79 115hp evinrude will not accelerate

mnessman

Seaman
Joined
May 12, 2008
Messages
62
I have a 79 115hp evinrude, it starts and idles fine. When I try to accelerate it starts to do good then falls on its face and will go only about 5-10 mph at full throttle. I had this problem before and the mechanic said I had trash in the fuel system. I have a new fuel filter and have checked all fuel system components, I have replaced the spark plugs. I don't know what else to check.


about 2 years ago the carbs were rebuilt along with a new fuel pump and all new lines under the cowl, they also replaced 1 coil and a power pack. 1 of the coils that is on the motor is sticky, i have a 79 100 hp Johnson and since it has already had 1 coiled replaced i swapped the coils to see if that will improve the running. before I replaced the coil and after when the motor is at idle it misfires every once in awhile. I have not taken the boat out since cleaning the fuel system and changing the coil. and yes the gas around here does have ethanol and no I have not used any gas treatment. Another not that might be useful is last summer my son took the boat out and the plug came out. the motor never went totally under water but the water was up to the cowl. When I got the boat home I used fresh gas and was able to start the motor and I let it run for a while to flush any water that might possible have gotten into the motor and also lubricated the internal motor good. I have checked the compression and all 4 cylinders are running around 150psi.
 

danoutbard

Petty Officer 3rd Class
Joined
Nov 18, 2011
Messages
87
Re: 79 115hp evinrude will not accelerate

Check for spark, get a spark gap tester or built one. A good spark should jump between two node a 7/16" air gap and be a solid blue. These V4 can easily start & run on three cyl.
 

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
13,638
Re: 79 115hp evinrude will not accelerate

You are saying you haven't used the boat since when? last year? this year? How old is the gas? My guess is the carbs are gummed up and need to taken apart and cleaned.
 

danoutbard

Petty Officer 3rd Class
Joined
Nov 18, 2011
Messages
87
Re: 79 115hp evinrude will not accelerate

Good point,i'd try that for shure..

You are saying you haven't used the boat since when? last year? this year? How old is the gas? My guess is the carbs are gummed up and need to taken apart and cleaned.
 
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