Fuel Gauge Issues (Both gauge and sender have been replaced)

[dacarter]

I've been trying to get my fuel gauge to work reliably since I bought my 03 Larson 274 6 months ago. It works sometimes when on the trailer, but almost never when it's in the water. I replaced the gauge first, then the sender but it still doesn't work most of the time. The wiring that I can see looks fine. There are some spade connectors near the sender and a couple of ground wires. Any ideas?

 

[crabby captain john]

Re: Fuel Gauge Issues (Both gauge and sender have been replaced)

Most often when it works only sometimes it is a ground issue. Check the connections 1st.

 

[alldodge]

Re: Fuel Gauge Issues (Both gauge and sender have been replaced)

I've been trying to get my fuel gauge to work reliably since I bought my 03 Larson 274 6 months ago. It works sometimes when on the trailer, but almost never when it's in the water. I replaced the gauge first, then the sender but it still doesn't work most of the time. The wiring that I can see looks fine. There are some spade connectors near the sender and a couple of ground wires. Any ideas?

Agree with CCjohn
Who is the manufacture of your gauge/sendor?

 

[UncleWillie]

Re: Fuel Gauge Issues (Both gauge and sender have been replaced)

It reads Full? Reads Empty? Jumps around?

Define "Doesn't Work"!

 

[dacarter]

Re: Fuel Gauge Issues (Both gauge and sender have been replaced)

"Doesn't work" means reads empty when I know there's fuel in the tank.

I agree it sounds like a ground issue, but as I said above all the wiring looks good, grounds are clean. The ground wires that disappear below the floor as they run toward the dash, may lead to a ground point somewhere besides the dash area not sure.

I find it interesting that it works out of water but not in water.

Sender is Wema, the type that has a float sliding up and down on a stainless rod. Not sure about the gauge brand.

 

[alldodge]

Re: Fuel Gauge Issues (Both gauge and sender have been replaced)

Looked up Wema and they use the North American standard 240 Empty to 33 ohm full scale. Using the standard there is a very good possibility your gauge has no issue with the sender. The pink wire goes to ground and the black goes to the gauge. When the boat will flex and sit differently on a trailer and the water. I'm figuring you have a pinched wire going between the gauge and sender. I would see if you can fish a new wire from the tank to the dash for the sender wire. Jumper it in and if it works great, if not use it as a new ground.

 

[UncleWillie]

Re: Fuel Gauge Issues (Both gauge and sender have been replaced)

It sounds like the wire TO the sender, or the ground AT the sender is Open (Broken).

Detach the wire from the sender and touch (Short) it to the sender body, and then touch it to the Battery NEG Post. (Extra wire needed).
The gauge should read FULL in both cases.

Post the results if you need help in interpreting the problem.

 

[dacarter]

Re: Fuel Gauge Issues (Both gauge and sender have been replaced)

Thanks for all the input. I'll try to take a look later today and snap a pic or two so you guys can see the wiring I'm working with. I'd really like to figure this out, but can't really test until the boat is in the water again. The guage and sender were replaced with identical units to stock, so hopefully they were compatible from the factory. It's an 85 gallon tank, but not sure if that makes any difference.

 

[dacarter]

Re: Fuel Gauge Issues (Both gauge and sender have been replaced)

Here are a couple of shots showing the fuel gauge working properly while the boat is sitting on the trailer, and the sender unit and wiring. Haven't done any of the suggested wiring tests yet.

 

[dingbat]

Re: Fuel Gauge Issues (Both gauge and sender have been replaced)

Here are a couple of shots showing the fuel gauge working properly while the boat is sitting on the trailer, and the sender unit and wiring.

It looks like you have the sender wired backwards. According the the Wema, the pink goes to ground and black to the sender. It looks like your Black is tied to ground and the pink is going to your sender.

 

[alldodge]

Re: Fuel Gauge Issues (Both gauge and sender have been replaced)

Here are a couple of shots showing the fuel gauge working properly while the boat is sitting on the trailer, and the sender unit and wiring. Haven't done any of the suggested wiring tests yet.

View attachment 213081View attachment 213082

Only thing I'm seeing is your BLACK wire is going to ground and the PINK wire is going to the sendor. According to WemaUSA they are connected the opposite of your method.

http://www.wemausa.com/instructions/WEMA_SENDING_UNIT_INSTALLATION.pdf

 

[dacarter]

Re: Fuel Gauge Issues (Both gauge and sender have been replaced)

I was careful to wire it exactly like it was with the old sender, took a picture and everything, but it could have been wired wrong when I bought the boat, so I'll give it a shot switching the wires. Hope it's that simple.

 

[dacarter]

Re: Fuel Gauge Issues (Both gauge and sender have been replaced)

Well, I swapped the wiring and water tested but it didn't work. I had to change the spade connectors to make the change because one was male and one female on the sender side. On the trailer it looked like it was working, correctly showing full, but in the water, the needle went way below E. With the old wiring it would have been closer to E.

 

[UncleWillie]

Re: Fuel Gauge Issues (Both gauge and sender have been replaced)

I don't understand what putting it in the water does???

What does the resistance of the two wires on the sender measure.
It should measure between ~240 Ohms Empty and ~33 Ohms Full.

Are you sure the tank is truly full and it is not just sloshing around giving false readings.
Boat fuel gauges are notoriously inaccurate due to the geometry of the design.
A half of a tank can read FULL or EMPTY depending on how the boat is floating.



Yours looks like the same sender I have.
It is just a group of magnetic switches in a tube and does not care about polarity.
Pull the sender and operate it by hand to confirm proper operation.

 

[dacarter]

Re: Fuel Gauge Issues (Both gauge and sender have been replaced)

I don't understand what putting it in the water does either, but as I said in my first post, the gauge usually works out of the water, and doesn't work when in the water.

I'm sure the tank was full.

I'll try to get some Ohm readings.

Operating it manually is a good idea, but again, it usually works out of the water, so it would expect it to function normally.

 

[UncleWillie]

Re: Fuel Gauge Issues (Both gauge and sender have been replaced)

... Operating it manually is a good idea, but again, it usually works out of the water, so it would expect it to function normally.

On the trailer you get one steady reading.
Operating it manually allows all the positions from Full to Empty to be checked.

Is the difference that, in the water the motor is running, and not running when out?

 

[alldodge]

Re: Fuel Gauge Issues (Both gauge and sender have been replaced)

I don't understand what putting it in the water does either, but as I said in my first post, the gauge usually works out of the water, and doesn't work when in the water.

I'm sure the tank was full.

I'll try to get some Ohm readings.

Operating it manually is a good idea, but again, it usually works out of the water, so it would expect it to function normally.

I'm still thinking the boat flexes (in/out water) and pinches a wire or something comes loose.

 

[dacarter]

Re: Fuel Gauge Issues (Both gauge and sender have been replaced)

Is the difference that, in the water the motor is running, and not running when out?

That I'm not sure about. Good idea... I'll hook a hose up and test.

 

[kahuna123]

Re: Fuel Gauge Issues (Both gauge and sender have been replaced)

Did my response get removed?

 

[dacarter]

Re: Fuel Gauge Issues (Both gauge and sender have been replaced)

Did my response get removed?

Kahuna123,

I don't think your reply ever got posted. I don't have it in my emails.