Testing Yamaha fuel flow sensors

[Scott_K]

2000 Cobia CC twin Yamaha F115's

I recently went through all my gauges and fuel system on my boat. The flow sensors had the connectors cut off of them and wired to a separate harness going to the helm because the original harness had chafed spots.
I took apart the fuel flow sensors, cleaned them, and put new o-rings in both. Put together, no leaks.
I sent my gauges off (round multifunction) to be refurbished and wired everything back up correctly.

When I power on the keyswitches, the FMM gauge shows 0.0 GPH. If I start the starboard engine it shows the same even after running for several minutes. If I start the port engine, the FMM goes from 0.0 GPH to a dashed line. Only when I turn off the port engine does it go back to 0.0 GPH.

How do I test the fuel flow sensor output? Is it a voltage? I have a violet, orange and black wire on each one.
Any help appreciated to test the sensors or gauge. I didn't change any dip switches.

 

[QBhoy]

Must admit...I don’t know in this case. I know that my fuel flow reading is taken from the ecu and calculated by injector pulses opening and closing and likely an algorithm for proportional RPMs. Maybe yours is that or perhaps just a mechanical sensor like an actual paddle in the fuel line.
Someone on here will know. Put it in the yamaha outboard section. Plenty of experts take note of things on there.

 

[Scott_K]

OK thanks I will move the topic and yes these have a paddle wheel to detect flow. All seems in order with them

 

[southkogs]

I moved the topic and consolidated it to one for ya'.

Welcome aboard.

 

[Scott_K]

Perfecto!!!!

 

[Scott_K]

Well this weekend I will just remove the sensors and play around with getting resistance readings from the sensors. I don't want to apply voltage to anything and smoke one, if I haven't already.