Mercury KE-7 potential issues

[green-thumbs]

What do you know of your KE 7’s history? Did you acquire it as a running motor?
Many old outboards were put away for a reason and many have been worked on by the less skilled,
Assume Nothing and Double Check Everything including you own work. An old time gas station mechanic told me “If it has ignition, carburetion and compression it has to run”
A motor that starts, runs and
quits suggests it is getting enough fuel ai mixture to start but not enough to keep
running. Try another carburetor, fuel filter and
clean out fuel line. Tank
may not be as clean as you thing it is. Easy was to check
carburetor is to swap in a known to be good carb of same
make and model. Same with spark plugs.
Your first Merc will either sour you on the breed or tempt
you into another,
Good Luck

[Waunnaboat]

I was on a trip and was not able to look into it, but now that I am back I am guessing that the issue lies in the coils and/or condensers because the spark was very weak with brand new J8C spark plugs (I know that may not be right, but I just needed to check for spark in a hurry).  Being that it can best be described as a “Frankenstein motor”, and I did not pay much for it, I think I will let it go and get a better example of a KG-7 that will give me less trouble. I find the KE-7 lineage of motors to be very interesting, so I doubt that I will give up on the whole Mercury brand for a while.

"Outboards seem to multiply exponentially..........I find that for every finished project, there are two more waiting to be completed."

[green-thumbs]

A Parts Manual and a junk motor to take apart may be low cost high return investment
if you turn Green,
Louis

t

[Waunnaboat]

green-thumbs wrote:

A Parts Manual and a junk motor to take apart may be low cost high return investment
if you turn Green,
Louis

t

I’ll definitely think about that.  I was actually able to get it to run well with the prop off in the test tank by starting it at full throtle.  I don’t know what is occurring inside there that causes a need for weird starting, but it is running well and pumping water, so it is A OK in my book for the time being.  Time will tell weather or not it runs well tomorrow on a lake.

"Outboards seem to multiply exponentially..........I find that for every finished project, there are two more waiting to be completed."

[green-thumbs]

Spark advance and carburetor butterfly opening are synchronized. It may be worth checking of carb is properly
assembled… they can be misassembled… guess why I know.
Louis

[Waunnaboat]

green-thumbs wrote:

Spark advance and carburetor butterfly opening are synchronized. It may be worth checking of carb is properly
assembled… they can be misassembled… guess why I know.
Louis

I did look at that, and the butterfly was opening as advance lever advanced, which I assume would be right.   I tried a few more times (about 100 good pulls at various speeds and with choke on and off at various times) and was not able to get it to pop, so I don’t quite know what is up with it.  Sometimes it starts, and other times it doesn’t.  I will try getting a better example of a 10+ mercury next year, but considering that this motor has so many (somewhat) mismatched parts, I do not think it is worth the time for me to fix it.

"Outboards seem to multiply exponentially..........I find that for every finished project, there are two more waiting to be completed."

[outbdnut2]

When I ran my KE-7 on a minimost hydroplane, it would lose some power after a while.  Putting a fuel pump between the on-board tank and the carb cured it.  Somehow the gravity feed wasn’t getting enough fuel to it for hydroplane use – it worked fine on a 14′ aluminum boat without the pump.

Dave

[billw]

My KE7 drove me crazy with misfire, for a long time. It would run good for awhile, then start to drop a cylinder. Everything was new. I finally figured out that the old bedding compound on the pads under the Bendix coils had a very, very high meg-ohm level, resistance. I just stuck my meter leads across the pads and got a reading. I cleaned and cleaned them until I no longer got a reading on my ohm meter and it has run like the wind and idled right down nicely, ever since.ever since. Almost OMC-like run quality.

There was also a bulletin issued once, that said that if you were running a green top on a heavier boat, it might be necessary to back the throttle off until the engine ran at its highest RPM, because basically, the ignition could over-advance on a heavy boat and cause internal engine damage. Stupid design, but true. I had this happen to ME, with a KG4. It struck me that the OPs’s description of the original problem sounded kind of like this, especially when he said “it ran backwards for a minute.”

Long live American manufacturing!

[seakaye12]

billw wrote:

My KE7 drove me crazy with misfire, for a long time. It would run good for awhile, then start to drop a cylinder. Everything was new. I finally figured out that the old bedding compound on the pads under the Bendix coils had a very, very high meg-ohm level, resistance. I just stuck my meter leads across the pads and got a reading. I cleaned and cleaned them until I no longer got a reading on my ohm meter and it has run like the wind and idled right down nicely, ever since.ever since. Almost OMC-like run quality.

There was also a bulletin issued once, that said that if you were running a green top on a heavier boat, it might be necessary to back the throttle off until the engine ran at its highest RPM, because basically, the ignition could over-advance on a heavy boat and cause internal engine damage. Stupid design, but true. I had this happen to ME, with a KG4. It struck me that the OPs’s description of the original problem sounded kind of like this, especially when he said “it ran backwards for a minute.”

Very Interesting Bill.

So….too much advance in relation to RPM?  Why wouldn’t the same thing be possible on any engine that had a link-n-synch type throttle arrangement?

[Tubs]

I struggle to understand how this motor ran backwards. The motors I have had that do run backwards, when the rotation is reversed, so is the positioning of the magneto lever. So the timing is retarded to the point the motor won’t run (backwards). Fast becomes Stop – Stop becomes Fast.

A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.

[Author]

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