2002 Mercury 115 four stroke with Yamaha powerhead

[FishinFool]

In 2002, Yamaha apparently made the powerheads for Mercury 115EFI four strokes. My buddy has trouble with hotstarts when the motor is shut down to change skiers, etc. He almost runs the battery down trying to restart the motor before it will restart. If the motor is allowed to cool down (20 mins) it will restart.

Anyone else out there have this problem?

Thanks,

Tony

 

[Rubber Biscuit]

I Have an 03 Merc 115 EFI.......Just the opposite problem.....Once started (which sometimes is a problem), It's fine....IF you let itr warm up, no problem restarting. If by chance you shut it down before warming up, it takes FOREVER to restart...I am thinking it might be injectors, plugs etc....don't know. Bought mine used as well....

 

[Genelie]

I have the same 2002 merc.....never had a problem cold or hot....may just be your unit. hope you get it it figured out.

 

[HighTechRedneck]

some random ideas

wet spart plugs from leaky injectors.
have him prime the ball to see if it help. it could be loosing pressure when shut down.
fuel filter
wireing problem in the ignition system.


I have seen a similar problem 2 times befor on a car. one had a bad fuel pump and the other had a bad distrubitor.

Hope this helps and good luck.
HTR

 

[Dave LeGear]

Hot starting problems are many times fuel related. When a hot engine is shut off, the temperature of the engine and everything on it continues to rise for awhile (even worse for engine painted in dark colors) as the engine undergoes a period of "heat soak." This can cause fuel to boil inside the carburetor bowl, fuel lines and in-line fuel filters. When you attempt to restart the engine, "vapor lock" obstructs the flow of fuel and the engine does not want to start.This is much less of a problem on fuel injected engines because the fuel is usually under much higher pressure inside the injectors and fuel line. However, a fuel line routed near an exhaust manifold or a fuel rail that's exposed to a lot of heat "may" still suffer the same kind of problems. Heat soak problems such as these can sometimes be cured by...

• Checking for factory installed or wrapping "insulation" around affected fuel lines, and/or installing an insulating spacer or heat shield near the carburetor.
• Making sure none of the intake manifold bolts are loose causing a "lean out" condition.
• Using a higher detergent fuel to help remove carbon deposits that may be causing engine knock and ping which also cause cylinder head temps to soar. Before the clean up is done though, one may need to run a higher octane rated fuel...
• Making sure you are using the the correct heat range of spark plugs and that those plugs are clean and the plug wires are in good shape and not breaking down under heat and load. Most times though, worn plug wires cause high speed running issues before they would create a "Hot Soak" type of problem. One has to remember or take into consideration though that electricity always follows the path of least resistance

Hard hard starting many times tends to be a seasonal problem, but may be worsen in the early months of spring when refiners are switching fuel blends. Gasoline refiners produce fuel with a slightly lower volatility rating (called "Reed vapor pressure") during hot summer months because lower volatility fuel is less likely to boil and cause hot starting problems. During the winter, they switch to a higher volatility fuel because it makes cold starting easier. But if you still have "winter" grade fuel in your tank when warm spring weather arrives, you may experience some hot starting problems. The problem should go away as you burn off that winter fuel and fuel up as the refiners in your area switch to their summer grades of fuel.

Hot starting problems can also be caused by cooling problems (thermostats out of spec) that allow your engine to run too hot (the pistons swell up and may scuff the cylinder walls), or excessive resistance in the starter motor that causes the engine to crank slowly. A starter "amp draw" test can be used to check the condition of your starter. Also, some starters have small "heat shields" to protect them from heat radiating from nearby exhaust pipes or manifolds on some engines. If the shield is missing, the starter may get too hot and bind up. Another item to check is all of your engine grounds, make they are all clean and snug.

 

[jebsr50]

don't rule out a weak coil

 

[Dave LeGear]

Yep, I have had a coil "burn" me more than once . Usually though the coil would create a spark when the plug was pulled out of the engine an laying on the block. But as soon as you re-installed the plug the coil would not have enough guts to fire the plugs... That will have you chasing your tail for a while that is for sure! Ha-Ha..