Carb issues???

[jtstric3]

I have lycoming 0-360 with carb and mags. I have stumble on hard acceleration with puff of black smoke and back fire/pop after letting off from wide open throttle run. I’m assuming too much fuel. Accelerator plunger was replaced couple years ago and still seems to be in good working condition. I would normally take to greg Mcloud but RIP. Have been running fine for years on this set up and I haven’t changed any lean/rich settings which my carb has one. Any feed back or direction would help. I have taken carb apart and clean but did not remove economizer valve as not very familiar with how it works.

 

[Slidin Gator]

Check your intake tubes etc. for a vacuum leak. Backfire when letting off is the tell. Probably time for new gaskets and possibly replace the hose couplings.

 

[jtstric3]

Thank you I’ll check tonight when I get home

 

[jtstric3]

Can’t find any intake leaks with starting fluid. Definitely getting too much fuel. This is after letting off. Stumble seams to be after accelerator pump and as economizer valve/main jet kicks in. Is factor lean Rick setting 1.5 turns out?

 

[jtstric3]

I can’t figure out how to post video

 

[jtstric3]

https://southernairboat.com/community/media/img_6228-mov.98352/

 

[John Fenner]

First off, set idle stop up to about 600 RPM, "safely" run the idle mixture screw in till it falters, back it out till it runs crisp, may have to back idle stop down to 500 RPM.
If it still has a stumble, the pilot jet or circuit could be an issue.
At wide open throttle, does the peak rpm increase a bit with leaning the lever a bit?

 

[jtstric3]

First off, set idle stop up to about 600 RPM, "safely" run the idle mixture screw in till it falters, back it out till it runs crisp, may have to back idle stop down to 500 RPM.
If it still has a stumble, the pilot jet or circuit could be an issue.
At wide open throttle, does the peak rpm increase a bit with leaning the lever a bit?

Thank you I will try that and let you know

 

[jtstric3]

Check your intake tubes etc. for a vacuum leak. Backfire when letting off is the tell. Probably time for new gaskets and possibly replace the hose couplings.

So I tried adjusting idle-lean/rich and it did not help. I can’t find any intake leaks. It’s definitely getting too much fuel. I noticed now I am unable to shut boat off with lean rich now.