Envinrude 115 1980 RPM problems

[wingman99]

Hi ....Just new here thanks for having me!!

I have a 115 envinrude 1980 outboard. I put the boat in the water for the first time. Started up fine in driveway and in the lake. First trip out I wanted to test my RPM so I could get a new prop. Took off from dock and was doing 27miles/hour at 5500rpm. There was a little throttle left. A half hour to an hour later the motor would only do 23miles/hour at 4900RPM. Full out throttle to the max point and it wanted to choke off or sputter a little with max throttle. Backed off a hair and run fine but no more speed or RPM than 4900. That continued the rest of the day. Took the boat out and put back in for another run the next day and it started where it let off the day before.4900RPM maxed. Why would it not run up at 5500rpm anymore???Why only at the first of the day first run??? Thanks if anyone can help me out!!!

 

[billy4hp]

Re: Envinrude 115 1980 RPM problems

Hi ....Just new here thanks for having me!!

I have a 115 envinrude 1980 outboard. I put the boat in the water for the first time. Started up fine in driveway and in the lake. First trip out I wanted to test my RPM so I could get a new prop. Took off from dock and was doing 27miles/hour at 5500rpm. There was a little throttle left. A half hour to an hour later the motor would only do 23miles/hour at 4900RPM. Full out throttle to the max point and it wanted to choke off or sputter a little with max throttle. Backed off a hair and run fine but no more speed or RPM than 4900. That continued the rest of the day. Took the boat out and put back in for another run the next day and it started where it let off the day before.4900RPM maxed. Why would it not run up at 5500rpm anymore???Why only at the first of the day first run??? Thanks if anyone can help me out!!!

The list of answers to your question is, well a laundry list so:

Is it overheating?
Fouled plugs
Plugged carbs
Fuel restriction
Ignition misfire / dead cylinder
Poor compression
Weak fuel pump
Bad fuel lines plugging carb

Basically you need to start at the beginning, check the engine out by first doing a compression test and make sure the engine is healthy...

Read the Top Secret threads on the first page, loads of information....

And an OEM manual is a must if you are going to do the work / troubleshooting yourself..

Good luck...

 

[tashasdaddy]

Re: Envinrude 115 1980 RPM problems

agree ^^^ http://forums.iboats.com/showthread.php?t=299680

 

[wingman99]

Re: Envinrude 115 1980 RPM problems

Thanks for the list!!!!

I did start with the fuel lines and while doing that job I pulled the plugs and think I FOUND THE PROBLEM!!!
The first plug I pulled looked like it was hit!!! Crushed in!!
Tested the piston play at top dead center and yes there is.
No other plugs were hit but other pistons had play!!

Holy !! Now where do I go ????

 

[billy4hp]

Re: Envinrude 115 1980 RPM problems

Thanks for the list!!!!

I did start with the fuel lines and while doing that job I pulled the plugs and think I FOUND THE PROBLEM!!!
The first plug I pulled looked like it was hit!!! Crushed in!!
Tested the piston play at top dead center and yes there is.
No other plugs were hit but other pistons had play!!

Holy !! Now where do I go ????

Well now you need to pull it down and find where the play is, so next step would be procuring an OEM manual if you don't have one already... Skip the SELOC or Cylmder's manual as they are too generalized IMO...

Ebay or Ken Cook are the best source for OEM manuals...

Good luck...