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I have 2006, Mercury 3.5 hp 4 stroke engine. And there is no spark.

S

Sporbert1

New member
I have replaced the spark plug, ignighter and fly wheel after many conversations with Mercury Help line and with there suggestion this engine still does not developed any spark. I have purchased several ifnighter with no success the mercury Help said they could not help with any further suggestions. I cleaned the coil connection and the ground connection to the block. Removed the spark plug and hand pull cord and spun the motor uith a angle drill and no spark. Basic I have replaced all parts with oem parts and it don't work if any one knows the solution to this problem or has an experienced I would greatly appreciate the help!
 
I'll add a thought or two..... Since you've changed a lot of parts and worked with Mercury, I assume you checked some of the other possible causes? Did you check all the usual safeties to prevent starting ??? Kill switch /wiring, Neutral safety, throttle position safety?? I'm just thinking that the motor may not "want" to start do to some other reason than the bad parts ?? Other than that I'd get the manual out and do a peak/ dvm voltage check starting from the coils when cranked and go on from there .... Perhaps you have already done these checks ..
 
this is not a sophisticated control circuit there is no lock out safety switches there a black ground, high voltage plug wire and a tan shutdown wire that goes through the safety lanyard. I checked the voltage at the tan wire (that was disconnected) while cranking with a angle drill clockwise on the fly wheel (plug removed) it fluctuated approximately 2.8 to 3.4 vdc . I have tested three igniters the resistance to ground the high voltage lead to ground varied from 6.9 K ohms to 7.2 K ohms. the tech support from Mercury originally said the resistance should be between10.7 and 15.7 K ohms and said if it didn't replace the coil. they later said to remove the end spark pug connector and read directly to the wire and it should be 2.0 K it actually read 2.2 k ohms they said there was nothing wrong with the coils. The clearance between igniter and the flywheel magnets is .010 " by feeler gauge. I have cleaned all the connections to the engine bock and coil and installed lock washers to help dig into the metal and assure a positive ground. this is a basic magneto it should fire up. There is no after market application that I can find. If I can find one that will work I would buy it.
 
This a one cylininder 4 stroke engine only one spark plug. I have replaced the ignighter with three different ignighters.
 
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I spent some time looking up what I could for parts and info on your engine. The only thing I can think of is to move the coil as close as possible to the fly wheel (temporarily) so you can spin it without hitting with plug removed. Then try to spin it with the drill and see if you get a spark.
 
I remover the spark plug positioned the ignighter as close as I could .005" , spun it with a drill no spark. Also used a Tohatsu coil 3AB060410M "new style " labled on the coil MAU 6A, it looks just like the Mercury one. Resistance to ground front the high voltage to ground 6.99 K ohms sams as the Mercury, again no spark with the tan wire disconnected ( kill button).
 
Sporbert1 said:
I remover the spark plug positioned the ignighter as close as I could .005" , spun it with a drill no spark. Also used a Tohatsu coil 3AB060410M "new style " labled on the coil MAU 6A, it looks just like the Mercury one. Resistance to ground front the high voltage to ground 6.99 K ohms sams as the Mercury, again no spark with the tan wire disconnected ( kill button).
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Not the igniter/trigger - the large coil
 
there is no large coil, the there is only one component the igniter, witch is the magneto coil that creates the voltage when the magnetic field of the magnets on the flywheel passes in the proximity of the windings. The ignition charge coil is integral in the igniter. A view of this opponent can be seen by Google of "89813T58"
 
I had to do some digging to see "what model" you have. This is nothing like Merc ever built before or after (and actually it looks to be a Tohatsu build and not Merc at all).

You have basically replaced the very few components that could be bad. You said you changed the flywheel so unless the magnets were bad on the new one that shouldn't be the problem.

The "it does everything coil" on these provides the power for the sparkplug, the trigger and acts as the cdi/switchbox on just about every other model. You note that you have gone through a couple of these.

And as you have stated this is not a very complex system and you have changed all the components that could be bad.

The only thing I can't see that you have listed as having tried is isolating the stop circuit. Coming from the igniter you have the ground wire (with the ring connector), the spark plug lead and the stop circuit (which looks to be a bullet connector coming from the igniter).

Have you disconnected that bullet and isolated it so that it is not in contact with the block?

