Briggs & Stratton 5.5 with plastic carb stalling issues

[kbowley]

Are you using gas from the same can after cleaning the carb? You are either getting water in the carb or your fuel cap vent is plugged up. First, get rid of the gas in that can completely, then soak the fuel cap in some warm soapy water for 15 minutes then slosh it around for a minute or so, rinse it out and try it, I most definitely do not recommend drilling the jet out. The engine will run perfectly fine if all is clean and correct. Also, when cleaning the carb, blow some carb cleaner through the fuel inlet with the needle valve and float attached but dropped downward. Also, you really need one of these kits to truly clean the jet.

 

[Chris142]

Put a more efficient fuel.fikter on it?

 

[Sophie]

Are you using gas from the same can after cleaning the carb? You are either getting water in the carb or your fuel cap vent is plugged up. First, get rid of the gas in that can completely, then soak the fuel cap in some warm soapy water for 15 minutes then slosh it around for a minute or so, rinse it out and try it, I most definitely do not recommend drilling the jet out. The engine will run perfectly fine if all is clean and correct. Also, when cleaning the carb, blow some carb cleaner through the fuel inlet with the needle valve and float attached but dropped downward. Also, you really need one of these kits to truly clean the jet.

Hi kbowley, thanks for your advice. Yes, I did the things you recommend during my first repair attempt. When I dumped the gas tank, I let it sit in a clean glass container for a while so I could check for water and sediment. I refilled the tank with fresh gas. Of course I tried running the engine with the gas cap removed to rule out any issues with the cap. None of these things made any difference. The engine still sputtered to life, ran for a few seconds, then died. Over and over and over.

I really didn't want to drill the jet; it sure seemed like a bad idea. I only considered it after doing more reading about problems with these plastic carbs. I sure wouldn't want to do it on any other engine unless all the evidence pointed to the jet (as it did in my case).

Small engine repair is usually so simple and easy that it's not worth my time describing it on a web site. I only posted here because the ultimate fix was unusual.

After I reassembled the engine, my husband took the mower out and spent an hour mowing our giant lawn. He reports that it starts and runs like new, so we're both happy with the outcome.

 

[danomichaels]

Adding to this thread... because I haven't read (unless I missed it) where anyone considered the possibility of trash entering the carb from somewhere other than the fuel tank.

I've cleaned this dern thing so many times now... I'm over it! So now going down the road of finding a fix. One common experience is that I find tiny pieces of grass in the carb bowl. Finally decided to empty and clean the tank, just to eliminate the possibility that its my fault by allowing grass to get in there while fueling. That said, I doubt the grass clippings I find in the bowl are getting through the screen in the bottom of the tank.

This past time, I drilled out the main jet... but I might have gone too big. Wouldn't run worth a... afterwards. Fortunately, I had a new carb on standby for just in case. I robbed the jet cartridge out of it, stuck it in the existing carb and just ran it as is. Just wanted to "control" the test - see what really makes a difference. Runs perfect if/when everything is clean. So... I struggle with the idea that opening the main jet is honestly necessary. Not saying it can't help... would certainly allow more tolerance on the sediment or other trash in the bowl. But just doesn't seem necessary because the engine runs perfectly after cleaning.

So, I'll turn back to the WHY is trash getting into the bowl. Again, its usually the smallest of grass clippings. I feel like clippings are being drawn in from the intake side of the carb.

After I don't know how many times I've removed the carb for cleaning, decided to look at a parts schematic. I realized that I was also missing the o-ring that goes between the carb and engine. Thought I was onto something... I wasn't. Got the o-ring installed, when ahead and cleaned the carb since it was already off, ran good... until it didn't (1 mowing).

One of the other major differences overall and aside from the carb parts/body being plastic, is the fact they do not bolt on to the intake. The bracket that the filter backing plate bolts on to vibrates along with, but independently of the engine. It'll still allow the carb to vibrate as well.

With the carb relying on an o-ring to provide a seal, just don't think it's doing a good job. With the vibration that occurs, I'm thinking there's enough of a "leak" created to allow any tiny grass clippings to get drawn in, but not necessarily enough of a leak to impact how well the engine runs (until fuel flow gets blocked by debris in the bowl).

 

[Stelth]

Did a search and found this thread. I already knew that California gas station gas would clog up the plastic carb on my Briggs 6 hp string trimmer, the one that looks like a lawn mower. After cleaning it out a couple of times, usually using one wire from a wire brush to push through it, I tried TruFuel 4 stroke gas. Now, no problems with clogging, even after not running it for months.

I was up at my son's house recently, and he said his mower wouldn't start. It's a Craftsman with a B&S engine, only a couple of years old, and he hasn't run it all that much. On removing the air filter assembly, I noticed that it looks like the same carb. I'm not very good with carbs, but these are pretty simple. I took the bowl off, and was able to pull out that white plastic dealio that's in the middle. Same routine, little pressed in brass orifice that I couldn't see light through. Took a little wire brush and stuck it through there, and could see light again. After I put it back together, it started on the first pull. Ran fine, I mowed some of his dry weeds with it.

I told him to get some TruFuel at his local home improvement store. We're in Southern California and don't have big lawns to mow (I'm working on making mine smaller), so even at $20+/gallon, it's not prohibitively expensive.