Steve, just a couple random thoughts on intake puffs. Please don’t take them for thruths. They are only feelings and guesses from my part, based on a mix of my own experiences and what others shared.
Different engines behave differently. As far as I know I never had an intake puff on my first two rigs. The third one is another story. Apart from that it seems a few things can worsen the situation.
Leaks, condensation, soot, tary fumes or a combination of two or more of them.
Tary fumes are less likely since your rig is a charcoal machine - unless you happened to feed it brands.
I don’t think dry soot will cause puffs, unless some larger flakes let go and interfere with an intake valve. Soot in combination with condensation makes it stick and can let go when dried out.
Early burning leaks could create condensation downstream in the system (and delutes the gas with CO2), even if the gas is dry to begin with.
Leaks in general delute the gas, but that’s obvious.
I have no experience with charcoal gasifiers, so I won’t go into anything like worn nozzles creating not focused enough heat, ash content in the charcoal, fuel size or anything like that. Just rambling…
Thank you Bob, Don, Goran, Kristijan, Tom, Wayne, and JO. Sounds like it may be the result of a leak. Kristijan and Tom, were a bit more creative in their diagnosis of “leaks.” Ha! Ha! I have already done leak tests on the gasifier. The only thing I didn’t check thoroughly was the gas line from the back to the engine. I was wondering if it could be engine valve problems. I hope not. Other things I can fix. One think I didn’t mention was that when cold weather arrived this fall, I put a piece on the carburetor to hold the choke open. The rash of intake pops occurred after that, but the difficulty starting has been going on for at least six months. I’ll test the gas line and put the choke back like it was and let you know the results. Thanks for your input.
JO described it well. In my experiances, weak gas or lean mix are most likely culprits for puffs. Both the resault of leaks, but dependant on leak position (as JO sayd).
I think SteveU once descriced what causes the popps, fuel burning so slow it still burns at the next stroke or something like that.
I dubt its a valve problem thugh. I had the same problem on my BCS walkbehind, it kept popping and throwing the filter lid off and l culdnt find the problem for weeks. Torn down the engine, polished the valves, no better. Then l found it, a crack in the hot part of the gasifier. A LEAK.
A good practice thugh l learnt from Tone is to pour some oil down the intake just before you kill the engine, if you plan to not run it for a while. Snowmobile guys did it all the time here but l never thod about using that in our feald also.
Update: Today I checked the 18 foot sump pump hose for leaks and found three small holes which I sealed up with electrical tape. Then I tested the 5 foot long, 2 inch galvanized flex exhaust pipe. Turns out that it was held together by rust. That is obviously the source of the toublesome leaks. I have enough flex exhaust to replace it a couple of times, then I’ll need to find something more permanent. The experts unanimous diagnosis was correct. Thanks again for your input. I expect to be “on the road again” next week.
The way the gas line, blower, and filter are arranged, I only need one valve, the air mixture valve which is located on the left side of the T fitting on top of the carburetor.
I will try to upload the latest brochure here. The photos shown above have been included along with some text update, and an updated drawing of the gasifier.
