Vanguard 12.5HP/14HP/16HP/18HP carburetor cleaning

[MattA]

Have you put a new kit into the carb and have you checked the intake and carb base gaskets? Are you removeing the jets to clean them and the passage ways ?image.png
This picture shows the exploded diagram .

David I removed the main jet and attempted to clean the main jet and every passage way I could find several times. Intake manifold to cylinder gaskets were replaced + I carefully cleaned both mating surfaces. The carb base and carb gaskets were not replaced at this time but were replaced in 2019 time frame the last time I pulled the carb for cleaning. The carb gasket is probably a 10 minute job... could easily try that. Carb base requires disconnecting the engine and pulling it apart. I have not put a new carb kit in. Sometimes the coils go on the Vanguards. I have not put any research into this recently.

I forgot to mention yesterday that several times when I shut the engine off it backfired. It normally does not do this. The last time I shut it down, I let it idle for 30 seconds or so and the engine did not backfire.

The main jet is not the only source of fuel at full throttle . The emulation tube and the thickening tube are part of the idle and mid range circuits . If these are restricted it will lean out as well . On many carbs air fuel siphon passages pass through the gasket between the top and bottom . If the gasket is no longer sealing in these areas it can also cause lean out . If your float is too low , this also will cause lean . Baddly worn throttle shaft holes will lean .

I ordered a new carb gasket, carb to intake and carb to air cleaner gasket (I know this isn't part of the problem but I might as well replace it while its apart). I might try to check for gasket leaks with a can of carb cleaner. I haven't tried this but there are plenty of how-to videos.

[MattA]

Briggs can be very finicky and a pain. They to start they are extremely under fueled and run borderline lean when in good shape and from new.... It takes very little to make them unhappy as far as dirt and or bad fuel/water etc. We have most parts in stock including new OEM carbs, pumps, gaskets etc, you are close by you could also bring it by would be glad to check it out. Posting a video may or may not help.

Thanks Ryan. I may take you up on your offer if I can't get it resolved. We have an ultrasonic cleaner at work I could try cleaning the carb in.

[CaseIngersollNE]

Any time let us know. Feel free to call anytime too and bounce things off us maybe talking something else may trigger in my mind lol Ryan

[MattA]

I replaced the carb gasket this week and also shot some carb cleaner through the various holes in the carb while I had it apart. The pilot jet was nice and clean. Still lacks power. I tried adjusting the carb a bit. I left it a tad richer. Towards the end of the carb adjstment procedure, there is a step to hold the throttle linkage against the stop and adjust for 1200RPM. Previously I had used 1600RPM from a post on the old forum by Bob MacGregor. Changing the stop back to the recommended 1200RPM brought back some minor surging at idle. 1600RPM basically masks the problem. I also made some minor governor adjustments to make the engine idle in the 1750RPM range as per the service manual. Still lacks power. Spark looks ok with my spark testers. I pulled the carb cover off last night, opened the anti-fire solenoid and shot enough carb gleaner through the main jet that I filled the carb over the jet. I let it sit for a bout 15 minutes before cleaning out the carb. Seemed to run ok at mid throttle today putting on fertilizer but with some minor surging at idle. Sounds like I'm taking the carb off again We do have a new ultrasonic cleaner at work I may be able to soak the carb in.

[DavidBarkey]

Matt , did you ever check your float height ? If too low it will also cause to run lean .
Have you checked compression ?
Have you tried a different set of spark plugs ? I know they are long life but that doesn't mean they can't go bad .
Spark plug colour . What does it say ?
Maybe more than one thing is going on .

Away to prove or disprove lean condition to add a small amount of propane while under a load add some extra fuel and see if it improves . To do this , take a standard soldering bottle . Remove the flame tip from the valve and attach a piece of hose over the tube long enough to go into the breather while you are sitting on the seat . Get out and load it up , then crack open the propane bottle a little . If it is lean , it will come to life . If is something else it will run to rich like on choke .