Engine cranks over slow... (Like Vapor Lock)

[Musicripper]

Help!
I have a 120 Merc Force .... Was running fine, suddenly started cranking over like a low battery or vapor lock. Charged battery first, put a new one in, no change.
We came up with a system of me pulling the rope on the flywheel and my GF turning the key over at the same time. After a couple revolutions, it turns over fine. If it doesn't start right away, we have to repeat this until it does.
I pulled out the plugs, and it turns over fine.
Is this a fuel venting problem, or a timing problem? If so, how do you time this engine? I see the timing marks on the flywheel.
Anybody?

 

[CharlieB]

Re: Engine cranks over slow... (Like Vapor Lock)

Typical of poor battery cable connections (either end, either cable) or dirty starter brushes/worn commutator in the starter.

 

[mla2ofus]

Re: Engine cranks over slow... (Like Vapor Lock)

Typical of poor battery cable connections (either end, either cable) or dirty starter brushes/worn commutator in the starter.

Or it's like my Force 90HP starter. It just needed some grease in the front and back bushings.
Mike

 

[Jeremy90bay]

Re: Engine cranks over slow... (Like Vapor Lock)

I had this trouble with my 50 and had to remove the starter and clean between the block and the starter bracket. they are self grounding so the area needs to be clean.

 

[john from md]

Re: Engine cranks over slow... (Like Vapor Lock)

Has the engine been smoking alot lately? If not, then it is probably starter related, either poor connections, battery, solinoid or starter. If it has been smoking more that usual, it could be the fuel recirc system is clogged allowing the lower cylinder to load up with fuel. This slows cranking speed. This symptom can also come from a perferated fuel pump diaphram.

John