Mercury 50hp 3 cylinder - Fuel, Spark, 120psi compression - No Start

[bigshrimpin]

Hey guys - I'm hoping that someone can point me in the right direction . . . I have a clymer manual and it's no help. Service manual is in the mail.

I recently bought a 1989 Mercury 50hp that's in beautiful shape. The trigger and stator were bad . . . after I replaced them the motor has spark in all 3 cylinders (when I ground the plugs to the block).

Tested compression = 120psi in all 3 cylinders

replaced fuel pump, filter, cleaned carbs . . . fuel system is supplying fuel to all 3 cylinders.
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When I put the plugs (New plugs = NGK BU8H) back into the motor . . . I swear there's no spark.

The motor doesn't fire at all. Doesn't kick over . . . no smoke . . . nothing.
even with a fully charged battery and fresh fuel. I even dipped the plugs in fuel and put them back in the motor.

What am I missing?

 

[tashasdaddy]

Re: Mercury 50hp 3 cylinder - Fuel, Spark, 120psi compression - No Start

1st you need a real spark tester. can be bought at auto parts store, here's an example. http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=96077

you can also go to maxrules.com clik technical assistance, to get info to check your electrical.

 

[alphamax]

Re: Mercury 50hp 3 cylinder - Fuel, Spark, 120psi compression - No Start

Have check for exact timing with strobe?

 

[bigshrimpin]

Re: Mercury 50hp 3 cylinder - Fuel, Spark, 120psi compression - No Start

Thanks for the link to MaxRules . . . It got me focused on weak/no spark and getting more juice to the starter so the flywheel could move faster.

I replaced the starter solenoid and the battery harness. I put some fuel in one hole and pulled the other two plugs (hoping that the motor would spin fast enough to create spark) The motor started right up on one cylinder. Repeated on 2 and 3. Then I put all the plugs back in and the motor fired right up. Problem solved . . . . idles perfectly and starts immediately.