Home › Forum › Ask A Member › Martin 40 ~ 45 running issues › Reply To: Martin 40 ~ 45 running issues
Buc, Sounds like everybody was having problems the last couple of days trying to log-in, seems like it is working now. What gaskets did you replace if any, head gasket?, possibly leaking between cylinders, although 5psi difference is nothing. 9olbs should be plenty to fire that motor up. Next question, are you sure you are not loosing spark on either spark plug when motor decides to shut off, you need the boss out there to watch those spark testers when the motor is shutting down on it’s own, at least you’ll be able to check off ignition on the list. Carbs are another deal all there own. I had a couple different 4&6hp Johnsons, 70’s models, which the carbs were not very friendly, was the air-fuel mixture screw tip was worn off, from someone screwing mixture screw in to tight. Another problem was not using correct packing gaskets that hold needles snug, were leaking, couldn’t adjust carb. Does that motor have reed valves in it, if so one of those may not be sealing. I’m sure you have seen the old Tecumseh carbs, along with Walbro, chain saw carbs, it only takes one of those metering holes to be plugged up, and you have a carb that will drive you nuts, even with new carb kits. That’s where the Ultrasonic tool comes in handy.
Needle packing tight on HS needle, none used on low speed air adjustment.
New gasket set, including crank seals.
No water droplets found on plugs or observed in cylinders.
I shorted out one plug wire at at time, and motor stalled each time, so
yes, it seems to be firing fine, and plugs were a tan color.
This one is a poppet valve carb, with new o-rings.
I’m getting sick of looking at it, lol
Prepare to be boarded!