[jerrymc]

I have 3-weedeaters (1-Echo GT200R and 2-Craftsman Weedwackers 31cc engines.All 3 have Zama carbs and I have put rebuild kits in all three but I still have excessive amount of fuel leaking from the carburetor throats when trying to start them. I have replaced the fuel lines, checked for binding or crimped lines--checked the gas caps--checked the muffler for excess carbon --adjusted the needle valves out about two turns. The Echo will run at idle with a full choke but will not accelerate to high speed. The two Craftsman will not even start.The two Craftsman trimmers have remote primer bulbs and I have double checked the routing of the lines which seems to be correct. I cannot figure out what is causing the fuel to run out of the carburetor throat.Any help would be appreciated.

 

[Rentahusband]

Seems like there is an issue with the needle not seating. Did you remember the little spring under the metering lever?

 

[jerrymc]

Weedeater Fuel problem

Thanks for the reply RAH--Yes, I actually reset the metering leveler even with the base of the carburetor. One thing I did that might be "dumb" is I blew 80 lbs of air pressure into the jets on all three carburetors. That's when I thought I may have ruptured the diaphrams on all of them--so I ordered repair kits for all three and replaced all the internal parts and I was careful to insure that the spring under the meter leveler was in properly. It just seems odd to me that all three would have the same problem because I have repaired a lot of 2 cycle engines and have never encountered this problem.I went to the Zama website and looked at the diagrams of their "typical" construction but I still don't see what could have gone wrong.

 

[Rentahusband]

Yeah, the 80psi was not a good idea. I did that ONCE on an Echo trimmer and damaged the internal check valves that are not serviceable. I never blow air directly into these carbs anymore. I spray the carb with cleaner and follow with air on the outside only.

 

[jerrymc]

Weedeater Fuel Problem

Absolutely correct !!! I won't do that again. I put an additional regulator on my air compressor and "toned" it down to 20 lbs. I checked the metering needle on one of my units and noticed it has a hard rubber point. I thought they were all solid metal--but not so. Also I will start using brake cleaner instead of carb cleaner on the sensitive parts. Thanks again for your help,I really do appreciate it !!

 

[Rentahusband]

All of the 2-cycle Zama/Walbro carbs I have seen, have the rubber tip needle. I have learned to turn my compressor down to 20psi when using on carbs.Did you have a solid tip needle on any of the carbs that were leaking?

 

[jerrymc]

Only on one of them. The other two are solid metal. I am going to try the "steel wool" theory today and see if that helps. The problem may be in the casting itself instead of the needle. Thanks again for your reply.

 

[30yearTech]

High pressure might damage a check valve, but that won't make a carburetor flood.

If you attach the fuel lines incorrectly with an external primer you can have a flooding issue. Make sure when you assembled the carburetor that the gasket goes first and then the metering diaphragm. Zama has different metering diaphragms that look the same and will mount on their carburetors but have different "buttons" on the metering diaphragm. If you don't get the correct one this can also cause a flooding issue.

Only on one of them. The other two are solid metal. I am going to try the "steel wool" theory today and see if that helps. The problem may be in the casting itself instead of the needle. Thanks again for your reply.

I have never run across or even seen a Zama diaphragm carburetor with a solid metal metering needle, what are the models of these carburetors?

 

[Rentahusband]

I am thinking all three needles should be rubber tipped.

 

[jerrymc]

Guess I need better glasses!!! After looking at the needles they are all rubber tipped--but they look like metal to the naked eye. The kits I am referring to are the RB-52--RB-107 and RB-142. I will check the fuel line routing again to be sure they are going to the right places. Thanks again for your help.

 

[Rentahusband]

I have to wear my reading glasses when working on these!! I learned that these use rubber tipped needles when working on a carb. I was putting in a kit and noticed the new needle was rubber tipped. I thought I got the wrong kit. The old one was tarnished silver so it appeared to be a solid needle. I wiped the tip off and discovered it was a rubber tipped needle.

 

[jerrymc]

Yeah, it's hell getting old. I tried again today to rectify the leaking problem but to no avail. Two of these weedeaters are nearly 10 years old so maybe it's time for them to "retire" also !!! I got the Echo to stop leaking but now it will only run on full choke---and only at idle speed. When I moved the choke lever to 1/2 it immediately dies. That's the one I put the RB-107 carb kit in. It's a GT200R. I really like it and the engine runs great but just won't accelerate.

 

[Rentahusband]

Yeah, I am not liking the getting older thing.
That is the same issue I had with an Echo trimmer, after I used the air hose on it. I am thinking you damaged the internal check valves on the Echo carb and will need to get a new carb. I replaced the carb and the trimmer ran perfect. I was not aware of these check valves at the time. So I no longer use the air hose directly into the carbs.