Help with fuel sending unit

[raysbigfish]

I have a 2001 (2510 Parker ) with twin Yamahas. My fuel gauge is blinking with one bar. Can someone please tell me where the fuel sending unit is located.please be specific. The boat original seats wave been altered with a plate on the deck and shock seats. I don't know is a hatch used to be under the plate. Much appreciated.

 

[Antidote]

One blinking bar means either your fuel level is below the sender or the float has sunken. Do you know how much fuel is on board? You could have as much as 40 gallons and be below the sender depending on the length of the sender.


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[Brent]

Fuel sender is located under a cockpit deck hatch. If none are presented, then remove items to find. Blinking light means low fuel. How low? You don’t know. The fuel tank pickup doesn’t reach the bottom of tank and a lot of gas is usable. Fuel sender is an electrical item and the blinking light means a certain resistance value measured in Ohms.


How Does a Fuel Sending Unit Work? The fuel-sending unit is a potentiometer that is adjusted by a float attached to a rod exactly like the float in a toilet bowl. When the fuel in the tank drops in level, the arm with the attached float correspondingly drops, which changes the amount of resistance in the potentiometer.


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[Brent]

Do you mean, it is blinking all of the time ? You add 60 gal of gas and light still blinks?


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[raysbigfish]

I just filled it up. It’s 160 gallon tank. My boat is a 2510, so it used to have the big box looking seat base. But at some point, they were replaced with a plate and the shock seat mount. I don’t know if the hatch your talking about is under them?

 

[Brent]

Any Pics?

I thought in the center line of the boat between the seat bases, there two or more deck hatches.

 

[Brent]

On this 2510, I see two round deck hatches and one
rectangle.


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[raysbigfish]

The only hatch, is for gas cap hose to tank , no access to anything else

 

[Brent]

The only hatch, is for gas cap hose to tank , no access to anything else

Do you have an aft hatch to access the batteries and bilge pump? Open it, stick In head or camera and use flashlight to locate sender.


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[Brent]

If the tank is made by RDS, contact them with HIN for tank drawing.


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[raysbigfish]

I think that’s my best bet , to contact the gas tank manufacturer. Thanks for your help, appreciate it.

 

[Antidote]

This is the fuel probe from my 2019 2520XLD. The float is the black thing at the bottom. It would be reading a flashing single bar in this position. It is 13” long. The tank is 16 5/8” deep. I installed a 16” prob to be more accurate.


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[Brent]

Thumbs up. How long are the fuel pickup tubes?


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[Antidote]

Thumbs up. How long are the fuel pickup tubes?


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Not long enough. To find out my usable fuel, I ran her dry after filling until she clicked off. I let her settle and squeezed a little more in. I used my Sea Tow membership to get some gas delivered. :shock: My usable fuel is 160 gallons. That leaves 19 gallons unusable. And that was with the 16" probe flashing one bar.

 

[Brent]

Thanks! Great info.


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[johnfbushjr]

I never did see a response that said what your problem is but I think you are saying your gage always reads empty. If you think you have a problem its not too difficult to troubleshoot once you locate the sender. Basically you remove it from the tank and manually move the float to the top then bottom of the unit while your helper observes the gage on the dashboard. For safety reasons I would have a fire extinguisher close at hand whenever doing fuel tank work.

If it doesn't look right the next step is to determine if it is the sender, the gage, or the wiring in between. To check if it is the sender you can cut the sender's leads and use an ohm meter to measure resistance with the float in both positions. Most units in the US use the 33 to 240 Ohm standard (google your model number to double check). Since you already have it removed from the tank at this point then for safety reasons don't take any chances with an open fuel tank ... you should remove the sender from the boat and take the Ohm readings on the dock. And again have a fire extinguisher close by just in case.

If the sender checks out okay you have a problem with the wiring or the gage itself. You'll need to check the continuity of the wiring next. If it checks out the gage is the culprit. My problem was the opposite of your problem. My tank always read full. It ended up being a $0.50 bad butt splice between my sender and the wiring running up to the console. Hope this helps.