What causes engine stutter?

[BillyDBrown]

I have a relatively new and maintained BCS 749 with Honda GX390 engine. We've mainly been very happy together but . . . .

The engine makes a VROOM?VROOM?VROOM kind of sound rather than a constant hum. When doing this, it also feels like it loses some power. I notice this when pulling my wagon uphill even when empty. The wagon has good wheels and bearings and causes little drag. This sound pattern may occur when used otherwise at other times as well but I can稚 be definitive since I haven稚 used it for a while. I think I ran into this blowing deeper snow last year too. Most likely whenever it has to work a little harder.

My fuel has always been clean.

Any thoughts what might be causing this problem?

 

[RalphVa]

I'd try putting some SeaFoam in the fuel tank. Sounds as though there could be some very small restriction in the high speed jet. I've used SeaFoam in carbed engines and have avoided a number of carburetor teardowns. It works.

Ralph

 

[BillyDBrown]

I've actually been using 100LL air gas as per EarthTools advice, so there shouldn't be any varnish. Recently, however, I also started using Sea Foam. Perhaps, if I'm lucky, it just needs some time to do its cleaning.

Alternatively, I could also drain the carburetor bowl. Haven't don't it yet but it seems quite simple. It's just having run the air gas, it wouldn't seem that the carburetor would be the issue. It seems like that's what came to your mind though. Are you pretty sure that's it?

I suppose its possible that a little dirt could have fallen into the gas tank when filling it. That would produce the same result wouldn't it?

 

[ruffdog]

It does sound like the main jet circuit is a bit lean to sustain a load on the engine. Debris could cause it as well as a low fuel height (float level) will affect it.

 

[WesKootenay]

I agree with the replies above, the engine is starving for fuel (or possibly air?) when under load, known as 'hunting'. When the engine is put under load the governor rod opens the throttle but the engine can't rev up so the governor backs off then tries to open up again etc, etc. Partially plugged high-speed jet or in-tank filter, float level too high.
Should be a simple fix.

Good luck :drink:

 

[BillyDBrown]

Thanks Guys!

Sounds like its likely the carb. I'll give Sea Foam a bit more time. If that doesn't work, drain the carb bowl, and, if that doesn't work dig in some more.

 

[dragoneggs]

Only other thing might a be a dirty fuel filter if it has one. That can starve the carb.

 

[WesKootenay]

Only other thing might a be a dirty fuel filter if it has one. That can starve the carb.

Yes, it has an 'in tank' one, part of the petcock. That was the problem with a neighbor's GX powered generator.