3.0 L Spring start issue

[Willy.Fire]

1999 Maxum SRL 1900
Had problems last year and got carbs redone which seemed to fix the problem in the fall. I put 1.5hours on without issues in fall after carbs fixed.
So when I pulled it out this year got everything ready it started great turned over 2nd time and idled around 900rpm for 12-15mins then sputtered and stalled out.
Now will start but wont stay running for more then 5 seconds.
Since this happened i filled tank with fresh gas 85L
(I know very little about carbs)Took top of carb off could not move the flap. Started it at about 1500rpm and got back to the flap and I could keep it running if i played with the flap moving it slightly but as soon as i let go it would stall out. Ran this way for a few minutes.
Anyways before I take it to someone for $150 hr is there some diy things I can try keep in mind I do not know much about carbs. I would like to learn but do not know anyone and can not find many videos about them. Thanks for any help.

 

[Sosebee88]

Gas now a days has ethanol in it. That ethanol developes a film on the needle that the float pushes. When that needle becomes stuck or sluggish it will not allow the carb to fill up with new incoming fuel. Just a thought. But small motors like mower and such are plagued by this now a days.

 

[ThomW]

Did you put any stabilizer in the gas at the end of last year? It sounds like something is up with the carb for sure...the float needle is sticking or a jet is clogged a little? Its strange that it started up and ran for a while, then died. Maybe it pulled up something cruddy with the gas and that caused an issue in the carb? You should be able to find a video on youtube or somewhere else that details how to clean a 3.0 carb. It's really not that hard to do, just take your time and when in doubt, take a picture so you can see how it goes back together! Make sure you buy a gasket set for the carb though, as then tend to tear upon removal.

Did you check the fuel filters? Is there a fuel/water separator?

 

[Bondo]

Had problems last year and got carbs redone which seemed to fix the problem in the fall. I put 1.5hours on without issues in fall after carbs fixed.

Ayuh,.... Welcome Aboard,..... The usual cause for the need to rebuild a carb is a polluted fuel supply,....

Last year, if the Entire fuel system wasn't cleaned at the same time the carb was rebuilt, the carb is now probably fulla crap again,...

is there some diy things I can try keep in mind I do not know much about carbs. I would like to learn but do not know anyone

Yes, yer darn tootin' there's plenty You can do,...

The 3.0l usually doesn't have a water separating fuel filter,...
Click on the links above, 'n go buy yerself 1 from iboats,...
The filter, 'n housing,... you'll need 2, 3/8" hose barbs, 'n hose clamps to tie it into the fuel line, just ahead of the fuel pump,...

Inside yer fuel pump is a fuel filter,... check, 'n replace it,...

Inside the carb at the inlet fittin' will be another filter,...

Pull a sample of gas from the tank, 'n leave it overnight in a clear container,...
Water will fall to the bottom, gas will be on top,...

If ya find crud in the tank, of course, it's gotta be cleaned out,... most of yer fresh gas will be salvageable,...

The hose barb at the tanks outlet is the anti-siphon valve, it can get crud plugged also,...

 

[Willy.Fire]

thanks for the replies. I spent a full day playing around with it. Changed fuel filters took the carb apart and cleaned it up to find out all it was was a bad idle mixture screw and throttle cable. I replaced the valve cover gasket last year and when i did it must have threw things our of wack somehow plus me being a amateur does not help. so I think i have the idle screws set right it took me awhile to figure out how to set them corredctlyt but followed mercury manual. thanks