1999 Sea Doo Challenger 1800 1 Engine Wont Start

[lowmans1966]

So I recently bought a 1999 sea-doo challenger and have been having issues getting the port side engine to start. It has started a couple times for a short period of time but usually it will turn over for about a second or two and then the starter just hums and the alignment shaft/flywheel stops turning.

I have checked the following:

-Battery was slow charged and load tested and checked out ok.
-Retried starting with charged battery and same symptoms appeared.
-Removed spark plugs and there is spark. Alignment shaft turned fine by hand with spark plugs removed.
-Tried starting again and shaft turned using the start switch with plugs removed.
-Reinserted spark plugs and attempted start. Starter would not turn the shaft for more than a couple seconds.
-Shorted the starter solenoid with spark plugs inserted, and the shaft turned fine.

Does anyone have an idea what the issue is or what my next step should be before throwing parts (new starter solenoid/new starter) at it?

edit: To clarify, this is the dual 787 engine setup.

 

[rusty nail]

did you check all your connections? Pull apart and a little sand paper to clean off corrosion, residue? could be bad grounds?

 

[jts32]

Since you have one good running motor, you have all the parts you need to determine what the issue is before randomly throwing new parts at it.

Try swapping the starter solenoid from the other motor and see if you have the same issue. And make sure the plug connection on the solenoid is not corroded

 

[lowmans1966]

Thanks for the suggestions. I took apart the connections and they looked clean and shiny but i decided to sand them a little anyway. After putting it back together I could get it to start with a little throttle and no choke.

Then I realized it was idling right around 900-1000 rpm and stalling out. Took apart the air inbox to find the idle adjust screw and moved it to set idle right around 3000 rpm on the trailer.

Now to get it out on the water this weekend and fingers crossed, it will run better than last weekend.

On the plus side, I am quickly learning about this boat and its systems!