87 mercruiser 3.0 clicks but won't crank

[Donovan95]

My 87 mercruiser 3.0 will not crank over! I just bought the boat a little over a month ago and I've been out on the water about 10 times and this last time my boat would not crank and I had to get towed back to the dock. I've been reading forum after forum and I still can't figure it out I've already replaced the starter motor and Slave solenoid and I've tried jumping the battery I've looked at both ends of battery cables and everything looks clean and tightly secured. All I get is one click and nothing else. Any help would be greatly appreciated

 

[hoowahfun]

Have you had the battery checked? There is also another solenoid mounted near the red 50 amp circuit breaker on the engine, may want to check that.

 

[Donovan95]

The solenoid by the breaker is the one I replaced I haven't had the battery checked but I got it when I got the boat so I figured it was okay but I will goto a auto parts store tomorrow to get it checked

 

[alldodge]

The solenoid by the breaker is the one I replaced

Howdy

Jump across the top terminals of the slave solenoid (two large wires Red/Purple and Yellow/Red) and the engine should crank. If it does not crank over your missing 12V main power.

If it does crank over, then there are two small wires on the base of the solenoid (Black and Yellow/Red). The Black is ground and the Yellow/Red wire gets 12V when the key is turned to start

 

[andrewterri]

Have you check your key switch yet to ensure that is not your problem?

 

[Scott Danforth]

I would start by cleaning battery connections

 

[Donovan95]

Cleaned all connections had battery tested and still nothing. If it were my key switch would it still click back at the slave solenoid?

 

[alldodge]

Did you try jumping across the slave terminals mentioned in post 4?

 

[Donovan95]

Yes I did nothing happened I also tried jumping the positive battery terminal to the large terminal on the slave and got no spark could the new slave solenoid I picked up be faulty?

 

[alldodge]

Yes I did nothing happened I also tried jumping the positive battery terminal to the large terminal on the slave and got no spark could the new slave solenoid I picked up be faulty?

Here is the wiring for the start circuit. The slave solenoid has to large wires on it, Red purple and Yellow/Red. If you cross those two terminals its the same as talking a screw driver and crossing between the main starter post and the small left post.

If your unable to get anything by crossing those two then check your 50 AMP breaker, see if you have 12V on both sides. If no 12V is found there is a 90 AMP fuse on top the starter post, see if it has been blown. Being an 87 it might not have the fuse