Fun McCulloch 3200 saw primer bulb not working but runs!?

Arborist Forum

Help Support Arborist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

B.C.

ArboristSite Operative
Joined
Jun 9, 2017
Messages
178
Reaction score
36
Location
Flint MI
Worked on a little Mac 3200 today. Needed new lines and the primer bulb seemed pretty shot too. Put all new in, and was surprised when the new bulb wouldn't pull any fuel? Made bubbles, and I think I can hear it sucking air from the carburetor, but won't pull any fuel. Thought I had it messed up so I reversed the lines, same thing. Its really weird. Figure it must be a check valve in the carburetor. Tried another older primer bulb too, also same. Didn't think it would run but I gave her a few pulls and off it went! Ran pretty good too for not being run in who knows how long. Had to crank the idle up 2 full turns to keep it going good. Carb looked fine inside btw, pretty nice & clean, and both diaphragms were in good condition. I was surprised that it ran, but then I don't know a great deal about how exactly the primers work. It's a zama carb. Just thought I'd share my experience because it was really unexpected.
 
That's whats funny about it, it still runs fine, and the primer line never fills, doesn't work. Just sucks air if you push it and bubbles in the tank. But it runs. Made me kinda really curious how, and if maybe the primers aren't as important as I thought. I have no idea, thought it was kinda neat if not odd though.
 
If the primer is hooked up correctly so that it sucks fuel from the carb and dumps it back into the tank, the two check valves in the primer will be pointing the right way and if they are functional, the primer will have no effect on how the engine runs. The fact that it doesn't seem to pump fuel usually means there is a check valve in the carb that is leaking and the primer just pulls air back through it rather than suck fuel up into the carb. If the engine starts quickly with just the choke, you don't need the primer, just plug the line between the carb and the primer with a small ball bearing and forget it. If there is a faulty nozzle or body check valve, it could be a source of erratic operation of the engine.
 
Only reason for a primer is for easier starting when you run out of fuel. Got a few Poulan top handle saws you wished had a primer, takes for ever to primer 2 miles of fuel lines. Steve
I've taken to charging the carb throat with mix...I ain't got 30 pulls in me anymore.
 
Back
Top