Fuel sending unit and fuel gauge issue.....

bgreene · #1 10-15-2015, 07:15 PM

Reads between 1/4 - 1/2 full but WRONG because I only had 5 gallons of fuel remaining in the 60 gallon tank ( it filled 55 gallons at pump )

I suppose i need to bend the float arm up a bit, but how much ?
Any ideas ?

1996 Wellcraft V21 specs indicate 60 gallon tank, not the 70 gallons some suggest.
So assuming the spec of 60 is correct, when I have less than 10% fuel remaining, gauge should read less than 1/4 tank .

phatdaddy · #2 10-15-2015, 10:08 PM

gas guages on boats are not very dependable. u could take your old one out, run it up and down and see if the needle reacts accordingly. i didn't have a gauge for 20 years. figure your mpg and set your trip odometer on your gps. with the old merc, i got 2 mpg, so i had a 120 mile range. the new motor has a smart guage that computes fuel useage and subtracts from the size of your tank and gives your fuel remaining as a %. i still set my gps and keep track of mpg.

bgreene · #3 10-16-2015, 03:46 AM

Ok, thanks

tsubaki · #4 10-16-2015, 04:25 AM

I would simply remove all the fuel, remove the sending unit, clean and inspect the bottom of the tank, replace the sending unit with a new one (making sure the float bottoms out correctly), with the tank level (manipulate the winch stand till so) start making notes at "E" and start adding fuel in 5 gallon increments and noting the locations on the gauge.

I've had two people complain to me about their boat getting good gas hours when they fill it up but then once they reach 1/2 tank the motor just eats up the remaining fuel quickly.

The belly tanks are not usually the same dimension/volume per inch of height therefore you would not expect the gauge to read correctly as to the actual fuel volume.

tsubaki · #5 10-16-2015, 04:37 AM

It has probably already been invented, so I won't ask for credit on it. A fuel gauge that can be calibrated at the 1/4, 1/2 and 3/4 marks.
Even MJ could calibrate it!
Picking on the 60 gallon fuel size just add fuel in 15 gallon increments and set the mark accordingly.
Or even one with a removable/replaceable face plate already calibrated for the differing tanks shape.

Blue_Runner · #6 10-16-2015, 12:37 PM

I just replaced mine. There was a calculation on the package. Also had the benefit of holding the new next to the old unit to compare. Old unit still worked perfectly but the design of top round piece (where the screws go) was terrible and allowed fuel to leak around the screw threads.

Mine was a Moeller.