If you have then I am out of ideas unless the "new flywheel" is defective and your old one was as well. You say the (coil) checks good and there just isn't anything else left..
 
galamb said:
If you have then I am out of ideas unless the "new flywheel" is defective and your old one was as well. You say the (coil) checks good and there just isn't anything else left..
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X2 Wish I could think of something else to help. I do remember many years ago when I worked for Sears and did some motor repair work that there was a "tester" for the magneto coils. IIRC it was little more than a AC transformer. You would pull the flywheel and place the transformer next to the pick up coil and it would generate a spark off the lead. Perhaps you can find / google bench magnito testing and try to prove the unit works on the bench ??? Good Luck and be sure to let us know the outcome - good or bad.
 
you are absolutely correct this is Tohatsu design in fact I believe all outboards sold under the Mercury Logo (less than 30 HP) are made and designed by Tohatsu. when checking for spark I have always disconnected that bullet kill plug connector. My gut feeling is this system has a fatal flaw. and in about 2009 they (Tohatsu) changed the flywheel and igniter. the part # are different and when I can pictures and sketches they definitely appear different and the ohms resistance of (do every thing coil comp) igniter. The real questions is will these new components back fit. I will contact Mercury Help but I'm not sure they will divulge that answer!! Or maybe only Tohasu knows. the first thing they will probably say is this is 10 year old motor we have no obligation.
 
Sportbert1.. did you every figure out what it was? I have a Mercury 3.5hp and also have replaced ever part possible. I could have bought a new one for how much I have spend on this motor. I too cannot get a spark and all of the numbers that you posted for: "fly wheel (plug removed) it fluctuated approximately 2.8 to 3.4 vdc. Igniters the resistance to ground the high voltage lead to ground varied from 6.9 K ohms to 7.2 K ohms. the tech support from Mercury originally said the resistance should be between10.7 and 15.7 K ohms and said if it didn't replace the coil. they later said to remove the end spark pug connector and read directly to the wire and it should be 2.0 K it actually read 2.2 k ohms". I too got all of the same numbers and cannot get a spark. I know that was a post from years ago, but I am dealing with the same thing right now. Hope you can help me on this?
 
ew371pla said:
Sportbert1.. did you every figure out what it was? I have a Mercury 3.5hp and also have replaced ever part possible. I could have bought a new one for how much I have spend on this motor. I too cannot get a spark and all of the numbers that you posted for: "fly wheel (plug removed) it fluctuated approximately 2.8 to 3.4 vdc. Igniters the resistance to ground the high voltage lead to ground varied from 6.9 K ohms to 7.2 K ohms. the tech support from Mercury originally said the resistance should be between10.7 and 15.7 K ohms and said if it didn't replace the coil. they later said to remove the end spark pug connector and read directly to the wire and it should be 2.0 K it actually read 2.2 k ohms". I too got all of the same numbers and cannot get a spark. I know that was a post from years ago, but I am dealing with the same thing right now. Hope you can help me on this?
Click to expand...
Any insight on a solution?
 
cstafford507 said:
Any insight on a solution?
Click to expand...
I still have not figured it out. It is sitting in my garage. The only thing that I can think is that I somehow have the wrong ignition. I have crossed referenced the ignition that I have with Mercury and online sources, and as far as I can tell, I have the right one. It is a simple system and makes no sense why I would not have a spark. I have a new ignition, new spark plug, new fly wheel, new kill switch. The gap between the flywheel and the ignition is set correctly. I even moved it a couple thousandths closer and still no spark.
???
Thoughts?
Eric
 
ew371pla said:
Sportbert1.. did you every figure out what it was? I have a Mercury 3.5hp and also have replaced ever part possible. I could have bought a new one for how much I have spend on this motor. I too cannot get a spark and all of the numbers that you posted for: "fly wheel (plug removed) it fluctuated approximately 2.8 to 3.4 vdc. Igniters the resistance to ground the high voltage lead to ground varied from 6.9 K ohms to 7.2 K ohms. the tech support from Mercury originally said the resistance should be between10.7 and 15.7 K ohms and said if it didn't replace the coil. they later said to remove the end spark pug connector and read directly to the wire and it should be 2.0 K it actually read 2.2 k ohms". I too got all of the same numbers and cannot get a spark. I know that was a post from years ago, but I am dealing with the same thing right now. Hope you can help me on this?
Click to expand...
I have exactly the same problem. Ordered a new igniter, which didn't fix the problem. The igniter consists of a primary coil & a secondary (high voltage) coil. My secondary coil resistance is 14K ohms, which is per the service manual. But when I try to measure primary coil resistance, between kill switch connector and igniter frame, I see open circuit - on both old & new igniters. The service manual does not mention primary coil - but there has to be one - it's that coil which is "excited" by the magnet passing, creating a low voltage in that coil - which induces a high voltage in the secondary coil. The primary coil should have only between 3 and 7 ohms resistance - but I see open circuit, and don't understand why.
BTW - how do you connect a drill to the flywheel?
 
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