2002 115hp saltwater series 2 stroke. No plane since service, and starter issue.

[BruceAnn]

Hello!
In searching for some info about my motor I came across this forum as there seems to be a fair bit of knowledge about my particular motor.
I have a Mercury 115 2 stroke saltwater approx 2002. It is the 2+2 displacement on demand setup that brings in 2nd pair of cylinders at around 1800rpm. I've had the boat/motor for 6 or 7 years during which it's done about 100 hours and no problems at all in that time. Last month I had it serviced ready for summer and took it out on the water last week for the first time since servicing.
It has developed a problem. There isn't enough power to plane. Motor is running smooth and starts easily but it's as if the 2nd pair of cylinders never come on, and the motor just struggles along on 2 cylinders. AS you would expect I took it back to the service shop and they looked at it and couldn't find anything wrong.. all cylinders running, spark, etc but here's the catch.. this place has no access to any lake and can only test in a tank. They are unable to test in gear at speeds high enough to bring in all 4 cylinders.
Their only suggestion was to wash out the carbs, a four hour job @ $99 /hr only to give it back to me untested. I declined, opting instead to take it 2 hrs out of town to a Mercury service shop that has on-water test facility (can't get booking till 2nd Jan 2103). I managed to get a refund of half the labor cost of the original service, since in my view I had taken in a functioning motor and got it back unusable. The guy said the service could do nothing to introduce such an issue and suggested it must be coincidence that is has appeared between using before and after service. That's possible I suppose. Not sure I'll ever know.
Anyway, the purpose of my post is to ask whether anyone here knows these motors well enough to suggest what the actual problem could be? Is this sort of issue common with these 2+2 setups, or is it more likely the service mechanic has busted it somehow? Could something as simple as forgetting to prime cause this effect.
I have another less serious problem also. The starter motor sometimes does not engage and just sits there whirring. If I open the cover and tap the head of the starter with a wrench it then works. Obviously something is sticking but again I'm looking for suggestions what to do; new starter needed, or just some lubricant in the right place? I did ask the mechanic to look at this also but he couldn't reproduce it and "inspected/lubricated" the relevant bits. It had no effect.. issue reoccurred almost immediately on next use.
Sorry for long post.

 

[Silvertip]

Re: 2002 115hp saltwater series 2 stroke. No plane since service, and starter issue.

Let's do the starter issue first. The small gear on the end of the starter motor shaft must rise up when the starter is engaged. In your case it is not doing that for any number of reasons -- all of which are simple to check and correct. 1) See the spiral grooves in the motor shaft?? If those grooves are all gunked up the bendix (with the gear on it) cannot spin up the shaft. Use any degreaser (brake cleaner or even alcohol) to clean those grooves. Then use a very light lubricant (a silicone spray for example) to lubricate the shaft. If that doesn't work then 2) Use a voltmeter to measure battery voltage while you have someone crank the engine. If voltage drops below 10.5 volts the battery needs to be charged. The bendix needs the starter to really rev up quickly in order to spin up the shaft. Low voltage prevents that from happening. 3) Tapping the starter may indicate there is a loose or corroded connection on the starter or the solenoid. Check, clean and retighten all battery cable connections. 4) There is black plastic/rubber cup shaped device at the bottom of the bendix. Make sure that is clean as if it sticks to the motor housing it can prevent the bendix from rising.

As for the two cylinders not coming on-line it may be because the carbs are due for a cleaning. You didn't indicate what the "service" was that the shop did for you but it would typically involve changing lower unit lube, perhaps changing spark plugs, and possibly adjusting idle speed and mixture, timing and doing a link & sync. If he messed with the carburetor linkage while doing timing and/or link & sync, yes -- he may very well have been at fault. Spark on those cylinders will be present at all times whether or not the carbs are providing fuel under 1800 rpm.

 

[BruceAnn]

Re: 2002 115hp saltwater series 2 stroke. No plane since service, and starter issue.

Thanks Silvertip,
The service invoice says..
Drain/replace gearbox oil and drain plug washers
Remove propeller, lube shaft and refit prop
Remove gearbox and replace waterpump impeller, refit gearbox and check shift operation
Remove, check and replace spark plugs
Compression check OK
Spark check OK
Remove and replace fuel inline filter
Remove and replace water separating fuel filter
Remove, check and refit thermostat - ok - new gasket
Replace missing vent in oil resevoir
Run and check motor
Check throttle and shift operation
Check water flow and cooling system operation
Apply corrosion protection

Parts..
Fule filter - inline -lrg
Gear oil
Drain plug washers
Vent Assy
Fuel filter - water separator
Impeller
Gasket
Corrosion Guard
4 x spark plug

As mentioned, I do have it booked into another service shop (with on-water testing) so unless I can locate some simple and easy to fix explanation for this sudden issue then I'll go ahead with that. I suspect it may well be due for carb flush as that has never been done to my knowledge. In the meantime I am arming myself with knowledge so that I can talk intelligently with the mechanic and understand what he tells me. I'll definitely have a look at the starter bendix and wiring as you suggest.