Mercury KE-7 potential issues

[Waunnaboat]

Hello.  I just got a mercury Ke-7 running the other day, and when I started it on the water it ran great for a few hundred yards at what sounded like full throttle at exactly the “fast” position, but when I tried to accelerate further in case it was not fully throttled, it cut out, started to go backwards for a few seconds, and then stopped.  I got it to run for a few seconds a bit later, but I am not sure what the issue is.  The spark plugs are a bit older than I would like, so possibly this is the issue?  the only other possibilities I can think of would be something with the carb.

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

[Sam M.]

I would check if all of the linkages related to the timing are properly tensioned, as I would think the timing for running clockwise would be different to counterclockwise.  Also, if this motor has a rubber water pump impeller, it would be a good idea to check if any vanes flipped backwards.  Personally, I think spark plus are thought to be the culprit of an issue waaaaay more often then they actually are the issue, so if I were you, I’d first look elsewhere for the cause of the problem.

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Waunnaboat

[PM T2]

In my tiny little mind, there are a few “rule of thumb” things to do with those green tank Mercs.

One is look at the coils and power test them on a Merc-O-tronic or Stevens coil tester. If the results are the least bit unfavorable, junk the coil because its only going to cause you heartache later. Sometimes there is evidence that someone has tried to repair a cracked coil with epoxy. Be very wary of using such a coil in a motor unless you enjoy being stranded somewhere.

Secondly is go through the fuel system a million percent. As in, clean the tank out. Then clean it again. Clean it about eleventy-seven more times, then clean it once more. By then it should be OK.

Same with the carb but you only have to clean it eleventy-five or so times. Or once, if you use an ultrasonic cleaner and a good detergent or solvent.

Thirdly is expect that the crankshaft oil seals are going to need to be replaced. Top and bottom. Motors that start up then seem to magically fail for no apparent reason are often the work of old seals that don’t anymore.

Hope this helps eh.

Best,
PM T2

He's livin' in his own private Idaho..... I hope to go out quietly in my sleep, like my grand-dad did..... and not screaming, like the passengers in his car...

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Sam M., Waunnaboat

[chuckw]

Did the crank shaft key shear?

[Waunnaboat]

The crank shaft key did not shear,  and I forgot to mention that I did get it to run for a second or so a bit later, but had more issues with throttling.  the fuel system and coils are fine to my knowledge, and it still seems to have compression, so I do not think it is the oil seals, but I will check that in a few days.  I will try new spark plugs and fiddle around with the carb a bit and see if that changes anything.  There could be something to be said about the timing, but I do not suspect that the impeller has a vane flipped backwards because the fellow I bought the motor fro seemed to know a LOT more about mercs than I do, which is nothing apart from my limited knowledge of this particular motor.  The spark plugs were kinda inconsistent before this, so I still think that is still the issue, but I’ll see how it goes.  Thanks for the input.

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

[outbdnut2]

Note that the KE7 models changed a bit from year to year.  I have one and got a different year KE7 for a parts motor and the magplate and flywheel are much different, and won’t interchange.

Dave

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Waunnaboat

[Waunnaboat]

I got it to run for a few seconds again after letting it sit overnight, and I think I just had it running on a mixture that was a bit rich or lean.  I will adjust the carb and get new spark plugs and I think that will do the trick.

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

[lloyd]

Bad condensers are notorious for running a few seconds and then the motor shuts down.

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Waunnaboat

[Waunnaboat]

I can see condensers being the issue.  I will check that as well.

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

[Sam M.]

Waunnaboat wrote:

The crank shaft key did not shear,  and I forgot to mention that I did get it to run for a second or so a bit later, but had more issues with throttling.  the fuel system and coils are fine to my knowledge, and it still seems to have compression, so I do not think it is the oil seals, but I will check that in a few days.  I will try new spark plugs and fiddle around with the carb a bit and see if that changes anything.  There could be something to be said about the timing, but I do not suspect that the impeller has a vane flipped backwards because the fellow I bought the motor fro seemed to know a LOT more about mercs than I do, which is nothing apart from my limited knowledge of this particular motor.  The spark plugs were kinda inconsistent before this, so I still think that is still the issue, but I’ll see how it goes.  Thanks for the input.

What I meant to say was that an impeller vane may have flipped backwards while the motor ran backwards for a few seconds, not that a flipped vane caused your running issue.  Also, while it seems I have just about the same amount of Mercury knowledge as you do, if your motor is like many OMCs and uses a roller to adjust the amount the throttle butterfly valve is open when the ignition plate is rotated, (to increase or decrease the speed of the engine) then with the cowling off, it might be a good idea to check if the roller falls of the piece it rolls along in the full throttle position.  Not sure if that makes any sense, or if that is the way it works on your Mercury.

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