90 hp mercury won't start.

[Joeltawes]

Let me start by saying I don't know very much about boats or motors lol this is my first boat and decided to upgrade the motor.. Found a 90 hp mercury from CL. Got it as a project. Now I'm stuck lol. 0D136181.. New battery, starter, plugs and controls...the motor turns over very slow almost like a dead battery but when I take one or two of the plugs out its cranks strong in the cylinders that the plugs are out of.. Someone suggested airlock and adjust the timing but I just don't know.. Please help!

Thanks

Joel

 

[oldman570]

Re: 90 hp mercury won't start.

If the motor will spin over with the plugs out, then you will need to go through the starting system starting with a load test of the battery then clean all connections bright and shiny. Then check the solenoid and starter for bad/burnt contacts or brushes. It could be that the timing is out of sync and will need to have a link & sync done to get everything as it should be. JMO
Oldman570

 

[Joeltawes]

Re: 90 hp mercury won't start.

If the motor will spin over with the plugs out, then you will need to go through the starting system starting with a load test of the battery then clean all connections bright and shiny. Then check the solenoid and starter for bad/burnt contacts or brushes. It could be that the timing is out of sync and will need to have a link & sync done to get everything as it should be. JMO
Oldman570

The battery is brand new as is the starter.. The solenoid and all contacts look cleaned and free of corrosion

 

[oldman570]

Re: 90 hp mercury won't start.

If the motor timing is set to fast then the motor is trying to fire the cylinders before they need to and a link & sync needs to be done. Do a search of the forum and there are several post as how it needs to be done or get a manual for the motor here on Iboats, and it will have detailed instructions as how to do a link & sync. You will probably need the manual for future work, and it is a cheap investment for motor DIY's. It usually cost less than $25.00 and can be bought at some parts stores locally. It could also be that some of the plug wires are not on the correct plug firing order. JMO
Oldman570