Dead cylinder

[bufordg]

I have a 1975 --85 HP Evinrude that seems to have a dead cly. You can pull the plug wires off one at a time and all will make a difference except one. good fire on plug changed plugs, changed powerpack, and the coils. did a compression check average 115 pounds. Have cleaned carbs. starts good and idles good but still has a miss. does anyone know anything else to try. Thanks

 

[Bosunsmate]

Re: Dead cylinder

Run it with that sparkplug wire grounded for a few seconds. See if that sparkplug gets wet with fuel, light it to make sure its fuel.
check bypass hoses for leaks

 

[boobie]

Re: Dead cylinder

When it's running, squirt some premix fuel in the throat of the carb on the dead cyl once and see what happens.

 

[kbait]

Re: Dead cylinder

Check for quality spark on that cylinder... like 3/8" consistent bolt. If that's good, and compression is good for that cylinder, then it must be fuel delivery.. maybe a reed stuck open?

 

[bufordg]

Re: Dead cylinder

I will try that in the morning Thanks

 

[bufordg]

Re: Dead cylinder

checked the fire jumps about 7/16 inch 115 pounds compression

 

[Bosunsmate]

Re: Dead cylinder

check fuel as above, if its not fuel check timing on that cylinder

 

[bufordg]

Re: Dead cylinder

how do you check the timing? Thanks

 

[Bosunsmate]

Re: Dead cylinder

you need a timing light ($15)
mark tdc on the flywheel for each cylinder, check all cylinders are firing at same angle distance from the line ie the dead cylinders sparking is same relative to tdc as the other cylinders

 

[boobie]

Re: Dead cylinder

Read post # 3 again.

 

[bufordg]

Re: Dead cylinder

I finally got to try the gas spray today that seemed to help so took carb back off and went through again cleaned it again did not find anything visible but put it back on and it firing on the dead cyl now no3 cly is spitting when it is idling what am I missing in these carbs.

 

[emdsapmgr]

Re: Dead cylinder

When you pulled the carb down for inspection, did you pull the high speed jet of the bowl and visually check it to be sure it was clear? Spitting back through the carbs and be a cracked/broken reed. Or an indication that it is firing out of time. Check to be sure the flywheel key is not sheared.