Briggs Quantum multple problems

[ebk]

Hi everyone, I am new to this forum, but so far your posts have helped with multiple issues that I have encountered so far.

Let me back-up. I have a Briggs and Stratton 5 HP Quantum engine in a MTD frame circa 1994. It was left idle for over 10 years. I tried to resurrect it, but to no avail. I then looked at spark and fuel, both were a problem. I replaced the plug with a new one from B&S and it turns out, believe it not, that the plug was defective, i.e., maximum resistance between the terminal and the central electrode. So, this compounded my identification of one of the issues. I initially thought it was the magneto and bought a new one, only to figure out that the real problem was the spark plug, ugh! Next on to the fuel. I purchased a rebuild kit for the carburetor overhaul kit. Needless to say, after 10+ years of sitting, the carburetor was a mess. Lots of crud and corrosion in it clogging up everything, e.g., jets, etc.. So I cleaned as best I could and replaced gaskets, needle and seat, air mixture needle. and Walbro plugs. I can tell you that the OEM kit is not of the same quality that the original was. So after taking it apart three times due primarily to new crud and old crud clogging up some very small openings and the small jet that I had missed. I have also realized that the needle seat is screwed up, partly my fault due to bad eyesight and flimsy new seat. I should have kept the old one in. The current issue is that the mower stalls after a just a few minutes of heavy use and gas overflows out of the front of the carburetor. So. I was thinking that it was debris clogging one of the jets, but the overflow tells me that needle and seat are not sealing. Ordered a new non-oem carb overhaul kit and in the mean-time I will try to create my own seat out of gasket material. Do you think that I am on the right track? Also, the flywheel magnets exhibit different strength from one side to the other, and it sometimes misses every other ignition. I know it's time to get a new mower but I can't afford it right now. Any and all suggestions would be greatly appreciated. P.S. A new flywheel is in the $60 to $70 range, which I would rather put towards a new mower. I've checked a couple of places nearby to see if they could remagnetize the existing flywheel, but it seems like this is a lost art.

Thanks for your attention and in advance for your help!

 

[DaveTN]

Welcome to LMF! Don't think you'll have much luck trying to make your own needle / inlet seat. They're just rubber pieces with a hole in the middle that press in. I think you said you put in a new needle, but you need a new seat to go with it. I'd get the old seat out, clean the whole carburetor in a chemical bath. Otherwise you'll be getting tiny pieces of crud in that carburetor down the road. After all that work spraying, etc..it's just not worth being aggravated when you need the mower most during use. If you're getting fire I wouldn't get a new flywheel. I rarely replace a flywheel on engines unless they're heavily damaged or cracked etc. Don't despair, I've resurrected mowers in worse shape than yours from the brink that had been given up for the bone yard!

 

[ebk]

Thanks for your advice, DaveTN!

You were spot on. My effort to create a new inlet seat was a joke. The one in there was from a overhaul kit, but I buggered it up when I put it in. I didn't realize that it was as tricky as it was and that the new seat was so delicate. This time, I used my glasses and lots of light to get it in properly.

Although I was getting a visible spark, I guess it wasn't strong enough. Many times, I was getting just every other ignition. So I had assumed it was the flywheel, which showed lower magnetism on one side. So, I looked into the new flywheel, but the cost was more than the mower was worth. As a last ditch effort, I decided to replace the magneto. That did the trick.

Unfortunately, I didn't do the chemical bath. I guess there's a liquid version of Gumout that I could let it sit in for a while. However, I'm not certain whether it will take off the varnish like buildup, as the spray didn't seem to have an impact on it. Any advice or recommendations on this? So, it seems to be running OK right now. However, I guess it's just a matter of time before that corrosion and varnish will clogs things up again, especially since some pf those holes and jets are super small.

Thanks for your recommendations and for responding.

 

[DaveTN]

I use a flat punch that will slide the seat in squarely until it bottoms out. I had a Sears riding mower just last week that was leaking gasoline down into the cylinder. Wound up being some little piece of foreign material over the seat not letting the float needle close. Removed float and needle and carb inlet hose. Just blew carburetor cleaner up through the rubber seat and out the fuel inlet going into the carb. That "L" shaped fitting. Some small bit of dirt, varnish or something blew out and that fixed it. It doesn't take much to cause a big problem in a small engine! Glad you're back on line w/ your mower and happy to be of help.

 

[lawn mower fanatic]

I moved your thread to the Small Engine & Mower Repair Forum. :smile: