Wiring 1979 Chrysler 100hp to Yamaha Tach?

[JoshJK]

I have figured out that the white wire for my Chrysler outboard is the tach wire. Also, is it correct that this engine is a 12 pole?

I have the same tach referenced in the threads linked below. In these threads it is showing the tach set up for 6 pole for the Yamaha 70hp that I used to have. I am wondering if someone can help me make sense of these threads and tell me how/if I can wire my Chrysler to the Yamaha tach that is installed in my boat. Thanks

http://forums.iboats.com/forum/engi...ards/641912-yamaha-analogue-tachometer-wiring

http://forums.iboats.com/forum/engi.../373939-yamaha-85hp-tach-need-help-for-wiring

 

[JoshJK]

The way I am understanding this is I need to run 12volt positive power to the terminal marked 12. Then remove the jumper bar since my engine is 12 pole vs 6 pole. Hook ground from the Chrysler harness to the black wire and the white(tach) wire from the Chrysler to the green wire on the gauge?

 

[Frank Acampora]

NO, I don't think so-- try 12 volts to the terminal marked "B" Try white to the terminal marked "12"

Sometimes foreign engines use different colors than standard for power and signal. For example, black on automobiles is power, not ground (except for battery terminals.)

SO: I would try green for ground Black may be power to the light.

Let us know haw you make out. Also, try asking over on the Yammy forum--those guys should know for sure.

 

[Frank Acampora]

Cancel that advice! White is a signal wire that pulses 4 times per revolution, once for each cylinder that fires. It would be used on a Chrysler, Teleflex, or Faria tachometer with a pulse setting switch on the back set to "4"

If you are looking to power that tack, use the purple wire since this does come off your 12 pole alternator. That should give you the correct signal.

 

[JoshJK]

I have 12volts all the time on the purple wire. I am beginning to think that this tach is bad because I have tried almost every possible combination of wiring and still get nothing. I do get a variable voltage with my ohm meter when it is hooked to black and white on the Chrysler wiring harness.

 

[JoshJK]

I ended up just getting a Faria tach and wired it up. Works great but can someone confirm what I should have the setting on the back set to? This engine is 12 pole so it should be set on 5 correct?

 

[JoshJK]

http://faria-instruments.com/site_manuals/IS0086S.pdf

 

[JoshJK]

Frank can you confirm what setting I need the tach on? I am at the lake now and it is MUCH better with the Yamaha 17 pitch prop. Only thing is the tach is only getting up to 2000rpm with it set on 5 and that is at a speed of about 25-27mph. May just try the tach set to 4 since it sounds like the engine is running faster than 2000rpm

 

[JoshJK]

Just tried the tach set on 4 and am seeing a max rpm of 2600rpm at 25-27mph. Trying to figure out if the tach is right and if it is why so low of rpm at max throttle?

 

[NYBo]

They didn't have 20-pole stators back then?

 

[JoshJK]

Can someone please confirm my tach settings? I am wanting to get another prop ordered for labor day weekend if I need to I also think I may need to rebuild or clean the carbs since it get gas running out of the top carb after shutting the engine off

 

[JoshJK]

Should I be using the purple wire which should be an unrectified alternator signal instead of the white tach wire?)

 

[JoshJK]

Frank don't leave me now!

 

[Nordin]

If you have a 12-pol alternator set tachswitch on position 5 and try with the purple wire. The white tach wire comes from the CD box and you do not know what kind of signal it is.
Lock at the back of the tach. It says "Switch to match OB engine alternator".
I think you have to use an alternatorsignal.

 

[Frank Acampora]

If you have a 12 pole alternator (the engine will have a distributor) you can or should be able to use the white wire for signal with the switch set to "4" Now, I don't know Faria tachs and I have never seen a 12 pole outboard, meaning 12 cylinders or power pulses so I must assume that the tach is set up to run off the alternator. Try the purple wire to signal and set the switch to 12 poles See what happens. AND try to use standard color coded wire. Right now you have yellow to power, black to signal and green to ground. makes it confusing when the rest of the wiring can not be seen.

 

[JoshJK]

I usedd the purple for signal and set the tach back to 5 last night. Started it up quick and was showing 2000rpm at fast idle so I believe I have a that right now. Another question. What is the black "fin" that is added onto the lower unit for? Do I really need it or is it just adding more drag?

 

[NYBo]

It provides a little bit of steering but its main purpose is to protect the prop. It's called a skeg.

 

[JoshJK]

The one above the prop that is mounted horizontally? Looks to be something someone added on

 

[JoshJK]

You can kind of see it in this picture. At the left of the pic mounted on the flat above where the exhaust comes out.

 

[JoshJK]

Is this the skeg you were talking about or is it something different.