ProMac610 chainsaw repair

chas045(7b)July 11, 2012

I have a McCulloch PM610 chainsaw. I bought it new and use it occasionally but it has probably sat for four years. I think that I may have run it to dryness. I bought it new. Perhaps it is 12-15 years old. It was often not easy to start but it ran well once it fired up.

In any case, it isn't starting now. It has always been harder to pull than my smaller saws. I assumed that was compression but not sure. I was just noticing that the cord was not retracting easily and I am wondering if the extra effort to pull the rope makes it too slow to easily start? I was able to get a couple of half second runs if I dribbled a little gas into the carb.

I just ordered a carb rebuild kit. I have not worked on these little box carburators before (I guess I have been lucky). Most of my experience is on lawn mower (or bigger) size engines with float bowls etc.

I took the carb out and took it apart. The seals and valve flex thingies seem flexable to me and they don't have holes or tears. However a web site of a similar walbrow carb said that even somewhat stiff is no good. That is why I ordered the kit. The fuel line doesn't seem to be clogged. I blew on it and I could hear foaming bubbles coming out in the tank.

The whole carburator looks like it is brand new to me. Quite a change from my usual carbs loaded up with some crud in the float bowl. Anyway, do you think I am on the right track here by replacing the flex valves and fuel pump spring/rubber thing, or is there some other obvious thing that I may be missing.

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Sounds like you are on a good track IMO.

1. Double check the fuel lines, in tank filter and primer bulb (if equipped) good for deterioration and restriction (pull the filter if in doubt if no signs of trash is in the tank).

2. My challenge with the little carb is replacing the small recessed fuel filter, which clean easy with pressurized carb cleaner below and above it. There is usually fine trash in it restricting fuel flow but I try not to rem it.

3. Rem all adjustment screws and pressure clean their ports and all ports. Count screws turn down to reset them close for restarting and tune if needed.

4. This is usually my extent of cleaning if the eng runs or tries to run vs hrs of soaking if the carb has hard varnish.

5. Lack of use is not good on engines. I treat all my fuel with StaBil and start "All" engines yearly with fresh fuel 5-10 minutes regardless or alternate use. I leave the fresh treated fuel off-season w/o a problem.

6. There are youtubs on cleaning/rebuilding the small carb.

7. Check your manual to see if it has a compression release button to make the starting easier.

    Bookmark   July 12, 2012 at 5:16PM
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Thanks loger. I was hoping to hear from you. I will check the manual but I don't recall a compression release and it doesn't have a primer bulb like my smaller saw. [Those primer bulbs go bad fast these days]. The youtube info I looked at showed how to remove the screen (sort of) and how to reseat it but like I said it appears to be very clean and I don't see any crud anywhere, but I will check it anyway.

Unfortunately, I think at that time I hadn't gotten into the habit of using stabil which I now always use, but i think there is a 50% chance I didn't leave it with fuel.

Fortunately I do have air, and will remove and reset the low, hi and idle ports and blast anything else I can get to.

    Bookmark   July 12, 2012 at 7:34PM
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