compound, as they tend to bind over time overtime. If they are of that type a large spanner or rigid pipe tool on the square flats, or a 2" (50mm) socket if it is a hex head will (eventually) get it loose. Depending on the age it may take a bit of effort to get it to move. Large sockets are normally available from a local hire shop with 3/4" drive. One just needs at 3/4" to 1/2" drive adapter to fit the socket to a normal 1/2' breaker bar to move them. https://www.harborfreight.com/12-in-...bar-67933.html

Ensure on re-installation of the sender you use some anti seize on any threads to help the next owner in many years time.

As long as you have sufficient head room between the top of the tank and the bottom of you sole, its's easy to remove the sender once loose. Worst case at this point is if your builder did not allow the head room to get it out. Then there are probably only three options if staying with the same measurement system: 1) Can you move the tank sufficiently to get the head room. 2) You gradually remove the existing sender and cut pieces off the vertical length as you go, (Don't drop pieces into the tank) Then replace with another suitable float sender that will fit in the existing head room. 3) You have to make a new hatch in the sole to replace the sender! The later I have achieved with careful measuring to the center of the unit, and using a large hole saw or jigsaw, cut a hole in the sole to allow removal of the unit. There are many makes of nylon or stainless inspection ports that can then be retrofitted to the sole with the correct fasteners and adhesives.

So no, not all hope is lost. You can get accurate fuel measurement again.

[Bigjim]

Originally Posted by boeing1

You did not state what your fuel gauge is reading, would follow GordMay post, most cases bad wire connections

Gauge reads empty. No movement or life no matter what position the ignition is in

[smith8273]

I replaced my sending unit in about 20 minutes, bought the replacement at West Marine.

[Tom_F]

Is there a switch? My fuel gauge is connected to a switch that has to be held in the on position in order to read the fuel level. You hold the switch closed and the gauge and sender get power. Takes only a second or two to read the fuel level once the switch is closed.

[Bigjim]

Originally Posted by Tom_F

Is there a switch? My fuel gauge is connected to a switch that has to be held in the on position in order to read the fuel level. You hold the switch closed and the gauge and sender get power. Takes only a second or two to read the fuel level once the switch is closed.

There is a switch that looks manually installed aftermarket. I don't know what the switch does. But I will try it today when I'm on the boat.