470 wont start when its hot

[1977 SILVERLINE]

I have an old 1977 silverline boat with a 470 merc in it. The boat has 488 hours on it and is in nice shape. It runs really good. The merc has a closed cooling system and runs steady at 160 degrees. My trouble is when the outside temp gets into the 90s it is hard starting and sometimes won't start at all. If I leave it sit for 30 mins or so it usually will start, but not all of the time. I have put electronic ignition on it, a new coil, re-timed it to 4 degrees, changed spark plugs, and leaned out the rochester carb a little. The engine will either fire and quit right away, or sometimes the engine will start and when you put it into forward it will die.


Thanks for any suggestions

 

[stonyloam]

Re: 470 wont start when its hot

If you used a Petronix, you need to run a full 12V to the coil +. Splice a stranded (not solid) wire into the choke wire and run it to the coil in place of the resistance wire. This should help. It also sounds like you may have a shift cable problem, where it is stiff going into gear and activating the neutral cut off switch.

 

[1977 SILVERLINE]

Re: 470 wont start when its hot

Sorry, I ran a new wire from the ignition switch to the red ignitor wire and I am still running the original resistance wire to the 1.5 ohm coil.