Fuel filter water detection - question for Boscoe

[fairdeal]

OK so here's my latest zaniness

recap: my F225TXRD mfd 11/04 was built with the engine harness design for Command Link;
although the -30 ECU wasn't fully capable, I've replaced that with a -31 and enjoy the N2K output.

Unrelated, last fall, you identified one of the unused connectors on my engine harness as intended for the fuel-filter-bowl -water detector.



I'm thinking if it is for fuel-filter-water,
that on this engine, it is intended as a "Command Link" functionality;

so I'm wondering - what "signal" would the ECU receive
what is the exact nature of the fuel bowl sensor ?
Does it consist simply of two bare conductive terminals?

An obvious "exploratory technique" would be to simply drop that blue connector into a cup of water and see if the ECU transmits a "water in fuel" alarm!

but I'm hesitant to do that without a little better understanding of what I might be dealing with.

Any insights to share?

btw - here'a a summary of the parts listing for the F225 :



seems water detection wasn't added until April 2006, and there was a subsequent change, as well

[boscoe99]

A switch in the fuel filter cup closes when the cup has X amount of water in it.

Looking at the parts catalog the cup with a switch was introduced with a -32 ECU. Not sure if it will work with a -31 ECU or not. But you will know once you test it. And then you will let us all know.

Just jumper the two terminals together in the blue connector. Start the motor. Leave the gear shift in neutral. See if the horn sounds. If you hear the horn shift the motor into gear and let us know what you then hear.

Check your tachometer and see if it flashes the water in fuel warning, if the tachometer even has that functionality.

Keep on thinking.

Oh, there have been several changes to the fuel filter cup. Mostly to implement a material that would not swell in the presence of alcohol and cause the cup to be unscrewable. Then too, early sensor switches were known to have a high failure rate. The switch itself was improved for better reliability.

[fairdeal]

Success!!

Nice! As Boscoe advised, I just jumpered the blue connectors.

Engine does not need to be running - just key on. Immediate audible from the keyswitch horn.

No visual on the tach, but we knew from its "startup self-test" there was "nothing there". (Plus there's no hard wire to activate it)

But as I suspected, the N2K alarm is transmitted; once I enabled the Garmins they display it.

My next task is to come up an actual water "sensor/switch".

I don't want to use the engine mounted filter bowl,

I want it in the bowl of my boat-mounted 10 micron Racor.

(and of course the least expensive way!)

[boscoe99]

I forgot about the warning being available with just the key on.

Was the horn beeping or steady state?

Nice to see it on the MFD.

Here is what you will need.

REPLACEMENT BOWL FOR RACOR WATER SEPARATOR FUEL FILTER WITH SENSOR

Wiring is on you.

I hope the rodnut does not see the word "sensor" used on this sensor. Since the sensor is a switch. A switch being used as a sensor instead of being used as a switch. It will have to remain our secret.

Low, high, on, off, open, closed. It is no wonder we can't communicate. All the latest technology to do it with but we can't agree upon the words.

[boscoe99]

[QUOTE=fairdeal;118427]

My next task is to come up an actual water "sensor/switch".

I don't want to use the engine mounted filter bowl,

I want it in the bowl of my boat-mounted 10 micron Racor.

(and of course the least expensive way!)/QUOTE]

Far better IMO to have a water in fuel warning for the boat mounted water separating fuel filter than on an engine mounted filter.

Now I have such a deal for you. Deal for fairdeal. Get it?

I have sensor assembly that you can mount to the other outlet port of your Racor fuel filter. This sensor has a switch that will close if and when the vacuum (fuel supply restriction) rises to the point that it is excessive. You can wire the ground from the vacuum sensor assembly to the ground of the water in fuel warning sensor assembly. In this manner either sensor being grounded is going to trigger your water in fuel warning. When you get the warning you first check the clear bowl for water. If there is none and the water in warning sensor switch is open then you can suspect that the filter is excessively clogged or something further upstream is causing a restriction and closing the vacuum switch.

Actually, the water in fuel warning would activate any time there is water in the Racor clear bowl. Even with the motor off. If the motor is off there will be vacuum on the switch and it will be open. So, motor off and the warning, it has to be the sensor switch in the bowl. Because the vacuum switch will be open.

Let me know if you want the vacuum sensor and it is yours for the asking.