Yamaha Fuel Management Gauge 6Y5-83500

[Inthehighlands]

These gauges are advertised by Yamaha as being suitable for 2 & 4 stroke models from 115hp upwards.

I'm trying to understand why there is the 115 upwards restriction as, from what I've been able to find out, they don't pick up any data from the engine.

My new (to me) RIB has come with Yamaha tachos and I'm hoping to install a matching Fuel Management Gauge. The engines are twin Evinrude 90hp ETEC.

Thanks in advance for any advice.

Inthehighlands

[fairdeal]

someone here knows, but until then,

I will guess that it has to do with the sensor's limit of capability at low fuel flow rate

in your case, tho -

if you happen to be feeding both engines from the same tank

you have a combined hp of 180 - well over that 115 limit

[Inthehighlands]

Thanks Fairdeal - sorry, I should have mentioned that the engines will be fed from separate tanks.

I wondered about whether the sensors might lose accuracy at lower fuel flows.

IntheHighlands

[fairdeal]

The engines are twin Evinrude 90hp ETEC.

what "model year" are those ETECs ?

[Inthehighlands]

The Evinrude engines are 2004 model year - with about 250 hours on each.

In an ideal world, I think I'd have looked for Yamaha 4 strokes, but they were available as a pair at a v competitive price.......

[fairdeal]

so pre-NMEA 2000.

Have you looked into Floscan ?

[Inthehighlands]

Hi Fairdeal

Thanks for your interest. Yes, pre NMEA 2000.

I've not looked around yet - as the existing tachos are Yamaha multifunction gauges, it would be nice to match them.

The Floscan 7000 unit looks best for my needs and with a HP range of 25-100HP covers my current needs. A bit annoying that I'd need 3 external switches, whereas the Yamaha unit is self-contained.

I'll see if anyone can help with my queries re the Yamaha gauge before further investigation of possible alternatives.

All the best

IntheHighlands

[Inthehighlands]

I bought one of the Yamaha Fuel Management gauges and am looking at installation. It all appears fairly simple, but i have 1 query.

It appears to get 2 +12V feeds :
- Yellow wire - from the ignition system when the keyswitch is turned on
- Red wire - simply stated as +12V

My GUESS is that the Red supply needs to be permanently live/on and is to ensure that data is retained whilst the engine is turned off.

I'd be grateful if anyone is able to confirm this - or provide an alternative view.

Because of the current wiring of the boat, it would be much easier if I didn't have to supply a permanently "ON" 12V supply!

Thanks in advance for any comments.

InTheHighlands

[fairdeal]

I never thought about it,

now looking forward to Boscoe or Rodbolt explaining

I believe the MFG tach and speedo also have the "red" connection -

and yet I (and many others) routinely kill ALL power with a battery switch

and never notice any difference with the gauges...

why does Yamaha do that?

[boscoe99]

Only the Yamaha digital display speedometer, fuel management meter and combo fuel management meter/speedometer use a red wire for battery voltage. For memory purposes.

[Inthehighlands]

Thanks Boscoe99 - not the news I was wanting to hear, but I did rather suspect it.

The boat has 2 heavy duty relays (one per engine) to isolate everything from the 4 batteries (2 per engine). So all the current wiring is disabled when the boat isn't in use. I'll look at picking up a fused +12V feed from one of the the feeds to the switches for the relays as this is the only permanent +12V supply on the boat.

As all the wiring is within waterproof enclosures, joined by waterproof cabling, mainly using MIL spec connectors, this isn't as simple as on most boats.....

Once again, thanks.

InTheHighlands

[fairdeal]

Only the Yamaha digital display speedometer, fuel management meter and combo fuel management meter/speedometer use a red wire for battery voltage. For memory purposes.

I'm puzzled by the older document showing - as you state - no "red" to the tach



while the newer "on-line" rigging guide shows that it does:



(Now, one tach is -90, the other -91)

But regardless,

as to the "digital analog" speedometer - what is it using the red wire to "remember"?

I don't have one any longer; but when I did,

I never noticed that turning off the main battery switch made any difference ?

[boscoe99]

For the speedometer I am thinking it is for the clock memory.

For the tachometer I think the coloured illustration you have latched onto is incorrect. The document which contains that illustration was ginned up by Yamaha USA. Not Yamaha Japan.

Here is what Yam Japan shows for the wire colours for a -91 tachometer.

[boscoe99]

I'm puzzled by the older document showing - as you state - no "red" to the tach

If you put faith into any Yamaha document you can very well be puzzled. Maybe the japs are getting back at us for winning the war.