1974 Evinrude 2hp 2402 "Mate" Won't Start When Hot otherwise runs great

[FlexWiggles]

The good news: I rebuilt the carb/carb gaskets, replaced the impeller, replaced the lower unit-to-engine gasket, changed the spark plug, checked the points gap, checked the water flow, added fresh fuel, gave it two pulls on full choke and BINGO! -- this little engine runs like new.

The bad news: IT WILL NOT RESTART WHEN HOT. Here are some diagnositcs. 1) plug is dry and caramel brown. 2) tried a hot lean restart with no choke and open throttle with no effect 3) new impeller is producing good water flow at top of tube.

The ONLY way it will restart is if allowed to cool for 20 mins, or more immediately if I wet it down externally with a spray bottle of water (which works fine in a pinch, but other boaters witnessing this look at me cross-eyed).

Interestingly it runs continuously for long distances -- indicating to me it is not running so hot that it will stall out. However it is obviously too hot if restart is impossible. It needs to be cooler for sure, dontcha' think?

Questions: 1) might a different oil mix help cool it? Say 1:25 instead of 1:50? 2) There is a hole in the lower unit-to-engine gasket which restricts water flow to the back of the head. Perhaps I could open this hole up to let more cooling water flow? Other ideas?

 

[F_R]

The most common cause of hot start problem is a bad coil.

 

[FlexWiggles]

Thank you. I guess I had not considered electrical since I see good spark. Can you suggest parts to order? For instance do I need a whole kit of some kind with points and the whole works? Thanks

 

[racerone]

Bad condenser.

 

[oldboat1]

Think I would just replace the coil, condenser, points. If the head is too hot to touch at any point, the motor is running too hot. With an IR gun, should see readings around 130-140F. Think I would run the specified Champion J6C plugs gapped at .030. Would stick with 50:1 with TCW3 2-cycle oil (heavier ratio will likely just foul the plug). Continued overheating may mean that impeller installation should be revisited, including water tube grommets. If it's a salt water motor, you may have to go through the water passages and clean out salt deposits.

 

[racerone]

I recall asking folks to tell me the story when they brought their lawn mower into the shop.-----Whenever someone told me ---" I cut the front yard , stopped the mower and went to the backyard and it would not start "-----We installed a new condenser and no more issue.----That same shop is still in business today , same family since 1968.

 

[tomhath]

If it is running hot another thing to check is to pull the cylinder head and see if the water passages are packed with silt.

 

[FlexWiggles]

Great thread and thanks for responses. Before I order points and condenser I remain curious about why I get good spark in hot condition? I pulled the plug to confirm this. If condenser is bad in hot condition, why do I see spark? Not questioning the voices of experience here, just aiming to understand (which is half the fun).

 

[racerone]

Many people have been fooled by spark on a plug grounded to the block.------Does spark jump a gap of 5/16" as it was designed to be able to do ?