More help with ProMac 610 Chainsaw?
I recently posted about my 15? yr old ProMac 610 McCulloch chainsaw that wasn't starting (not that it was ever all that easy to start). I replaced the pump and valve flex parts. I blew out all holes I could get to. Unfortunately I did forget to remove the screen but this carb did look completely brand new with absolutely no evidence of crud of any kind anywhere. I cleaned out the air filter that was quite crudded up. I also loosened the mounting nut that held the starter rope and that gave more play so that the rope pulled more easily.
Unfortunately I have not yet solved my starting problem although I may have made a couple of improvements. I have now been able to actually get the saw to run for a few moments but not enough to make any adjustments to keep things going. I am hoping that someone could give some ideas for improvement.
This saw does not have a primer bulb. I have read the Walbro general small carburator theory site and vaguely understand what is going on. Most importantly I know that the choke is imployed initially not just for cold but to bring fuel to the carb. On my smaller saws, with primer bulbs, I have always successfully pushed the chokes to half off after the first indication of firing and gotten the saws to start and run immediately. I am not sure that this is what I should expect with this more powerfull non primer bulb saw.
I have used erratic starting sequences that have occasionally given me a half to two or 3 second run. My high and low air adjustment screws are set to one turn out as directed in my manual. There is an idle screw that I don't understand. It appears that it presses on some pin on the carb, but I don't understand what it does or where it should be set. In any case, for starting I have the fast idle device activated.
I was having little or no success until I recalled that vacuum in the gas tank might depress fuel flow and I loosened or removed the cap. I also remembered that one old saw I had for years, often needed a clean or new spark plug to fire it up and I replaced the old plug too, although the old one looked clean, if a little wet (which would make one wonder about whether fuel starvation was an actual issue).
Anyway with those changes (whether effective or not), I was able to get the saw to rev up strongly several times. I believe I was able to get my hand smoothly around the throttle trigger where I would expect to be able to control the idle, but it always died on me after two seconds or less. Then it would take several (or many) pulls and manipulations of choke setting or whatever until it would fire again.
One last issue. The rope nut adjustment is a little odd. After loosening it a little, it pulled smoothly and then after many unsuccessful start attempts, the rope begain to tighten up again. I assumed that I was going to have to remove the housing and lock the nut down somehow because it was probably just tightening back up. But in a few hours, and again next day, I would find that the rope pulled easily again for 10 or 20 pulls before again tightening up.
Does any of this seem familiar to any of you guys?