3.0 mercruiser key switch

[grizzreaper]

Good morning to everyone. So far so good on the donor motor. I have put my wiring harness on, it's all wired n ready to go. This motor came with a backyard key switch. I thought the switch was bad. So I wired in a new switch. If I jump the starter she cranks and fires right up. I turn the ign key I get nothing. Thought solenoid was toast so I put a new one in. there is four post on this key switch and three on other. Three post has Bat,Sol,and Ign. Four post has Bat, ACC, St, and Ign. What wire numbers go to what post. Thanks again for all your help. Hoping to put her in the water next weekend.

 

[Scott Danforth]

Bat is Red
ign is purple
Start is yellow with red stripe
Acc is orange

Check your MOB switch

 

[grizzreaper]

I have power to the batt. When I turn the key I have power to ign. Then turn key I have power to Sol but starter won't ingage. Stupid ? What is a mob. Man over board or kill switch. There is none. I have the motor on a stand and a old engine harness hooked to it. Is there another wire I need hooked up for the neutral switch.

 

[grizzreaper]

I should said power to batt. Then turn key to acc I have power to batt and Ign. When I fully engaged key I have power to all three. But starter still won't engage. If I jump the starter it will fire up. If I disconnect the homemade key switch from harness and jump it , it will only run if I continue to jump starter if not it dies. Does that make sense to anyone

 

[Bt Doctur]

power COMES FROM the battery to the switch.Red to B on switch Purple to I on switch, Yellow/red to S on switch
No accessory position on engine system

 

[grizzreaper]

Ok I have it hooked up that way. Still won't engage the starter. Not sure what the problem is. Yes I have changed key switch and still the same problem

 

[achris]

Check the starter is grounded properly.

 

[Bt Doctur]

where are you jumping the starter at, The starters solenoid or the slave solenoid

 

[grizzreaper]

I am using a screwdriver from battery lug to small yell/red wire post. Do this she fires right up. It is serial# 6783746. Which I believe is a 1984 3.0 140 hp mercrusier. From starter I have battery,50 amp breaker, and orange alt wire. Small outside post which is left side is yell/purp which goes to 12 volt + side with red wire to distrub. Solenoid had left side #6 red wire big post to harness. Right side yell/red wire to right side of starter. Small yellow/ red wire from harness to solenoid. And grounded from #1 black harness

 

[Scott Danforth]

the S terminal on you starter (yellow/purple wire) supplies +12 volts to the coil when cranking

the purple wire from the ignition switch should go thru a resistor wire to supply about 9 volts to the coil when running

it sounds like you do not have power in the run position.

 

[Bt Doctur]

if your jumping at the starter and it works, go to the slave and jump the large slave lugs,if motor spins then take a jumper wire from the + battery and touch the small yellow/red at the slave. Motor must spin

 

[Bt Doctur]

follow the blue lines click to enlarge

 

[grizzreaper]

Thank everyone for your help. I grabbed a different wire harness. Rewired it. Put the three wires on the key switch. Hooked up battery. Turned key n boom she ran. Thanks everyone for all your help.