If there was debris/ water in the tank and lines your new carb is now contaminated. That stuff just doesn't come out w/ draining the gas always. The fuel cap should also be venting. Usually that issue begins after several minutes of running. Is this a model w/ the carb on the fuel tank? #s would be helpful.

Start using fuel cleaner conditioner and a Fuel Stabilizer during extended storage and you will not experience this form of carburetor related gumming issues .

I'm having a similar problem, but I know it's not bad gasoline. Priming the engine or spraying carb cleaner gets it to run until that fuel is burned, but then it shuts down. Cleaned out the carburetor, including all the pin holes in the bowl nut and up through the carb. Then, someone blocked the air intake hole with his finger, cutting off appx 75% of the air, and the engine kept running. Float seems to be working fine, and the carburetor is getting gas. Other than having someone walk along side the lawn mower while I'm cutting the grass, with their finger regulating the air intake, what can I do to keep the engine running? Briggs & Stratton engine, if it helps. Thanks.

It's probably still lean on fuel somewhere. You might be able to use a strong Sea Foam solution in the gas and it will clean out the varnish.

You have not either replaced a plugged fuel filter or have not properly cleaned the carb circuits .

Thank you, baymee and ewalk. By carb circuits I assume you mean the pinholes in the carburetor. For sure I haven't changed the fuel filter. I'll do that, and if it doesn't do the trick, take the carburetor off again and clean it out good. And if still nothing, look for that Sea Foam stuff. Thanks again guys.

I am having the same problems, the lawnmover will start for a few seconds and them stall. Craftsman 917.377 280 Briggs and Stratton engine. This mower is over 10 years and I have not had starting problems at all. It started well at first pull for all these years.

If I have to apply some Sea Foam. What is the proportion and do I put it in the oil or fuel. My manual says oil cap = 20 ozs and Fuel cap is 1.6 qts.

D: Put a few ounces in a fresh fuel system its the carb your attempting to clean !

Looks like there are two threads on the same theme. I posted the following on the other one, but have had no response. This thread seems more current; so perhaps someone monitoring it can help.

RE: Craftsman Lawnmower Won't Stay Running Part 2

Posted by tofino (My Page) on Thu, Aug 12, 10 at 20:00

I have the same problem with a model 917.377822 -- a Briggs and Stratton 7.0 Hp engine. It's run very well for three years, and I've kept it maintained. Oil levels OK and air filter clean. But now after running for a few seconds it dies.
I've tried hilmay's re-priming trick, and as long as the primer is permanently pressed in it runs. But after letting the primer go the engine still dies. I've done this a dozen times.

So, any suggestions about next steps? I'd be happy to take the carb apart and clean it. But the manual isn't helpful in that regard, nor is the schematic that Craftsman posts. Not sure where to start in that disassembly. Is there a better diagram somewhere, and can anyone walk me through the steps? Thanks.

Soved it.

After doing some online search, Realized I probably had to clean the carburator. Did some search on youtube and there are some good postings there.

Basically dismantled the carburator, cleaned it nicely inside out. Just using WD-40 and some compressed air. The carburator was in very good shape for a 12 year old mower. Assembled it and cranked it, It fired up at first shot. Smoked a bit for some time and then looked good. I will test it in a few days when I have to do the lawn, that will be the test.

I also took the opportunity to clean it allround using simple green and hosing it down. The mower now looks like it is 2-3 years old.

Inspect the V-belt to see if it is not stretched. I also filled the gear box with greased.

The instructions are very simple and are on youtube.

I would suggest you drain the fuel so the leak is minimum. You will need small sockets spanners with screw driver attachment.

I have a Craftsman Riding Mower DYT4000, Model # 917.273621. Briggs & Stratton Intek Twin 24 OHV.

Last week it worked like a champ. This week, not so good.

It will start up but when I let the clutch out, it dies. I have tried it in neutral, forward, reverse, deck -up, deck-down, blades engaged and blades off. Doesn't matter.

As soon as I take my foot off the clutch, it turns itself off. Now, if I push the clutch back in, it revs back up.

Any suggestions?

You should post a new thread, but it sounds like a malfunctioning safety switch.

my new Murray (Briggs&Stratton) mulching mower would stall a few seconds after starting. I primed according to the instructions but it would always stall out after running 5 seconds or so. After reading this thread I primed it again after it started. I had to do this a few times but it did continue to run after doing this a few times. I let it run awhile and then turned it off. It started back up without priming and seems to be OK.

Just had a B&S that died after 2 mins when hot. Turned out to be a faulty spark plug. Motto first try plug before looking at fuel starvation. Symptoms can be similar. Plug easier to fix than carb rebuild.

I have the same 7hp briggs/craftsman mower and just ordered a new carb for $30 off Amazon, installed it, cranked up first time...fantastic. Until I put the air filter back on. It runs perfectly until I put the air filter on. The airfilter is nearly new, very clean, the filter housing and gasket are on correctly. Help

Have followed this thread from the beginning without finding a solution to my problem that is the same as the OP. Have a Craftsman Riding Mower 4000 Model # 917.288573 B&S 24 HP.

Finally solved the problem it turned out a defective fuel pump vacuum tube it had a small crack in the rubber this is the tube that goes from the pump to the OH valve cover.

Hope this helps someone. I thought the pump was some fuel eco thing but no.

Try loosening gas cap. If this works replace cap. Vent hole in cap is clogged

Yeah I was voting for gas cap vent myself. Somehow, I ALWAYS starte looking on the exact opposite end from the problem. Its like a dysfunctional superpower. I usually have the vent cap problem or dirty carb jets.

I had the same problem. Then realized that I had not changed the air filter in ages. It was completely clogged. Replaced it and the mower worked fine.

Not Rocket Science normally just common sense , process of elimination as long as you understand the symtoms and know where to start . Just remember the 3 components of any internal combustion engine , Fuel , Ignition and Compression . More or Less of any of the three , and you have a problem lol !

hilmav, Bless you. WE have a relatively new lawnmower and were having a hell of a time keeping it going. We had it serviced several months ago and it worked okay for a couple of months...Today it started and stopped... I was frustrated as I had no idea how to clean the carburetor etc as most people recommended (I also didn't have the tools to do it.) I tried the prime while motor running and eventually it began to stay going and running smoothly. I have a postage sized lawn and is newly mown and a solution to what has been an ongoing issue. THANK YOU

I have a similar problem. It's a self priming mower, one year old. It starts and runs for a second or two and dies. Air filter is clean. Gas cap is good. Suggestions?