Hello,
I have ~2005 Husqvarna riding mower with a Briggs & Stratton Vanguard engine (model #385777), that has started running poorly. The first time this happened I was pretty sure that I had gotten some bad gas... it started missing a little, then progressed to backfiring, and finally noticed that the muffler was glowing orange. Simply draining the fuel tank and refilling with known good gas seemed to fix the issue.

After a couple weeks, this issue happened again. This time, I crimped off the fuel line and let it run out of fuel, then replaced the filter, and it again seemed to run fine; however, after letting the mower sit for a few days, it happened again. It has now gotten to a point where it does it all the time... do see some dark smoke out of the exhaust as well.

I've blown out the fuel lines, replaced the gas again, and have now removed the carb to check the needle/seat... I did notice a very small bit of trash in the bottom of the bowl, but not much at all... other than that everything looks normal to me. I was planning to blast it out with some carb cleaner, and then blow it out good with air, but after that I'm not sure what else to try (if this doesn't fix it).

Also wondering how low the float should be set?

Any other suggestions would be greatly appreciated!

My Husqvarna with the Vanguard engine 385777 had a similar problem. After 2 ½ years, and 50 hours on the hour meter, it started emitting black smoke from the exhaust. I could see that it was running too rich. My assumption was the air filter, and I replaced it, but the black smoke was still present.

I searched the web to see if anyone else had the same problem, and I found a little bit of information. I do know the problem has to do with carburation; the engine is simply getting too much fuel. The two capped mixture screws on the top of the carburetor are for idle adjustment, but there are no adjustment for hi-speed.

I disassembled several pieces until I could look into the carb while the engine was running, and I observed that the throttle plates barely opened at full speed. Since the plates did not open very far, I felt the idle mixture screws could still be pulling fuel, and they might need adjusting. I pried the plastic limiter caps off the adjustment screws, lowered the engine speed down to idle, and adjusted the screws until the idle was smooth. Wow, what a difference it made at idle. The idle speed is now very smooth, with no popping or surging.

However, the original problem was high-speed flooding. I cranked the throttle to full, and the engine did not emit the usual black smoke. I put everything back together, and mowed the yard. The engine ran superbly; I had forgotten what it was like, and I sure liked the improvement.

It may sound strange that adjusting the idle screws fixed the problem, but it worked for me. Remember, you will need to pry off the plastic limiter caps to make the mixture correct. After the adjustment, I put the caps back on. The cost of repair is zero dollars, but it will take about 20 minutes of time.

Tennessee or anyone,

I have a Vanguard engine 385777 with similar problems as rreemo and Tennesee, is there a successuful fix to the issue. Tennesee did your fix last. Eveytime I try something, weeks later it comes back. I'm considering buying a new engine.

Yes ALPHA7, the fix did last. Still working today just fine. All I did was pry off the limit caps from the idle mixture screws and adjust the screws.

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Originally Posted by Tennessee

Yes ALPHA7, the fix did last. Still working today just fine. All I did was pry off the limit caps from the idle mixture screws and adjust the screws.

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Can anyone show some pictures as to where this limit caps are, I want to make sure I am doing it correctly