Zama C1U carb pump flapper valves and ethanol......

[ol'homey]

Last Oct I ran all the gas out of my little Echo trimmer and put it away. Tried to start it today and it would barely idle, bog on acceleration, and run lean and cut off at WOT. The H mix screw had no effect. Pulled needle out shot carb cleaner in, no joy. Pulled the metering diaphragm off and shot carb cleaner through both the H and L circuits, both were clear. The metering diaphragm looked fine, soft and pliable. I put a GND-12 (fits the Zama C1U carbs) kit in it 2 yrs ago so I expected it to be fine. Pressure tested the needle valve, checked out fine. Checked metering lever height, was level with the carb body gasket surface which was fine. Put it all back together, no joy. Took carb off again. This time I took off the fuel pump diaphragm cover. First thing I noticed was both of the little flapper valves were all curled up and not even covering the holes. I've never seen them all curled up like that before. I remembered that the kit that I got had 2 fuel pump diaphragms in it. One was made of the same material as the metering diaphragm which is the one I used (and today found curled up). The other was made of some kind of thin plastic (mylar?). Luckily I found the plastic pump diaphragm still sitting in the bag the kit came in a box under my work bench. Installed the new diaphragm and the little Echo trimmer runs like a champ again! Questions:
1. What caused the flappers to curl up like that? Was it the 10% ethanol?
2. Did Zama update the material used in the fuel pump diaphragm to plastic to better resist ethanol?
3. Is this problem (curled flappers) unique to the C1U Zama carbs or have you seen it in other (ie. chainsaw) carbs? How common is this problem? Thanks, Lee

 

[PWB]

I'd be tempted to blame it on the carb cleaner........ Some of them have chemicals that will eat just about anything, 10% ethanol shouldn't be that big a deal.

 

[fourfivefour]

Maybe you blew it out with the carb cleaner.
Good job saving the old kit.
I always save what's left of kits and the old diaphragms go back in the bag. They may come in handy some day.

You have to be careful, some carbs have little diaphragms, screens, check valves that are easily overlooked and you can blow them out with carb cleaner or air.
Don't ask how I know.
I now look up a carbs exploded view before I take it apart so I don't blow anything away and loose something small.

 

[ol'homey]

Maybe the flappers curled up from sitting dry for 5 months? I always drain the fuel and run the carb dry before I put it up, same as I do for my saws and other equipment. Never seen this happen before though, and wouldn't expect it on a 2 yr old kit. Hopefully the new plastic diaphragm that came in the kit is the fix for this. If not I guess I'll be putting a new one in every yr or 2. I think the Zama C1U carbs are used on quite a few small cc engines including chainsaws. How about it Lake, ever seen this before?