76 Evinrude 15Hp

[909]

Top cylinder won't fire.

Any suggestions.

 

[tphoyt]

Test coil or swap coils and see if the problem follows.

 

[909]

Thanks. What is an acceptable ohm range when testing the coil

 

[tphoyt]

Sorry got tied up.
How did you make out?
Not sure about ohm range numbers off the top of my head.
Swapping coils to see if no spark follows is just a quick check.
If it were me and this motor has not had any maintenance I would just pull the flywheel and replace everything and start fresh.
Is this motor new to you or is this a problem that just came up?

 

[Crosbyman]

start by comparing the ohms value of the good coil (boot to engine frame)

if identical suspect coil is likely OK

if suspect coil checks out as OPEN (infinity) start by simply twisting the plug boot , wire and coil end connection RETEST boot to engine frame
If OPEN (infinity) check plug wire end to end

measure coil High voltage plug end contact surface with engine frame .. if OPEN (infinity) coil secondary is open

if coil secondary checks out ok then problem likely under the flywheel.
or the coil primary is open (somewhat rare)

test and compare bad coil with good coil results .

Primary windings generally very low ohm secondaries very high (4-7 Kohms) on old style coils

on more modern coils could be 250-300 ohms

clean all surfaces/connections

visit Leroys site lots of info for you

OMC 9.9 - 15hp

 

[909]

Thanks for the replies.

Swapped the plugs and running beautifully now.

All 2 strokes want is to be ran wide open.

 

[oldboat1]

Well yes, but it should also idle smoothly. If the carb has been cleaned and rebuilt, try adjusting the mixture screw on the top a bit leaner (clockwise) until it lean sneezes (light backfire -- sometimes not so light) or stalls. Then set it about 1/4 turn richer (counter clockwise). rpm will increase with the lean adjustment -- lower the idle with the twist grip. (want about 650 rpm warm and in gear). Must go into gear smoothly with no stalling.

All adjustments on the boat in the water, or a test tank with the water level about half way up the leg.

 

[Crosbyman]

Thanks for the replies.

Swapped the plugs and running beautifully now.

All 2 strokes want is to be ran wide open.

strange conclusion ... a bad plug is a bad plug maybe the plug boot connection was oxydized a bit and cleared up while reconnecting. I would be on the lookout for a return of the bug

 

[OptsyEagle]

What spark plugs are you using? Just so you know those motors (1974-1976 9.9/15HP) hate Champion spark plugs. Always use NGK B6HS or B7HS spark plugs. Also, those motors should not be used for slow trolling. They like being run at higher RPMs. The problem with them is at slow RPMs the fuel does not burn well and the plugs will foul, very quickly (few hours of trolling) if Champion and a lot more hours if NGK, but will eventually foul if run or idled too long with any spark plug.

 

[oldboat1]

Try synthetic two-stroke oil, but plan on cleaning/regapping plugs as regular maintenance -- Italian tune-up after trolling.

 

[909]

Grazie Signore

Investirò in multipli

"Sparkplugs"

 

[909]

strange conclusion ... a bad plug is a bad plug maybe the plug boot connection was oxydized a bit and cleared up while reconnecting. I would be on the lookout for a return of the bug

Ran it open for 30 mins to the destination. The weather changed and cut our trip short . No choice but to "cruise" at trolling speed due to conditions, roughly 2 plus hours back to the marina. Your advice will help a lot of new users and shorten their learning curve . New Plugs worked.