Garage Sale mower runs but dies after a short time

[Coprolite]

I have an old 625 B&S Craftsman 21" mower. This spring, one of the wheels pulled a little free of the deck and I repaired it with repair plates, screws, nuts and left over pool putty. Given that it is 8 or 9 years old and is used 10 months a year, it has worked hard but the engine runs great. I run stabil in the fuel at about 1 oz per 2+ gallons with an occasional dash of techron when the cars get their dose. I have been facing the unavoidable death or complete overhaul of all the wheels and deck. I have replaced some as they broke, but they all now seem to wobble enough that the mow can seem uneven to the OCD eye. As a result, I jumped at a neighborhood garage sale mower with similar yet newer 675 with no priming and the easy start system. Most of the parts seem interchangeable with the current motor. The family just moved into the neighborhood and decided to use a lawn service, as the husband had only used the mower a few times in the last house and this lawn is much bigger. They supposedly ran it dry on a regular basis. Condition of the mower: cosmetically quite new. under deck surface corrosion due to storing not so well cleaned in a humid Texas garage. Oil is pretty new looking (supposedly only ran about 3 times total since new). Air filter had minor grass in the pleats that has been cleaned out. Plug not excessively fouled. I poured in my usual gas formula and it ran unevenly for maybe 30 minutes and then died. I had on my noise cancelling headphones, so I could tell the sound output was uneven and seemed to be more low key/ low rpm than my regular mower noise. I swapped plugs and finished the lawn with my old mower with the new mower spark plug. The change in plug had no impact on the dead mower. Fast forward to this weekend. This morning I pulled the carb and scrubbed out the dried up varnish with carb cleaner and used a paper clip and the carb cleaner spray tube to get all the small orifices clean. Upon reinstall and adding new fuel, I got it to start after a good number of pulls. It seems to run a bit faster, but with then start to hesitate and the run quality deteriorates until it can maintain running and dies from start to finish is about 40+ seconds. Even when running full bore, it seems to run rough, vibrating the handle... The gas cap seemed like it wasn't the original so I swapped with my old mower which enabled me to get it started but won't let it stay running. What should I check next? This is the first carb that I have cleaned in about 15+ years and the first on a mower. My current one runs great, so I never had to do any serious maintenance outside of changing oil and running a little more fuel treatment if the running deteriorated at all... The worst case scenario involves a quick motor swap and selling the remains on CL to someone willing to fix it or simply returning it to the original owners. He made the comment to let him know if it had trouble running, either due to long period in storage or it didn't run so well when he used it last...

 

[aquariuscsm]

The one time I had a mower that did that (Lawn Boy),all it needed was a new air filter. It'd start on the first pull,run for a few minutes,then die. I replaced the air filter and it never died again.

 

[Fastcompany]

I'd just swap engines. I got one easy start system a Kohler that fires first pull and runs great my Briggs takes five or more then runs good. Not completely sold on the easy start. Never had a problem ever starting something with a manual choke. [censored] I don't like the electric choke on cars either but to often I put them on because people are dumb. But if you would like to keep your engine look at the chick and throttle off the governor. Make sure springs are in place with proper tension and make sure that when running the choke is pulling off. May need to run it without covers in place to verify.

 

[raytseng]

i have a craftsman mower in similar 10years no service. i treated fuel with redline si1, new air filter and that solved the issue for me. mine was also lugging during cutting, but nee vlade was the resolution for that.

 

[ET16]

Did take the bowl off the carb and clean it out? Have you adjusted the mixture screw?

 

[Coprolite]

I removed the carb and cleaned all the parts. I reassembled and sprayed more as I went to reduce introduced debris. After the first few times that it died, I took off the air filter and ran it unfiltered... it didn't die so I ran it for 5 minutes. I put everything completely back on and it seems to run fine now. Not as well as the old one, but it is still on the break in cycle. I will be going full syn when I change the oil. I have a few quarts of leftover PUP to use up. I figure any remaining crud will make it through the system over the coming weeks as the fuel sits in the tank and soaks the carb. Now I just need to sell the old one on CL to defray the acquisition price of the new one.

