Fuel Management Display

[gtreanto]

I've searched the archives and found a number of posts that cover my issue. What I don't have is a wiring diagram. I looked at the latest 2016 Outboard Rigging and Parts and that pointed me to the different connection points. So I can see some wires go to the ignition, I see the wire connected to the GPS and the the six wires going back to the flowmeters. What I was wondering does anyone have a wiring diagram so I can tell what each wire does? I need to start checking continuity but I could check resistance on some of these if I knew what went where..

Oh BTW I have a 2003 Pursuit 2470 with Twin 2002 F115TXRDs and round Yamaha gages

Thanks.

[boscoe99]

I've searched the archives and found a number of posts that cover my issue. What I don't have is a wiring diagram. I looked at the latest 2016 Outboard Rigging and Parts and that pointed me to the different connection points. So I can see some wires go to the ignition, I see the wire connected to the GPS and the the six wires going back to the flowmeters. What I was wondering does anyone have a wiring diagram so I can tell what each wire does? I need to start checking continuity but I could check resistance on some of these if I knew what went where..

Oh BTW I have a 2003 Pursuit 2470 with Twin 2002 F115TXRDs and round Yamaha gages

Thanks.

I am confused. Do you want to check wire continuity or do you want to check circuit/device resistance? If resistance, what are you checking against? That is, what are the resistance values that you will be using as your standard?

Anyway, here is a diagram.

[gtreanto]

I figure you can do this two ways.

First disconnect both ends of the cable, jumper two wires and check for continuity. That way you don't have to run a wire to the back/front of the boat. The other way is to check for some resistance if you know the circuit. I will probably just check continuity.. Thanks for the diagram..

[gtreanto]

I continuity tested the six wires for the two

flow meters and everything checked out fine. FWIW there is 70 ohms resistance between the black and each of the orange wires. The purple wires show noting and I'm guessing some type of signal wire.

I doubt both flow meters are clogged. I am wondering if the con*****er went south. Has anyone seen that, is there a way to check it?

[boscoe99]

flow meters and everything checked out fine. FWIW there is 70 ohms resistance between the black and each of the orange wires. The purple wires show noting and I'm guessing some type of signal wire.

I doubt both flow meters are clogged. I am wondering if the con*****er went south. Has anyone seen that, is there a way to check it?

Orange wire with Yamaha stuff is normally five volts. Is that what you are seeing on the orange wire with the fuel meter energized?

I am thinking that as fuel flows through the fuel flow transmitter that the voltage sent back to the meter on the purple wire or purple/white wire varies based with the rate of the fuel flow. Based on the voltage seen by the FMM the gallons per hours are calculated and displayed.

Without knowing what problem you are having it is all but impossible to provide any sort of meaningful information.

[boscoe99]

FloScan Instrument Co. Inc.

[gtreanto]

The issue I am having is the fuel management gage

reads 0.0. It was working when we took the boat out for a sea trial, and I think it was working the first time we used it. It stopped working after I hit the sync button I think., I'll take a picture of the display when we go out tomorrow.

[rodbolt17]

its a simple 5v square wave frequency generator.

the flow sensor is a simple hall effect device .
as the paddle passes it drops rapidly fro 5v to 0 v and back to 5v.

the only thing common in the wiring is the ground wire.

[gtreanto]

what does the purple wire do?

the black is ground and I would expect the orange to be + for the hall sensor, but not sure about the purple..

[fairdeal]

the way I interpret this,

the orange would be the 5V "reference voltage" ("in")

and the purple would be the "5v to 0 v and back to 5v " ("out")

[gtreanto]

so if I was to scope this I would connect to the

black and purple and look for a square wave, or close to it.

[gtreanto]

Fuel Management is fixed

I brought the boat to a mechanic to have the port engine checked for vibration. While it was there I have them look at the fuel management system. They concluded the display was bad. They said they read a signal from the flow meters. I picked up a display off Ebay and it exhibited the same issue. The meter would do its BAT show 0.0 but when the engine/s would start the display would show --..

At this point I thought I would look at the flow meters. I pulled them and found each were clogged with varnish deposits. Cleaned them both out replaced the upstream filters and viola working Fuel Management system.

One last thing unrelated. The mechanic felt the vibration was caused by clogged injectors. So I have the guy do the VST and injector service. What a difference. Picked up approx 400 RPMs, the engines spin up much faster and are smoother. It was worth the money spent. Video of Fuel Management Display

[zenoahphobic]

Good to see fixed.

I would have added if it was not obvious, that the flow meters only put out a square wave signal when there is actually fuel flowing i.e. engine running.
At idle this would be extremely slow, and probably impracticle to do underway at speed. So disconnecting the meter and attaching some form of recirculating pump, or a gravity fuel feed would give you a better picture. You could also then take the opportunity to calibrate or check the continuing accuracy of these meters.

[gtreanto]

Square Wave

I agree. In fact I picked up a oscilloscope for my laptop to check this but never got around to it. You don't need to do anything fancy to check the electronics. Remove the flow meter, hook up a 5v DC source, hook up the oscilloscope, use compressed air to drive the emitter and you're all set. If you want to go this route.

For me it was pretty simple, since I checked the wiring, replaced the fuel management gauge so I was down to the flow meters. When I took them out and blew through the flow meter input I knew it was clogged. Blew a little harder and lots of varnish pieces came flying out. Once cleared you could hear the wheel spin. When the emitter spins it sounds like kazoo. So no need to go so deep as to pull out the oscope.

[rodbolt17]

you guys are killin me
O scopes and such.

it is a simple 5V square wave frequency generator.

if I want to get all impressive I would bust out the old CD-77 and watch the needle bounce.

as I am lazy I would most likely simply switch my trusty radio shack DVM to the Hz setting and simply observe it.

this stuff aint hard.
no need to make it so.