I have a 35 fountain with twin 500hp mercs. When I try to start my starboard motor I get nothing. I try moving the shifter thinking it might be a neutral safety switch, still nothing. But when I start my port motor and then try to start the starboard motor the motor starts. Almost like the vibration from the port motor is making a loose connection start the starboard motor. Once the motors are running I'm good for the day. I can start the starboard motor any time all day long. But by the next day same problem. Any ideas would be greatly appreciated.

I'd start by cleaning the battery connections, and the connections at the starter, and the ground cable where it attaches to the engine block.

thanks for the fast responce. i tried all the above. any other ideas?

Maybe a bad battery? Have you tried switching the batteries around to see if the problem moves with the batteries? Just an idea... Hope you get it figured out, but I can feel too bad... at least you arent dead in the water... haha! Good luck my friend!

Maybe a bad ignition switch

This may sound dumb check the Battery cable connections to your battery, then if it is not that my Baja did the same thing. It turned out to be the SAFETY LANYARD SWITCH, fought that for 3 weeks of intermittent use before checking the simple stuff. It was a $14.95 fix.

Don't you love when that happens, a cheap, easy fix. Most things are actually.

Need more info, Will the starter crank the engine but just wont fire? If not can you hear the solenoid clicking? On mine the safety lanyard prevents the engines from running but will crank over all day.

I had an identical problem with my 2000 Formula, same engines, the problem was a bad fuel pump or ignition relay. I replaced both - they're both the same part number. I am assuming the engine cranks - wasn't clear to me in your note.