2300 CC Fuel Gauge

[johnfbushjr]

I'm having trouble getting an accurate reading on my fuel gauge. It is very slow to drop and won't drop below about 3/4 tank or 5/8 of a tank. I don't have an FMS so its very difficult to tell how much fuel I've used or have left in the tank. Its a year 2000 hull with 2003 Yamaha gauges. Any tips on where to start? Any have similar problems? Any tips on removing the sensor to see if the float is working right?

 

[warthog5]

Replace the sender.

Remove the sender. Use a tape measure and stick it in the sender hole all the way to the bottom to get tank depth.

Then go to this site and order the one that is correct for your tank depth.

https://www.amazon.com/Moeller-035765-1 ... way&sr=8-1


But while your there.......and BEFORE you take it apart......... with Power ON.....IGN key ON and Pink wire removed from center of sender. Touch it to GND [Ground] Gauge should sweep all the way to Full.

This will test the wiring and the gauge.

Another note: There are 5 screws thru 5 holes that hold the sender in the tank.....It only fits One way. Sometimes it is hard to see if all holes are aligned correctly. I clean the tank area and the sender before trying to remove the screws and put a Witness mark with a Sharpie Marker beside 1 screw and the tank. This helps on a reinstall.

I have seen tanks screwed up, because people did Not install the sender correctly and one hole was misaligned. So they just crammed a sheet metal screw thru the hole.

 

[Brent]

Warthog. You use Moeller instead of WEMA?

Do you install a longer fuel pickup tube to increase usable fuel capacity?


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[johnfbushjr]

Thanks for the advice Warthog. I'll take a look tonight after work and report back.

 

[johnfbushjr]

Warthog I didn't find a pink wire. I found a WEMA SUF 15.5 with a blue and black wire (see pics). I assume I should put the blue to ground to verify my wiring?

 

[Brent]

Here is an article

https://marinehowto.com/testing-a-marine-fuel-sender/


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[Brent]

From WEMA

http://www.wemausa.com/faq/#.XRzPTWcpCf0


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[warthog5]

Warthog. You use Moeller instead of WEMA?

Do you install a longer fuel pickup tube to increase usable fuel capacity?


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Yes...Had problems with WEMA units.

No...Typically they will not fit correctly....They are designed to be 1 in off the bottom.

You measure the tank depth....Then buy the unit that says that depth, but it's actually 1in shorter.

Yes I have tried to do the exact depth....Sender would not pull down correctly.

I even have one in my '55 Ford Hot Rod.

 

[warthog5]

johnfbushjr

You will have to cut the Blue to Pink connection.

That sender has been replaced before.

You will GND the Pink wire and watch the sweep of the gauge.

 

[Brent]

Warthog

Is this worthwhile?


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[warthog5]

Never even seen one till now. LOL

 

[johnfbushjr]

Strong northeaster yesterday on Lake Erie so all fishing plans were cancelled and I had time to troubleshoot my fuel problem. Here is an update ...

We cut both wires at the butt connection at the sender end of the system (in the photo above) and the gauge reading immediately went to empty. So we figured the cause was a faulty sender as we suspected. So we took the sender out of the tank and just to be sure checked resistance. Much to our surprise it was working properly, so we figured the cause was wire continuity or the butt connection in the photo above. We weren't exactly sure how to check the continuity of the wiring ... so we re-did the butt connections and with the sender out of the tank manually cycled the float up and down. The gauge reading followed ... so it appears the root cause was the butt connection. Doesn't make sense to me because I would think that a poor butt connection would mean there is more resistance in the circuit and the gauge reading would be lower then actual. My problem was the opposite, the gauge reading appeared higher then actual.

We also noticed a slight build up of metal dust on the sender float, similar to what you would find on a magnetic crankcase drain plug. Maybe that affected the output of the sender. Not sure but it appears everything if functioning properly now, thanks to all for your help.