84 Mercury 115hp runs great on land, but not in water under load

[CRJDriver]

I bought a 1984 Mercury 115hp used. Swapped it onto my boat and it runs and sounds great on land with the muffs. When I put it in the water it boggs down much above a high idle. Correct prop. Had stator issues and we swapped stators with another 115 mercury (same part number). Engine had been in storage for a while.

Any ideas? I am thinking it is starving for fuel somehow or has an ignition problem.

 

[jimmbo]

Re: 84 Mercury 115hp runs great on land, but not in water under load

Mine did that when I first had it in 84. The shop had to discuss it with the Merc service rep. They fixed the issue by changing the pickup timing away from the link and sync spec. I am afraid I can't remember what they set it to, but it was 28 yrs ago

 

[canoemang]

Re: 84 Mercury 115hp runs great on land, but not in water under load

Fuel starvation and ignition could be remedied by cleaning carbs and linc n sync. Check all fuel lines for cracks and ethanol break down and rot and replace.

 

[Charlie61]

Re: 84 Mercury 115hp runs great on land, but not in water under load

had same thing mine 1983 115 inline they forgot to lockdown the cable comming in from run control it run great out of water not in.

 

[CRJDriver]

Re: 84 Mercury 115hp runs great on land, but not in water under load

I blew out the tank vent line, tightened fittings on the fuel filter and fuel lines. It still has the same problem. Pumping the primer bulb will advancing the throttle does not help.

Does this sound like dirty carbs or ignition or timing?

 

[canoemang]

Re: 84 Mercury 115hp runs great on land, but not in water under load

It will rev through the roof on muff's, no resistance/load.

clean the carbs and do a link and sync.. rebuild the fuel pump while your at it.. especially if pumping the bulb helps..

 

[ejthomp]

Re: 84 Mercury 115hp runs great on land, but not in water under load

Without knowing what "bogs down" exactly means, it is impossible to say, but seeing as you had a stator issue, timing is a likely culprit.

Time for a link and sync...

 

[oldman570]

Re: 84 Mercury 115hp runs great on land, but not in water under load

Do a spark test with a timming light to be sure all the plugs are firing. It can be done on muffs running. Hook up the +&- of the light to battery and move the pickup wire of the light from one plug to another and watch for light on each plug. You might have a bad switchbox if the stator went bad.

 

[CRJDriver]

Re: 84 Mercury 115hp runs great on land, but not in water under load

I took it to a marine mechanic friend. It turns out the timing trigger was not advancing when the throttle was pushed up. He freed it up and now it is running great!

Thanks to all!

 

[Charlie61]

Re: 84 Mercury 115hp runs great on land, but not in water under load

I took it to a marine mechanic friend. It turns out the timing trigger was not advancing when the throttle was pushed up. He freed it up and now it is running great!

Thanks to all!

glad you got your boat running but I don't know about mechanic answer