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1987 Merc 115 stalls under load.

timguy

timguy

Silver Medal Contributor
Owned for 10 years. Never ever any ethanol. CDI stator and trigger in 2009. Motor started perfect, freighting 4 miles then slowed down over last 1/4 mile and quit. Pumped bulb but seemed normal anyway. Tried fuel line on kicker and it ran well all the way back to camp. Restarted 115 and ran great but stalled out again after 1 mile test. Fuel bulb hard. Seems weak spark so changed spark plugs. Motor not hot, restarted, water flow normal. Ran 1/8th mile and stalled. Back in town now but 300 miles from home. Gotta fix it or this work trip to cabin is screwed. Have a small outboard shop in town, know the owner, can use tools. What is wrong? Switch box?
 
Yes infloor tank and vent good, ran 9.9 back to landing with same hose that was feeding Merc 115.
 
YOU have to determine whether or not it is fuel starvation or loss of spark when it screws up. Remove a plug wire, stick a spare plug on it, ground it to the block and crank it over.


Jeff
 
Good spark but oil injection lines all brittle, cracked and leaking. Especially supply to metering valve. My guess now is oil starvation. Lines were fine last time I used boat in 2015. They are the clear plastic lines maybe 3/16 ".
 
Good spark but oil injection lines all brittle, cracked and leaking. Especially supply to metering valve. My guess now is oil starvation. Lines were fine last time I used boat in 2015. They are the clear plastic lines maybe 3/16 ". The hose at oil metering valve was completely severed and delivering oil directly to the area under the cowling. Eventually into the lake. Fully synthetic Amsoil.
 
How can I best determine if motor is not ruined? It ran about 20 minutes at 80% power before stopping for the forth time. Comp. is: 1-103, 2-114, 3-115, 4-117. This is with WOT. Cold engine.
 
My brother needs to use the boat to freight to another remote location on Tues next week. I am setting him up with a different prop however, the Compprop is very well warn and could crack, its about 10 years in the elements. Should the 115 fail, he would be down to a 9.9.
 
I am back at home in Duluth now, we had to scrap the earlier planned trip. The lines are new, I used 1/4" and 3/16" rubber line to replace the clear plastic stuff. Maybe Amsoil is hard on the plastic lines. The motor runs great on the garden hose. The compression test was done before the motor was repaired with the new lines and a little WD40 was added to each cylinder in order they would not be completely dry. Thx Tim
 
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