I'm new to boating, but somewhat experienced with cars. A couple years ago I bought a 17' boat with a 115 merc with only 630 hours on it. I bought it in mid-fall and I let it sit over the winter without doing much to it, then ran it a bunch last summer. I was probably out in it twice a week for wakeboarding and it was great. I had a 15 pitch prop to keep the revs up during wakeboarding ~23 mph and the performance was crisp, it shot out of the hole with 3 people in the boat and a boarder on the back and with 2 guys in it, would do 45mph. It has single barrel carbs with the distributorless thunderbolt ignition (2 switchboxes).
It has always had trouble idling, I usually start it in neutral with throttle, pull it back quickly to engage the forward gear and then quickly forward to get it some throttle before it dies. This season that problem is still there. Also, when a boarder falls and I back off to 1/2 throttle, the engine usually wants to die. It usually catches itself if I back off the throttle all the way (fuel delivery/float level issue?)
At the end of last year I attempted winterizing it but spraying storage seal into it as it shut down and then put some into the combustion chambers by pulling the plugs, I also did the leg oil. This year, it has been running with less power. It used to do 45 mph with the torquer prop, but now it can only get to 40 at best and it takes much longer to plane unless it's trimmed just right.
Things I am contemplating:
- de-carb? Would a carboned engine have reduced performance? I think that's an obvious answer... but just to confirm
- timing sync. I have never done this, but I didn't think it would work itself out of sync over the winter.
- Should the impeller be replaced? The tattle-tale shoots out... not super forcefully at idle, but it's also not a trickle - it's definitely a continuous stream.
- I did a compression test and 1-5 were all within 5 lbs, I couldn't get the gauge into #6... BUT I did an idle test where I pulled each plug wire one-by-one and the engine lowered it's speed everytime, so #6 is firing.. just not sure of the compression though.
- When I had them out, the plugs looked ok, but they're center fire ones and I'm not totally sure what I was looking for. They were wet, if that means anything, but not discolored like they were carboned up.
- I'm considering pulling the fuel pump to look at it, as I've read that pin hole leaks can cause wet fouling and stalling at idle speeds (which is what I have) and then stalling at 1/2 throttle after running at full throttle issue makes me think that maybe the pump isn't delivering enough gas.
- just recently I did the primer bulb/visible fuel line from transom to the motor and put hose clamps on all of the fuel lines on the tank side of the pump under the engine cover. Previously the lines were held on with zap straps...
but that didn't help at all, no effect there.
It pulls smooth, it's just low on power compared to last year and I'm scared I've wrecked something... but I don't know what would cause this. I could start throwing fuel pumps, carb rebuilds
Thanks in advance! I have already got a ton of information from these forums, I appreciate everyone's input.
It has always had trouble idling, I usually start it in neutral with throttle, pull it back quickly to engage the forward gear and then quickly forward to get it some throttle before it dies. This season that problem is still there. Also, when a boarder falls and I back off to 1/2 throttle, the engine usually wants to die. It usually catches itself if I back off the throttle all the way (fuel delivery/float level issue?)
At the end of last year I attempted winterizing it but spraying storage seal into it as it shut down and then put some into the combustion chambers by pulling the plugs, I also did the leg oil. This year, it has been running with less power. It used to do 45 mph with the torquer prop, but now it can only get to 40 at best and it takes much longer to plane unless it's trimmed just right.
Things I am contemplating:
- de-carb? Would a carboned engine have reduced performance? I think that's an obvious answer... but just to confirm
- timing sync. I have never done this, but I didn't think it would work itself out of sync over the winter.
- Should the impeller be replaced? The tattle-tale shoots out... not super forcefully at idle, but it's also not a trickle - it's definitely a continuous stream.
- I did a compression test and 1-5 were all within 5 lbs, I couldn't get the gauge into #6... BUT I did an idle test where I pulled each plug wire one-by-one and the engine lowered it's speed everytime, so #6 is firing.. just not sure of the compression though.
- When I had them out, the plugs looked ok, but they're center fire ones and I'm not totally sure what I was looking for. They were wet, if that means anything, but not discolored like they were carboned up.
- I'm considering pulling the fuel pump to look at it, as I've read that pin hole leaks can cause wet fouling and stalling at idle speeds (which is what I have) and then stalling at 1/2 throttle after running at full throttle issue makes me think that maybe the pump isn't delivering enough gas.
- just recently I did the primer bulb/visible fuel line from transom to the motor and put hose clamps on all of the fuel lines on the tank side of the pump under the engine cover. Previously the lines were held on with zap straps...
but that didn't help at all, no effect there.It pulls smooth, it's just low on power compared to last year and I'm scared I've wrecked something... but I don't know what would cause this. I could start throwing fuel pumps, carb rebuilds
Thanks in advance! I have already got a ton of information from these forums, I appreciate everyone's input.