 

[ffgb]

Go to the Home Depot and buy a couple of bottles of "Mechanic in a Bottle". I had the same conditions as you. I replaced the air filter, the fuel filter, and the spark plug, but it kept dying after a short period of time. "Mechanic in a Bottle" was recommended to me from the an actual lawnmower/chainsaw service center. The technician told me that the ethanol in the fuel causes a lot of gumming in the fuel system and that is why my lawnmower would stop running. I used one bottle in with the fuel. The lawnmower would still stop running but I did notice that it started to take longer and longer for the lawnmower to stop running. Eventually, "Mechanic in a Bottle" totally fixed my problem!!! Now, I buy Flex Fuel in a container from Home Depot, it is 100% gas without ethanol. I also put some PEA cleaner in with the gas in the lawnmower to constantly clean the fuel system and I have never had a problem since!!!

 

[Coprolite]

I have used E10 in my mower since I bought it. This new one was probably run 2-3 times with long intervals in between, so the remnant fuel has coated everything with a nice gummy crud even though the guy said he ran it dry each time. I think my cleaning efforts have done enough, but this is an excuse to try some Berryman's in my car and in the mower. I do run Stabil with carb cleaner and a touch of PEA and the long term mower motor runs like a champ. It was only getting a little creaky in all the other places so I decided to get this one that will live longer...

Originally Posted By: ffgb

Go to the Home Depot and buy a couple of bottles of "Mechanic in a Bottle". I had the same conditions as you. I replaced the air filter, the fuel filter, and the spark plug, but it kept dying after a short period of time. "Mechanic in a Bottle" was recommended to me from the an actual lawnmower/chainsaw service center. The technician told me that the ethanol in the fuel causes a lot of gumming in the fuel system and that is why my lawnmower would stop running. I used one bottle in with the fuel. The lawnmower would still stop running but I did notice that it started to take longer and longer for the lawnmower to stop running. Eventually, "Mechanic in a Bottle" totally fixed my problem!!! Now, I buy Flex Fuel in a container from Home Depot, it is 100% gas without ethanol. I also put some PEA cleaner in with the gas in the lawnmower to constantly clean the fuel system and I have never had a problem since!!!

 

[bubbatime]

A brand new carburetor cost about $14-$20 on eBay or Amazon. You can swap out the entire thing in less than 5 minutes, and it will run like new. The Chinese clone carburetors are very good. Ive used dozens of them and have not had any problems. And they are cheap. Don't waste any more time cleaning it, or spending money on "mechanic in a bottle" nonsense, replace the carburetor. There is a certain satisfaction to spending less than $20 on a part, replacing that part, and seeing that the engine runs like brand new afterwards. Or you could continue spending hours soaking and cleaning a carb that will never run tight. Any more questions? Here is some advice for future reference. Find out the replacement cost of a carburetor, BEFORE you do anything. If its $100, rebuild it. If its $30 or under, replace it. A rebuild kit will set you back $15, and that is still no guarantee that it will work after spending hours cleaning.

 

[Coprolite]

Interesting point of view Bubba. It now runs fine. The mechanic in a bottle would be for BITOG fun purposes. I could probably swap the engines and sell the newer yet questionable one for free and not take much time, with no need to research which carb, order it and then install it. The older mower runs like a champ. Following my practices, it would probably outlast countless cheaply made decks that accompany these entry level machines. I consider it a mini victory that an entry level machine has lasted as long as it has under "heavy" use(e.g. TX vs NY). Using the carb cleaner was quick and easy and pretty much brainless. If I had found anything questionable in the carb, I would have replaced it over messing with the adjustments or try a rebuild kit. As it was basically a brand new machine, I figured the only thing I would find wrong in the thing was the gummed up fuel. In the end, the work took probably saved me time as I didn't have to figure out which carb to buy, especially as the carb was only the suspected issue. The history wasn't known to be and while the symptoms seemed straight forward, I couldn't assume things like the spark were in spec. In the modern throw away mentality society we live in, it is nice to restore something to working status again without throwing half of it away.