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Posted

I have a 15 hp Evinrude, cira 1985, which started, when running down the lake at high speed (approx 10-15 minutes time), of loosing all power - continuing to run, but only at 1/2 speed. The motor then surges - ie a couple of minutes of no power then a 1/2 minute of high speed power.... I have had the carb cleaned and disposed of all fuels, drained hoses, etc and have started using a fuel additive (Sea Foam), but to no avail. I'm open to suggestions on what to look for in correcting this problem. It has been in a repair shop, but they keep saying it is an ethanol problem. Is there a hose or something between the carb and the cylinder that could be partially blocked? I'm open to suggestions .. comments appreciated.

Thank you.

Posted

let me be the first to weloome you to this site,

 

Ok guys, I have run this motor and believe me, you are taking a ride of a lifetime when it opens up without warning.

 

I know we have some pretty good mechanics on the board so lets give poor old weatherman an idea of what the problem could be.

 

and the motor in question is located in vermilion bay area so itisn't handy to any big city repair depots.

Posted

From your description it sounds like a fuel flow issue.

Fuel tank, fuel line, fuel pump are suspect if the carb was done.

If it takes 15 minutes for this to happen the tank may not be venting.

Did you try squeezing the primer bulb when it did this?

Posted

Welcome to our OFC Community Weatherman.

 

Not saying this is definitely the issue, but I had a similar problem and it was a lack of fuel.

Fuel pick up hose inside the tank had cracked right at the top. I guess sitting for prolonged periods, it had dried up a bit and when I ran the boat, the wave action moved it around until it finally cracked. Motor ran fine on a full tank, but once the tank was only 3/4 full, had a hard time getting the motor to stay running.

Pulled the fuel pick up assembly & fuel gauge off the tank (4 screws). Took the old line with me to Canadian Tire. Bought same size fuel line for a few dollars and cut a piece to replace the old one. Put it back together. Problem solved.

 

You can try adding rubber 'O' rings to either end of your fuel hose (tank and motor end) to make a tight seal to eliminate any possibility of an air leak at those points. Fixed an air leak on another outboard motor this way.

A repair shop should/would have checked for this, but just in case...................................

 

Good luck !

Posted

I would suggest, remove and replace with (known good) tank, and fuel line, in that order. If either one repair the problem, there is your solution. Ethanol fuel does nasty things to old fuel lines. Look them over carefully. And GOOD LUCK!

Posted

Fuel issue? Could be but I'm not so sure, the fact that it surges again kind of makes me wonder. If it just died down after a few minutes of running I would think OK engine is drawing more fuel than the fuel system can supply but since it pickes up again :dunno:....

 

Could also be an ignition coil breaking down on one cylinder as it heats up. That would explain the drop to 50% power then a sudden surge as it cools and starts to fire that cylinder again. An intermittant problem like that is something a shop might have trouble figuring out.

Posted

I had what sounds to be the same problem on my 25 Johnson (1985) and the problem was exactly what Cliff describes below.

Replaced the bad coil and never had any issues afterwards.

 

 

 

Could also be an ignition coil breaking down on one cylinder as it heats up. That would explain the drop to 50% power then a sudden surge as it cools and starts to fire that cylinder again. An intermittant problem like that is something a shop might have trouble figuring out.

Posted

From what I have read, if the miracle drug called Sea Foam didn't fix it it should be discarded to your nearest American friend... :whistling:

 

Hi Buddy, when can you drop it off... :D

 

Bob

Posted

let me be the first to weloome you to this site,

 

Ok guys, I have run this motor and believe me, you are taking a ride of a lifetime when it opens up without warning.

 

I know we have some pretty good mechanics on the board so lets give poor old weatherman an idea of what the problem could be.

 

and the motor in question is located in vermilion bay area so itisn't handy to any big city repair depots.

 

 

 

Thanks Bill ... thanks guys for the suggestions. I really appreciate your thoughts.

wxmn

Posted

Weatherman, if you could answer the question regarding the primer bulb I may be able to further help.

Also, does it run OK when you back off the throttle?

The bad coil is a possibility but I still lean towards a fuel issue.

Posted

I had the same symptoms and it turned out to be a cracked coils. Usually occurred about 15-30 mins after starting. This was on an old Johnson 6 hp that I was using as a kicker.

Posted

if it only happens AFTER the coil has heated up (10 mins or so) then almost certainly a coil issue... could also just be a faulty plug .. but I am definitely guessing you are dropping from 2 cylinders to one ... and back up to two .... fix it soon (realtively easy to replace a coil) or risk breaking a push rod....nasty fix

  • 1 month later...
Posted (edited)

I have a 9.9 evinrude that does the same thing.

if it does it again shut the engine off.

pull the spark plugs out to see if there is a piece of carbon in the gap of the plug.

mine is always in the top plug.

Edited by skeeter
Posted

I have a 15 hp Evinrude, cira 1985, which started, when running down the lake at high speed (approx 10-15 minutes time), of loosing all power - continuing to run, but only at 1/2 speed. The motor then surges - ie a couple of minutes of no power then a 1/2 minute of high speed power.... I have had the carb cleaned and disposed of all fuels, drained hoses, etc and have started using a fuel additive (Sea Foam), but to no avail. I'm open to suggestions on what to look for in correcting this problem. It has been in a repair shop, but they keep saying it is an ethanol problem. Is there a hose or something between the carb and the cylinder that could be partially blocked? I'm open to suggestions .. comments appreciated.

Thank you.

POWER PAK Losing spark on 1 cyl easy fix

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