1985 Mercury 115 problems

[Dmunch]

Got a boat that was sitting for 8 years, ran it for the first time and worked well until the end of the day. It lost power at full throttle and would only run at about 2400 rpm. Runs fine out of the water and I put in new plugs. Once in the water under a load, it has now power and sputters. Got a new tank and fuel filter. Didn't help it.......Any suggestions?

 

[Chris1956]

Re: 1985 Mecury 115 problems

Re: 1985 Mecury 115 problems

Sure, Take a compression test and a spark test. If those are good, clean and rebuild the carbs. Replace the waterpump impeller and the gear oil. Now retest

 

[Dmunch]

Re: 1985 Mercury 115 problems

How do I test the compression? Do I need a tool?

 

[Dmunch]

Re: 1985 Mercury 115 problems

I found 3 wires coming from the switchbox that were rotted (plastic split, wires green and barely connected). Could this be the problem or just another problem????

 

[canoemang]

Re: 1985 Mercury 115 problems

Fix those wires and also follow the directions Chris gave..

 

[BatDaddy1887]

Re: 1985 Mercury 115 problems

Use a compression tester, pictured here. Remove one plug at a time screw in the tester, crank engine at least 5 revolutions of the flywheel, read and record the result for that cylinder. More here:

http://forums.iboats.com/boat-topic...cs/how-outboard-compression-check-277383.html

 

[Dmunch]

Re: 1985 Mercury 115 problems

Thanks for the help!

 

[jimmbo]

Re: 1985 Mercury 115 problems

Take out all the sparkplugs to do the compression test

 

[Dmunch]

Re: 1985 Mercury 115 problems

compression is 91-93 on all carbs and all have spark. I'm going to rebuild the carbs and fuel pump this weekend and see if that works.