1979 johnson 115 low power

[davidmammoth]

thanks in advance for the help. I just bought a used boat and motor and I drained out the old gas, changed the spark plugs and gapped them to .040. Took it out on the water and it idled fine. I then proceded to wide open throttle and it had very little power. It only went up to 2500 rpm. Also it wouldn't get up on plane. I then removed and inspected the fuel pump and filter screen and they looked fine. Checked compression and found them to be 120 115 115 95, I checked to see if I had spark and I did. Also i noticed 2 of the 4 plugs were wet and black the others were dry and normal. Please can someone help me. What steps should I take next. Out of the water hooked up to the garden hose, The engine gets up to rpm but with some hesitation at times . Please anyone. thanks...

 

[walleyehed]

Re: 1979 johnson 115 low power

Don't run that sucker past 2000RPM out of the water!!!!!!<br /> You have 2 dry plugs because you aren't getting fuel to those cylinders...sounds like a carb cleaning and kit time. the small jet orfices are prone to varnish if not properly stored.....

 

[bossee]

Re: 1979 johnson 115 low power

It only went up to 2500 rpm<br />------------<br />Did any alarm (lamp and or sound) go on?<br />On many outboards there is a revlimit that jumps in at around 2000-3000 rpm and limit the rpm to a preset value. Alarms can go on for various reasons like: overheat (bad cooling), low oil level or pressure etc. <br />Overheat alarms can be because of bad impeller (in waterpump), stuck thermostat, clogged cooling channels, a defect overheat sensor etc.<br /><br />But in your case it seems you get no fuel to at least two carburators/cylinders.<br /><br />Unless You know when the impeller was last changed to a new that is probably high on the to do list in the future. Probably change gearcase oil also if you do not know when that was done last. A tune up at an outboard service center is probably a good thing to do.<br /><br />/Bo

 

[davidmammoth]

Re: 1979 johnson 115 low power

Thank you for the reply. I am going to get a kit for the carbs and go that route. Will keep you posted on the results. Again, I really appreciate the replies.

 

[davidmammoth]

Re: 1979 johnson 115 low power

Also, there were no alarms of any kind. Limiters, lights, or sounds. Thank you.

 

[davidmammoth]

Re: 1979 johnson 115 low power

Hello.. Thanks again for the advice.. I double checked the ignition system and found that I was no longer getting spark on half the engine. I tested the engine with a known good power pack on that half on the engine, it worked great. I took it out on the water today it it had plenty of power. Lots of go fast!!!! Thank you all for your help!!!!!!!