Throwing in the towel

[Gary H NC]

Well,My boat repair business has gone very well over the summer and have plenty of winterizing jobs scheduled for the fall.

I only had one job that i gave up on..
After many hours of research,testing and going over the shop manual and 20 some hours working on this 1991 Merc 3 cylinder 2 stroke i had to tell the owner i am at the end of my trying to get it to run.

It has great even compression,fuel and good spark.The timing is dead on but not even a sputter...
I have tested everything over and over after getting the powerpack replaced and still nothing.It had no spark when i first started

Any other guys that wrench on boats just have one that beat them.
I believe in doing the job right and being completely fair with the customer.
I even rented a trailer to get this pontoon out of the lake.

Can't win them all....

 

[mphy98]

Re: Throwing in the towel

as you well know you only need three things for a gasoline engine to run. compression, spark, and gas. The only variable is timing and amount of fuel. I would squirt a small amount of fuel into each cylinder then try to start it. if it runs, then it is carb, if not spark at the proper time would be the culprit. Is it possible you are 180 out of time?

 

[Numlaar]

Re: Throwing in the towel

havent had it on a boat motor before, but I have with my truck!

ASE master tech, and this one has me completely stumped, and I too have thrown in the towel... gonna tow it to ford and let them have a go at it...

I won't hijack and go into details, but suffice to say I can feel your pain...

My suggestion would be to do as suggested, go back to basics, check for fuel, test by putting some gas straight into the cylinders with the plugs out, put the plugs back in and give it a whirl ... if it sputters you got a fuel problem... if not, then its a spark problem... only two things it can really be if you have good compression

Good luck with it!

 

[windsors03cobra]

Re: Throwing in the towel

Yea I had to do that a POS Ford SOHC 4.0 once, what a load of rubbish that engine is.
I hate when that happens.

 

[JustJason]

Re: Throwing in the towel

I was curious as to how you made out on that, i remember the thread. I had a 9.9 last month doing the same thing. Couldn't make it even fart and I had compression/fuel/ and timed spark.
After I pulled the reed assembley out I found a dime sized hole in the block between the 2 crankcase halves. Basically my compression... and fuel/air charge was swapping spit between the 2 cylinders and not even making it up top. Took me freaking forever to find it, and I even missed it the first time I took out the reed block and stuck my eyes in there... I found it the second time. I wonder if your having a similar issue.
Kinda gives WOT a new meaning.... Waste Of Time.

 

[tashasdaddy]

Re: Throwing in the towel

Gary i had one about 3 months ago, that finally stumped me. even with help from the Johnson forum, and 3 other local mechanics, we could not get it to run right.

i have been fighting one for 3 weeks, yesterday, i started it. the stupid thing ran fine. i did nothing to it yesterday. it just decide it was time to run correctly.

 

[Gary H NC]

Re: Throwing in the towel

Thanks Guys,

Yes,I tried the fuel straight down the carbs,checked timing,tried several different attempts while advancing the timing base.Then set timing per the book.
Nothing..no pop or anything.Compression 105 on every cylinder.
The reeds came to mind too.

I hope the dealer can figure it out without sticking it to the owner.

I think i may refuse to take in any non-running Merc outboards in the future.

 

[Gary H NC]

Re: Throwing in the towel

Gary i had one about 3 months ago, that finally stumped me. even with help from the Johnson forum, and 3 other local mechanics, we could not get it to run right.

i have been fighting one for 3 weeks, yesterday, i started it. the stupid thing ran fine. i did nothing to it yesterday. it just decide it was time to run correctly.

I hear ya TD...wish this one would decide to run.
I have worked in for the last few weeks off and on.

Hooking it up this morning and to the shop it goes...

 

[QC]

Re: Throwing in the towel

You should probably put muffs on and crank her over in the Dealer's parking lot; she'll probably fire there . . .

 

[jonesg]

Re: Throwing in the towel

Thanks Guys,

Yes,I tried the fuel straight down the carbs,checked timing,tried several different attempts while advancing the timing base.Then set timing per the book.
Nothing..no pop or anything.Compression 105 on every cylinder.
The reeds came to mind too.

I hope the dealer can figure it out without sticking it to the owner.

I think i may refuse to take in any non-running Merc outboards in the future.

Try injecting fuel directly into the cyl thru the sparkplug hole, spraying it into the carb could still miss the problem.

I would also try removing plugs and blip it over good with the starter in case its flooded, could be water in the case too putting out the fire.

 

[JB]

Re: Throwing in the towel

as you well know you only need three things for a gasoline engine to run. compression, spark, and gas. The only variable is timing and amount of fuel.

Well, not quite, Murph. You have to get the gas, mixed with an appropriate amount of air, into the combustion chamber.

In a 2 stroke this is the job of the piston pumping action, sucking air through the carb(s) and picking up a correct amount of gas there, then pushing the fuel/air mix through the bypass into the combustion chamber.

For short, I call that whole pumping process scavenging.

Failures in scavenging are pretty rare, and because most of us have never encountered it before it often baffles us.

I suggest that you investigate the scavenging in that Merc, Gary. The most common failures are in carb gaskets, reed block gaskets, reeds, bypass cover gaskets and crank seals.

 

[Gary H NC]

Re: Throwing in the towel

I think JB is on the right track and is thinking the same way i am.
I tried all the tricks of spraying fuel in the carbs and spark plug holes,ect..
Nothing got it to fire at all.

The dealer can have the job. I have at least 15 or more hours into that engine and i am done.
I got a feeling the dealer will find a reed problem or something along that line..

 

[rolmops]

Re: Throwing in the towel

I was about to throw in the towel on my merc.The solution turned out to be ridiculously simple.Vapor lock in the fuel pump.

 

[corm]

Re: Throwing in the towel

Hi,

If it was a 50 or 60 HP did you pull the exhaust plate to see if it was carbon choked. I have seen that on pontoon engines many times. Hard to catch the first time you see it.

I had an old 3 hp evey ducktwin beat me yrs ago. Did everything to it, but what it wanted. It never ran. I was not the only one who could not fix it. Two other real good wrenches worked on it. They both said WTH. They were so simple they always ran, but not that one. I even hooked up an electric motor to it to turn the engine over to seat the rings. Now that was desperate, reaching for anything to make it work.

 

[Gary H NC]

Re: Throwing in the towel

The powerhead was supposed to have been just rebuilt and had less than 10 hours on it since.
It has to be something internal.Splitting it open was more than i wanted to get into with it.