Crazy Merc problem

[JoshKeller84]

I've been working on this motor since last november, and still cant get it. its a 1988 8 hp merc, tiller. The carbs have been soaked and cleaned at least 10 times. New gaskets, new reed valves, new spark plugs. Still does it.

Compression is 90 lbs on each cylinder.

It idles poorly, if at all. Accelerates very poorly. Once it breaks over and gets up to around 10 - 12 mph (it takes about 10 seconds), i can literally feel the top cylinder kick in, and away it goes, running as it should to around 19 mph. It will BARELY idle on just the top cylinder if the fast idle is maxed and I help it along a little by moving the timing lever. Put the bottom plug wire on, and it takes off like it should. Reverse the process, and the top cylinder has no effect on the idleing speed.

Removing the plugs and turning the motor over and both holes have gas mist coming out. i will say that I removed the plug wire with my bare hands on the top cylinder and felt absolutely nothing in terms of shock.

any ideas??

 

[achris]

Re: Crazy Merc problem

Swap the coils and see if the fault follows the coil or not... Have you checked the crankshaft top seal?

 

[JoshKeller84]

Re: Crazy Merc problem

I swapped the coils and it still remained on the top cylinder. I would assume its listed as the "crank case upper oil seal?" I assume I need to pull the flywheel and take a look?

 

[achris]

Re: Crazy Merc problem

Listed as "Oil seal, upper" (part # 26-12567 1), and yep, flywheel off to access it.

Chris..........

 

[CharlieB]

Re: Crazy Merc problem

Pulling a plug wire and not getting bit causes me to wonder if the ignition is firing that coil adequately. A Spark Test using an adjustable gap tester set to 1/2 to 7/16 inch should show a hot blue snap necessary for reliable operation, any less is cause for further testing to determine the source of the problem.

I would wait on the crank seal until you test the ignition completely, you can always go after the seal after making sure the ignition is functioning correctly.

 

[achris]

Re: Crazy Merc problem

Pulling a plug wire and not getting bit causes me to wonder if the ignition is firing that coil adequately. A Spark Test using an adjustable gap tester set to 1/2 to 7/16 inch should show a hot blue snap necessary for reliable operation, any less is cause for further testing to determine the source of the problem.

I would wait on the crank seal until you test the ignition completely, you can always go after the seal after making sure the ignition is functioning correctly.

Agree.... Check the easiest things first...