Fuel tank sensor problem

Hello all how are you?

since we bought our boat in august 2019 we spend so many hours on fixing and upgrading that finally 3 days ago we went out for a two week trip.
First thing we did was filling the diesel tanks. Already bought a new gauge and measured the sensors before.

while filling centre tank sundendly the gauge dropped to zero. Then some airbubble came and a lot of diesel came out the filling opening and then the gauge continued to full.

Port tank, no problems and gauge went to full.

Starport tank, same as centre but when gauge dropped to zero it stayed there.

Then when we hit the water and go in plane the Centre tank gauge dropped again to zero. Later it came back to half full and stayed there.

Unfortunate the sensors are on a position you don’t wanna access...

any thought what cause this problem?

thanks

Nobody knows how a sensor works?

Sounds like loose wire connection or bad rheostat in the tank sender (replace the sender)

First job after our two week trip: peeling carpet off to try to access the sensors. Misses will be happy again

for now, let’s rest some bit

The most common culprit is, as mentioned, the senders. However, before you did into that, the other two possibilities are the wiring to the gauges and the gauges, themselves. Try to eliminate/test the gauges, you can:

-- Swap the good gauge for one of the other ones to see if the problem follows the gauge or stays with the circuit.
-- You can also test the operation of the gauge. With power to the gauges (engine doesn't have to be on), jumper from the gauge's ground to the gauge's pink wire and the gauge should peg to full. If that still doesn't work, try another known-good ground.

Hello all
Have a 1999 410 express great boat.
My port fuel sender has gone out. Gauge is ok and works. Looks like there is no way to remove sender without cutting a hole in the floor. No room to replace a 24 inch sender once old one is removed.
Has anyone done this project?

Lazy Daze said:

The most common culprit is, as mentioned, the senders. However, before you did into that, the other two possibilities are the wiring to the gauges and the gauges, themselves. Try to eliminate/test the gauges, you can:

-- Swap the good gauge for one of the other ones to see if the problem follows the gauge or stays with the circuit.
-- You can also test the operation of the gauge. With power to the gauges (engine doesn't have to be on), jumper from the gauge's ground to the gauge's pink wire and the gauge should peg to full. If that still doesn't work, try another known-good ground.

Click to expand...

Few months ago I bought a new gauge and it works good. Port tank reads normal, centre en starport having problems with the sensors. In couple weeks I will post more with some photos.

After a few weeks relaxing with my wife on our boat and didn’t do major jobs that drive her crazy by pulling all the carpet I waited for the right moment. Today finally that moment came.

I thought it would be a hell of a job but it was a pretty easy job to access the hatches that revealed the sending units on a sea ray 500 da.

I started with the starboard sending unit and totally forgot that the tank was full with Fuel so by the second screw gasoline came out. Oops. Tightened the screws and continued with the centre tank. Unfortunately I forgot to take a picture from the unit but the cork was full with black bacterial gunk. I tried to clean it but when i touched the cork the metal broke. Lucky me that I checked it now because I know for sure that when I fill the tank full or hot some hard waves it had broken in the fuel tank.

I measured the depth of the centre tank (21,5’’) and put the unit back without the cork.

The port unit was a bit dirty. I measured the depth also (37cm 14.57’’) I cleaned it and put everything back.

Since the centre tank unit was broken I don’t want to take any risk and ordered new ones for all 3 tanks. I assume that starboard and port tank are the same so I ordered 2 13.5’’ sending units and 1 from 19’’.

Always order a new sending unit with 1’’ less then the tank depth. Especially with plastic tanks. It also gives you some reserve fuel when your gauge shows empty.

the original sending units are with a swinging arm. I ordered
Different model as in photo below. No swinging arm that can stuck somewhere so I hope it’s gonna work good.

Shipment will be delivered around 8 augustus so in my next update the results will follow.