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

[MattA]

Well I got about an hour of free time tonight. Pilot jet was again plugged. I stuck a piece of stripped 26AWG? solid core wire though the pilot jet several times and nothing came out. Didn't seem to clear the end hole out either. Compressed air shot backwards through the jet cleared the end hole out. I also shot some crc carb cleaner through the pilot jet a few times letting the jet sit between cleaning attempts. I also shot compressed air down the pilot jet hole. The last thing I did was drain the fuel tank through the existing filter and install a new filter. The old filter had plenty of flow. Maybe a quart or so per minute. It's raining and the kids are asleep. I'll run it in a few days when I mow the lawn.

Well, I'm confused though, by the source of material which plugs the jet . What do you think?

I was thinking the same thing. It’s a plus for sure that your able to see the problem and clean the main jet but there seems to be an inordinate amount of junk getting into the carburetor. I was thinking it might be worth pumping some gas into a clean container to see what’s in it. I realize this has a plastic gas tank but there still could be junk in it.
The filter had good flow but it’s possible it’s letting junk through as well.

Just some things that came to mind as I was reading. I’m interested to see what you find.

I've got a new OEM briggs filter on it now. I'm thinking it may be possible that I'm simply not getting the junk out of the pilot jet. The carb still looks good and clean inside. I'll keep you guys posted.

[MattA]

I chopped up to about 8" of thick heavy grass off my lawn tonight. It's been raining a lot here in recent weeks. Anyways the engine ran much better. Seems to have a bit more power now which I really put to use tonight. The engine still seems to hunt a bit at any rpm but it's much better than before. I'm going to perform the carburetor idle fuel adjustment, correct the governed idle rpm (1200rpm to 1750rpm) and set the governor stops per the service manual. Hoping to do this tomorrow and then mow my lawn again to remove the thick layer of grass clippings.

[CaseIngersollNE]

The Briggs can be very finicky. As far as the governor adjustment you may end up regretting at they too are very temperamental with this as well and you can create more aggravation for yourself. There is a special tool for adjusting the tabs and if tackling this I highly recommend getting it. Now again with the temperamental Briggs, you really need to pull the the carb off to clean right, pull all the jets, the bottom one you can only get by pulling fuel solenoid. and really should pull welsh plug, clean passages and put new plug in. Be careful with compressed air as you can blow welch plug out so dont use lots of psi. If you have access to ultra sonic cleaners they are great. We do a lot of carbs,many also sent to use for rebuilds or cleans. We use a heavy chem dip and soak, and 2 cycles through a good quality ultra sonic at temps of 175 degrees, then do the manual and air cleaning before assembly. Some times you can get away with pulling the top of the carb and spraying what passages and removing what you can. But if it keeps happening you should pull the carb. The Briggs are very fast and easy to pull the engine. We have a video on how to pull the Brigs for Head Gaskets, coils, carbs etc. Good luck.

[MattA]

Well you guys already know what happened
Before mowing this past weekend, I set the governed idle to about 1500rpms. I also did some reading on the old forum and Bob macgregor aka mad Mackie had recommended increasing the carburetor idle stop from 1200rpm to 1400rpm or 1450rpm. I did about 1400rpm. When I started mowing, the rpms climbed to about 3800rpms. I adjusted the governor high rpm tang to bring the rpms back to 3600 or so. I haven't made adjustments to the high rpm tang since 2019 when I increased the rpms from 3300 to 3600. Anyways power seems to be down a little. The tractor struggles to climb the small hill in my front yard more than usual. When I finished mowing, the surging was back. I'll pull the engine, clean under the tins and clean the carb at the end of the mowing season. I haven't done that since 2019.

[MattA]

So back to this stupid problem. Last fall I pulled the engine apart, cleaned the debris from the engines cooling fins, took the carb apart and tried to do a good cleaning. I actually attempted cleaning it several times to make sure it was good and clean. I put it all back together and the tractor started much easier and seemed to run better. Mowing season was over at that point but I did get two lousy snow storms over the winter to use it. Ran ok but seemed down on power. Over the winter at @DavidBarkey suggestion, I checked the valve lash and the plug gap. Valve lash was 0.005" and the range is 0.004" to 0.006". Spark plug gaps were 0.0295" and 0.030". Recommend gap is 0.030". Plugs are Briggs and Stratton 694385 long life plugs. Plugs have about 250hrs on them and are about 6 years old. I believe the air and fuel filters were new last year and I just changed the oil + oil filter.
Today I attempted to cut my grass and the tractors so down on power that its basically useless. Runs 3600-3700RPM with no problem but driving up the small hill in my front yard with the deck running causes the rpms to drop rapidly. Same for thicker grass. I can literally be doing like 0.5mph or less up the hill and rpms are below 3000. I pulled one plug wire, started right up and idled. Swapped pulled plug wires and again it started right up and idled. I even tried engaging the deck with either plug wire pulled. The engine struggled in both cases. Gas cap vent is clear.
Most of the gas in my tractor was from last fall. I only used about a gallon over the winter blowing snow. I put stabilizer in it last fall. About half a gallon of the gas was 109 octane ethanol free race gas (how I got this is a bit of a $70 sore spot). I added about a gallon of fresh gas before mowing today. This gas was purchased within the past month. An our into mowing, I added another gallon of fresh gas and when finishing I added another gallon of fresh gas. Hard to tell but I think I burned around the usual 2 gallons of gas while mowing. I don't think the gas is the problem, most of the gas in the tank is new.
I'm really frustrated with the tractor running like crap. I'm open to suggestions. I do have a pair of Briggs and Stratton spark testers: https://www.amazon.com/Replacement-Spar ... B01I8ALYPS I tried these today in the driveway but couldn't see crap. I think I need to try in the garage. I haven't done a compression test. I could rent a compression tester and do this.

[DavidBarkey]

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 ?

This picture shows the exploded diagram .

[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.

[DavidBarkey]

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 .

[propane1]

Frustrating problem Matt. Hope you get it fixed.

Noel

[CaseIngersollNE]

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.