1983 Evinrude 9.9 Bottom cylinder Cuts out

[phil chieco]

Hello, I have a 1983 Evinrude 9.9 horsepower that when put under load seems to run on one cylinder. New pugs have been installed and I checked bother spark plug wires and they are fine. I swapped them and the same thing happened. On a cold start runs on both cylinders but after a few minutes only runs on the top cylinder. Did a compressing check and have approx 105 in each. I have spark on both spark plugs when placed against the block so I'm confused. I'm not sure whether it's the coils or the power pack or something else. Is there a procedure that I can check both the coils or power pack?

 

[oldboat1]

Spark should jump a 7/16" gap (call it a half inch) using an open air adjustable tester. That would tell you the ignition is producing the energy needed.

The thermostat is at the bottom of the head, and can be difficult to seal. Take the head off, and while working on the bench take off the t.stat cover. Look for a broken t.stat gasket, incorrect torque or similar. Its possible that water could leak into the lower cylinder, so important to check. (Lower two head bolts are removed from the threading but left in place while the head cover is lifted out vertically.)

 

[phil chieco]

I will pick up a tester however if water is getting into the cylinder wouldn't the spark plug have a different color than the other one? Thank you

 

[oldboat1]

Likely would, but worth checking for air or water leak, imo. (The newer models have the t.stat up at the top.) Check the operation of the t.stat while there, then replace gaskets and torque to specs. I had issues with an '83 losing water into the pan.

 

[phil chieco]

By the way I did another compression check and interesting that the top cylinder was at 90 and the bottom cylinder was at 120. I did it several times I got the same readings. I'm guessing that if there was water in the bottom cylinder it would read a higher compression number. By the way do you know what the torque settings are for that year and model engine I do not have a engine manual.

 

[racerone]

With those compression numbers I would take the cylinder head off.----Inspect cylinder walls.------Easier to do the thermostat and cover when cylinder head is off.---And I do not believe water in the bottom cylinder will change compression here !

 

[phil chieco]

Thanks for your quick reply. I will get at it this coming weekend. Do you happen to know the torq settings for that motor E10RCTR.

 

[CatTwentyTwo]

The manual for my old 84 9.9 calls for 18-20 ft lbs on the head bolts, I would imagine it's the same for your 83.

 

[phil chieco]

I picked up a spark plug tester and it's definitely the lower coil. The top coil was able to jump the spark at 7/16 the bottom coil I had to pretty much put it almost touching the pen the PIN before it would spark. Thanks for your suggestions