Spark test and engine becomes stubborn when warm

[wf2tm51]

how do i test for spark on an inboard engine generally speaking? also my friends dads boat has serious trouble starting when warm, it will work fine untill it is turned off but as soon as he trys to crank the engine over it becomes stubborn, i think if we test for spark and can't get it when its warm it's an electrical ignition problem input would be grealty appreciated

[hansp77]

my old engine doesn't like to start when warm either.
It is a stuart turner two stroke 8hp inboard.
The solution to this is and always has been to keep a few extra spark plugs handy and swap a cold for a hot one when trouble arises.
To test for your spark just unsscrew it and hold it into the socket then put the spark end near some metal- eg the engine. If you turn it over you should be able to see a spark jump to the metal object.

It would be usefull if you said what sort of engine.
Hans.

[marshmat]

The old hold-the-plug-against-the-block-with-a-screwdriver test will confirm if a no-spark condition is present, but seeing a spark certainly does not guarantee that the ignition system is OK. Put another way: if you don't see a spark then something is definitely shot, but if you do see a spark that doesn't rule out ignition trouble. It's far easier for even a lame ignition to throw a good spark at atmospheric pressure, than at 9 atm pressure inside the cylinder. An air-gap plug tester can give you the answers here, but some engines can be damaged by air-gap checking and so this might be one for a mechanic if you don't have the shop manual and the mechanical skill.

[stonebreaker]

What do you mean by 'stubborn'? Does it crank OK but just won't start?

I would think, since it runs OK once you get it started, it's probably a fueling issue instead of an ignition one. Is it fuel injected, carbed, diesel, gasoline...?

[wf2tm51]

well its gasoline cause it uses a spark plug they said once they try to start the engine when warm it takes a while to get it to kick over basiclly when the engine cools again it will start

[alex fletcher]

Its probably running rich my friend check you carburetor

[Frosty]

Try to give some clear information. Is It carb or fuel injection? What engine is it? What do you mean it takes a while to get it to kick over? Do you mean the engine wont turn fast enough to start? But does when the engine is cool?
Do you mean cooler or cold? How long does it take to cool enough to start?

Do you mean the engine will not crank over the first compresion when hot?.
If so you have a cranking problem. Have you tried jumping it( with jumping cables to the battery) If that cures it you need a new battery and reset the charging rate. If it wont crank over its compresions then it doesnt matter if your rich lean or have a spark --it still wont start.