Barely turns over or not at all after engine is warm

[mustacheyouaquestion]

I've got an 87' Mercruiser 4.3LX Thunderbolt ignition that I recently purchased. Ive done a little work to it buy replacing solenoids, new oversize marine battery with new connections etc. When cold it will fire right up with and issue. The outing before last I had shut the engine off a few times here and there and noticed it was slow to turn over but enough to start the engine. When I got home I put the water muffs on and it turned over just fine and fired right up. My last outing was the same, fires right up without issue and we go out tubing. After 45 minutes of running we stopped for a short while and it was slow to turn over but did start. Another 30 minutes of running I stopped again only the this it would barely turn over and starts clicking process. All the battery connections are tight and new and the volt meter shows a good charge. After periodically trying to start I had to get a tow. When i got home, I gave the ignition a bump and it starts right... I'm confused and afraid to take the boat back out until I learn a little more.

 

[Watermann]

Have you checked the ground cable end on the motor?

Did you pull the starter and have it bench tested?

 

[wahlejim]

Have you load tested the battery? Voltage is one thing but cranking amps are another and that is where you are getting your power for the starter. Also, as mentioned before, get your starter tested. Heat does strange things to worn out solenoids and motors, and it sounds like after a cooling off period, they are working fine.

 

[biggjimm]

Definitely check that ground cable connection at the block. Take it off & clean everything to shiny bare metal.

Usually that's an indication of a bad starter, if connections are good, but it also could be that the timing is off. If you just purchased this boat, I'd check that too, just to make sure.

 

[mustacheyouaquestion]

Thanks for the replies so far. I will start with the simple things and I will clean the ground wire connection to the block.
The starter looks like a real PITA to access but doable so that will be my next step.

 

[joetheis]

also after checking ALL the connections, (don't look, pull them, sand them reinstall) fire it up and check the timing.
Too far advance, it fire cold run awesome, but, be hard to crank hot.
One way to tell a poor connection is after a bit of cranking that connection (the poor one), will be warm or hot to the touch, same with a weak started, touch end plate, housing.
Joe

 

[Alumarine]

I'm not sure if it applies to the thunderbolt but with a points system if the timing is off it can impact starting when the motor is hot.
It fires off as the piston come up.