20hp mercury thunderbolt

[bamaguy78]

I have a old merc 20hp tiller handle with serial number 5410042, not sure on the year but I think its a late 70's. my problem is I want to add electric start to it and ive got everything I need to do it but don't have a wiring diagram in order to wire it up, all I can find online is the diagram for one with steering wheel and not a tiller handle any help?????

 

[oldman570]

Re: 20hp mercury thunderbolt

You can modify the wiring diagram for the steering consul unit and just wire the motor for the ignition switch , by using short wires from the motor to a switch. Then wire the rectifier thru the switch in order to charge the battery. The use of a good four wire outdoor rated automotive trailer cord, or marine wire that can be bought here on Iboats will do the job. This will let you mount the switch in a convent location in the boat. You can also place a man over board switch on the motor, at the same time, for a safety measure. JMO
Oldman570

 

[bamaguy78]

Re: 20hp mercury thunderbolt

You can modify the wiring diagram for the steering consul unit and just wire the motor for the ignition switch , by using short wires from the motor to a switch. Then wire the rectifier thru the switch in order to charge the battery. The use of a good four wire outdoor rated automotive trailer cord, or marine wire that can be bought here on Iboats will do the job. This will let you mount the switch in a convent location in the boat. You can also place a man over board switch on the motor, at the same time, for a safety measure. JMO
Oldman570

Thanks! 2 more questions, is there some where I can look up my serial number to see exact year of my motor and do I have to use a rectifier?

 

[racerone]

Re: 20hp mercury thunderbolt

Motor appears to be a 79 model.-----A rectifier is part of the battery charging system.--Charging system is not needed to make a motor as electric start only.

 

[carholme]

Re: 20hp mercury thunderbolt

Your s/n comes up as:

20 200/20 2-cyl 5183393 5606491 1979 USA

From here:

Mercury 2-takt, 2-cyl, 18-25 hp, produktions?r, modellguide

Parts List:

MERC 20 - Mercury, Mercruiser, Force, etc. Parts Lookup

See rectifier as item 3 under ELECTRIC COMPONENTS

If you need the engine to charge your battery, yes, you will need the rectifier.

Gerry

 

[bamaguy78]

Re: 20hp mercury thunderbolt

Thanks for all the help guys!