OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Chainsaws and Concrete Cutters McCulloch Chainsaws Carb issues MAC 3818

Hi guys

I have a MAC 3818 model 11-600038-29 that I bought second hand. The carb was full of gunk so I put a kit through it and cleaned it with carb cleaner. I noticed the previous owner had the H needle in the L needle position - longest screw should be L so corrected it.

The carb I have is a Zama C1Q-M33C. I've downloaded the Zama Parts and assembly diagram so everything is together correctly ie: gaskets in right order. I've even popped out the welch plug and installed a new one.

Also replace primer bulb, fuel lines and fuel filter - horrible job on this saw.

Issue.....starts on half choke but dies flicking it to run and won't idle. I've tried setting up idle to 2 full turns (4 half turns) and same for H as a base line. Start on full throttle and adjust L to try and get idle. The closest I got was Idle on half choke. I've checked the height of the metering system with a straight edge to a whisker of a gap under the straight edge..(Z gauge now ordered) but I cant get it to idle. I did notice fuel spitting out of intake past the Venturi valve./Butterfly valve top of intake port.

Now I'm thinking just buy another carb. The C1Q-M33C is discontinued. I think I can also use WT-774 (online its very expensive 70-90 bucks - Im in Australia and shipping is a killer). From research I think I could possibly use WT-674, C1q-m36, WT-439 but all are not able to find. Can I get a C1Q -XXX carb and use the body of the carb and transfer the essentials across from the C1Q-M33C? Venturi is 12.5mm.

Can anyone make a suggestion for alternative carb?

Regards

Aussie280

Pull the muffler and check the spark for carbon clogging.

BTW I never use carburetor cleaner on these carburetors, too delicate parts that it can be damage just like compress air can damage them. All my carburetor cleanings go through ultrasonic cleaner using soap and water.

Cleanup my wording on this one. Boy my back must had been more than I thought.

Yes good suggestion...did that, the screen was clear.

I'm basically just after another carb if anyone can help? Even a s/hand might work.

Hi Guys, a bit of an update I managed to source a WT-774 carb in UK via good old eBay. I'd still like to replace the Valve check 0008004, and retainer, check valve 0009008 on the Zama carb. Has anyone removed the Welch plug before on these carbs..having trouble finding these parts too. How do you deal the Welch plug? It's oblong shaped.

Well looks I am running late on this one.

Don't the retainer as it is NLA. As for welch they just a thin piece of aluminum and a sharpen pin punch will remove it. Just be careful not the damage the under laying surface.I actually got a set install punches for installation those bango welch plugs along with the triangle shape ones.