Briggs & Stratton 5.5 with plastic carb stalling issues

Z

ZZman

Joined
Mar 17, 2008
Messages
8,334
Location
Michigan
Been having problems with my push mower running fine and then stalling. Been taking the float bowl off and running a pin into the jet and then carb cleaner. Works fine for a while then acts up again. Today I put a fuel filter in the line but the 75 micron filtering ability make me wonder if it still might plug up.

I watched a YouTube video of a guy cleaning the same carb and mentioning how easy they clog up. His solution was a micro drill bit to make the jet opening a little bigger.

https://youtu.be/eGF_ynkc3C0
 
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I got my neighbors mower working and their mower had one of these carbs. The fuel had water in it and there was debris in the cartridge. Fresh fuel and a thorough cleaning of the carb got that little thing to running better than it did when new.

It's a very simple procedure performed just as the video shows. I didn't mess with changing passage sizes though. I simply cleaned everything, ensured all ports were open and then I put it all back together. It ran better than new.

This was two years ago and I hear that little thing running every few weeks next door. I told them to use ethanol-free fuel and keep it inside when not being used and that seems to done the trick.
 
Originally Posted by Lubener
If you have been doing this repeatedly, why not clean the tank out also?


I don't know. Either I am lazy, stupid or a combo of both. I might just just have to do that too.
 
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Originally Posted by Lubener
If you have been doing this repeatedly, why not clean the tank out also?

Which is why I keep a paint Brush handy for cleaning around the Cap 'before' removing.
 
Runs good for a minute or so then falters and stalls is starving for gas from the tank. If the main jet is clogged it will never run right from the start. How fast does gas come out of the tank line when you disconnect it from the carb?
 
The tank has to be spotless, period. Some people I know use paint strainer funnels when refueling because of trash in the fuel. IDK......
 
Originally Posted by mk378
Runs good for a minute or so then falters and stalls is starving for gas from the tank. If the main jet is clogged it will never run right from the start. How fast does gas come out of the tank line when you disconnect it from the carb?


It will run good for a while then stall. Then it will start and stall almost immediately or not start at all.

Flow from tank appears really good when I was doing the work of putting the fuel filter in the line.
 
IMO Berryman's B12 is like $3.12 at Walmart and helps dissolve gum and other nasties in fuel that sits awhile. Whenever I fill up my OPE gas can, I dump in a couple ounces of B12 and shake it up. I've never had to take apart any carb on any of my OPE. Change filter every spring, they're like what, $2-3?
 
One more simple thing to try is to loosen the gas cap when it starts to stall. If it keeps running after that, the vent in the cap is plugged.

L8R,
Matt
 
Originally Posted by perfect_oil
Try drilling out the jet with a 0.020'' drill bit like the guy in the video says to.

Why? Using a wire there is less chance for damage.. . Common sense tells me if there is junk upstream from the carb and you clean it up, the problem will be solved.
I have found some carb cleaners are engineered for automotive use with metals and not designed for plastic and can damage it. Ether or instant start works great and will not damage plastic.
 
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If you really want to clean the jets out, get yourself a set of torch tip cleaners. Just go easy and no damage will occur.

Torch Tip Cleaner

[Linked Image]



L8R,
Matt
 
Originally Posted by ZZman
Originally Posted by mk378
Runs good for a minute or so then falters and stalls is starving for gas from the tank. If the main jet is clogged it will never run right from the start. How fast does gas come out of the tank line when you disconnect it from the carb?


It will run good for a while then stall. Then it will start and stall almost immediately or not start at all.

Flow from tank appears really good when I was doing the work of putting the fuel filter in the line.


I just mail-ordered one of these carbs off eBay for a family member's briggs powered push mower. $13.65 shipped.

Same scenario. Mower will start, run for maybe 5sec and stall. I can keep it running by hand choking it. The carb that is. Mower sat for 2-3yrs with fuel in it.
 
Originally Posted by Lubener
Why? Using a wire there is less chance for damage.. . Common sense tells me if there is junk upstream from the carb and you clean it up, the problem will be solved.
I have found some carb cleaners are engineered for automotive use with metals and not designed for plastic and can damage it. Ether or instant start works great and will not damage plastic.


He made a pretty good case for the stock jet being way undersized; so undersized that it clogs up with even clean fuel. The jet in the lady's mower kept getting clogged up until he decided to go oversize to 0.020''. After he did that, the mower ran fine and the lady never brought it back. He even asked the lady to please bring it back because he wanted to know if it got clogged again. He says that most Briggs & Stratton carbs have a 0.028'' size jet, so going to 0.020'' is not too outlandish. He never did figure out what the jet was getting clogged with. He made sure the tank and the fuel was clean.
 
One thing I didn't see mentioned in the u-toob videos on this particular briggs plastic carb is in regards to the choke linkage. What I've found with the cheap mail-order replacements is they don't come with the linkage piece for the choke. You have to carefully pry it off the original carb and fit it onto the replacement. it snaps (sometimes HARD) onto the stub/shaft.

As cheaply made as these OHV briggs ~150cc engines are, they sure are easy to work on. 3 simple bolts on the engine shroud and the whole shroud-recoil assembly lifts right off.
 
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My mower developed this problem after 4 years of ownership.
I've only used non-Ethanol gas. I add fuel stabilizer during winter storage.

I disassembled the carb and cleaned it with carb cleaner. Honestly, it looked clean as a whistle inside, but I still went ahead and cleaned the jets and blew it out with compressed air. I dumped the gas tank and cleaned it with carb cleaner. It also looked pristine inside, but I wanted to be sure.

After reassembly, the engine still acted like it was starved for gas. Even after it was fully warmed up, I had to manually hold the choke closed in order to keep it from stalling.

I decided to follow the advice at and enlarge the main jet. I disassembled the carb a second time, reamed the jet with a 0.5mm drill bit, installed a fuel filter, and reassembled everything.

It started on the first pull and runs like new.

Honestly, that carb looked perfect after my first cleaning. But reaming the jet made all the difference.
 
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