6Y5 to 6Y8, will only the tac need the upgrade?

[Bahhhtlett]

Repowered from a salt water series 150 Yamaha OX66 2 stroke (1999) to a four stoke F150B manufacturered 10/ 2019.

I believe my tach and fuel gauges are 6Y5 generation, I know these don't have the command link capabilities. Would the 6y5 tach work with less functionality? Or will it not work at all?

If it is completely necessary to upgrade to the 6Y8 series, can I only the Tach? I fell like the speedometer and fuel readings are all separate from the engine harness?

[fairdeal]

your 6Y5 tach will still work with the F150:
rpm, trim, warning indicators for overheat & low oil pressure.

You will need to pop out the rubber plug on the back of the tach,
and change the settings;

you will also need an adapter harness, or cut and splice some wires,
because your OX66 had two plugs on the gauge harness,
and your F150 only uses one plug,
so the wires 'don't match' up directly.

Unlike a Command Link tach, which displays hours from the engine ECM,
he running hours are stored in the 6Y5 tach itself;
so you continue with whatever hours are in there now.

the old 6Y5 Speedometer doesn't need to be disturbed -
since it is not 'electrically' connected to the engine anyway
(although the rubber hose at the engine end will need to be connected to the F150)

If you want to go with a Command Link tach,
you will need Command Link wiring from the engine to the helm,
the existing tach harness will not work.

Are you aware that the Command Link speedometer/fuel gauge
is also a "fuel management " gauge?
So if you go with the CL tach,
you might want the CL speed/fuel gauge also.

If so, however, there is one wrinkle:
the CL Speed gauge does not use the rubber tube from the engine "directly"
the way the 6Y5 does -
so it needs either a $150 "sensor" at the engine to connect to the speed tube
or get speed from a GPS unit.

Which brings up the final point -
are you using a "NMEA 2000 compatible" GPS/chartplotter/fishfinder?

If so, you can connect that to the engine's Command Link -
and get the engine data - including fuel use -
on that non-Yamaha display
either instead of, or in addition to, Yamaha CL gauges.

[Bahhhtlett]

Huge thanks for the thorough answer.

Turns out, I am using a NMEA capable GPS unit. (GARMIN 546) Looking into that now, wondering if I can set it up to use as a split screen and save on purchasing new equipment to get the full benefit of the available live engine data.

I did plan to upgrade the GPS to a split fish finder/ chart plotter as right now the way the boat is rigged, my depth and fish finder is a secondary unit, and the 546 is chart plotter/speedometer. I'm wondering if this is all already possible with what I have.

What is the proper way to wire the engine to the NMEA unit? I see some starter kits out there, is that all that is needed?

If I were to upgrade, any recommendations on a unit that will display cleanly all at once that won't totally break the bank?

[fairdeal]

With the limited screen area of the 546,
I don't think a 'split screen' is possible
although you can select a few data bits to display across the top of the chart;



and then you have a "numbers' screen where you can select 6 pieces of data

[fairdeal]

and then there are two 'engine gauge' pages

[fairdeal]

My personal approach when 'upgrading' to NMEA 2000
was to stick with the original 6Y5 tach in place:
getting rpm and trim, always available & readily visible,
was my major interest anyway.

and then use the Garmin for fuel management (MPG, remaining range)
displayed across the top of the chart (as shown above).

I didn't feel I needed to constantly 'see' engine temp, oil pressure, voltage etc -
if I wanted to check those,
easy to switch to a different Garmin screen

[Bahhhtlett]

Thanks again for going above and beyond here,

Good to know you can run both at once- is there a plug in for the NMEA 2000 right on the engine just as there is on the GPS? is it simply one cord and it feeds all of this data? I'll have to poke around for a write on one setting up one of these networks.

[Bahhhtlett]

So I think my 6Y5 gauge is ancient, the fuel gauge was upgraded to a gauge with buttons but the tach does not have front buttons and there are only two dip switches on the back. I cant find the write up for this tach showing what these two dip switches are, anyone know what one I need to flip for the Four stroke?


tach1.PNG
Tach2.PNG

[Bahhhtlett]

Edit: Adding a helpful NMEA install video I found for a four stoke on a pontoon boat. Hits on all the right stuff for anyone else who might look at this post later on with similar questions.

https://www.youtube.com/watch?v=DkO9zaC04xk

Still not sure how you would run this and another Tach at the same time? don't they share the same Engine plug?

[fairdeal]

there are only two dip switches on the back. I cant find the write up for this tach showing what these two dip switches are, anyone know what one I need to flip for the Four stroke?

hmmm. I don't think I have any info that old - perhaps Boscoe does.

Your F150 requires two changes to a tach used on the 1999 engine -
2 stroke to 4 stroke of course (for the warning indicators)
and also 3-wire trim sender to 2-wire

one of the dip switches is almost certainly tach input: 6 vs 12 pole
that would not need to be changed

so with only 2 dipswitches - which function is "not there" -
what did not exist at the time the tach was made?

I'm inclined to guess the trim sender type -
as that change was made in 2001,
whereas 4-strokes go back to 1995

[fairdeal]

Still not sure how you would run this and another Tach at the same time? don't they share the same Engine plug?

That's the point of NMEA 2000 -
any connected device can share data with all other connected devices.

So you make one connection of the engine to the 'backbone',
the tach connects to the backbone,
the MFD connects to the backbone,
they both get to 'see' the data.

(and you connect power to the backbone;
the gauge of course needs that to operate,
the Garmin, although it has its own power connection,
connects via an 'opto-isolator' which keeps that power separate,
and needs power on both sides)