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Tohatsu mfs6c will not start

J

jrib

New member
Have 2013 sailpro it will try to run slowly 2 or 3 seconds or so and stop.
Motor looks new cranked it before I bought it last month.
It has spark getting fuel.
Oil is between the marks.
Plug looks good but have changed it 4 times anyway.
Put on new carb no change.
New fuel pump no change.
Disable kill switch no change.
Been trying to get it worked out for 3 weeks.
It did start running about 4 times after many many pulls.
When it did start each time I would run it for 15 to 20 min at all
speeds including slowest idle and top speed it ran great and
when I stopped it no more start that day no matter how many trys.
It has not started again past week but it will run slowly a few seconds
and stop.
This my first 4 stroke motor and I am learning to hate it!
Any ideas or help .
Thanks
 
Compression test will reveal little, as decompression engages when cranking.
I have never seen an MFS 4/5/6 with under a thousand hours that needed a valve lash adjustment.
What method did you use to check for spark?
Is the plug wet or dry? Wet=no spark; dry=no gas.
What plug are you running?
Why did you change carb and fuel pump? Did you test for fuel delivery?
What method did you use to disable kill switch? Did you test the switch with an ohm meter?
Did you test the ignitor with an ohm meter?
Is this a dual-tank motor? If so, are you running from an integral fuel tank, or external? If external, does the primer firm up properly? What position is the fuel cock set to?
 
What should plug wire to ground ohms be.This one is 3Kohm.
On mfs6c igniter has no exicter coil.
On the kill switch I just disconnected it.
 
This is external tank only and bulb is tight.
Also the few times it did start it runs great at all speeds.
Will never restart.
Thanks
 
Correct, the 4/5/6C has an integrated ignitor -- no pulser, and no exciter. Check your Factory service manual for DC resistance readings of the ignitor. 3K sounds way too low from memory. Are you using an analog or digital meter?
When it won't restart, what kind of spark do you get?
 
The plug is NGK DCPR6E.Had to go to boat and get plug looks normal to me
but I could be wrong .It has grey look not wet.Also gap .031.
 
The few times I had plug out to see spark it looked blue .
From my years of using 2 cycle motors it seemed OK.
Also no fuel shut off on this and I replaced fuel filter.
 
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