18hp starts, runs 2-5 min, dies, restarts, over & over

Craftsman riding mower, B&S 18hp Intek. No fuel pump. ABout 11 years old. I bought it new and it has given me zero problems up to now. Well-maintained throughout its life. While mowing a few days ago, it just sputtered and died. Would restart and sputter for a few seconds and die. At that time, I pulled the gas line off the carb and gas was flowing. Hooked it back up and it started, ran a couple minutes, die. Would restart and sputter. Then would restart and run a minute or two. Then restart and sputter. etc. It seemed if I removed the gas line and then hooked it back up that it would run longer. But maybe one time out of ten. Removed the carb and sprayed it all out and reinstalled. Changed the air filter and fuel filter. SAme results as before. Gave up and read some forums.

Each morning, I would go out and start it. it would run 2-5 minutes, then sputter & die. Then restart & sputter & die. I tried this both with the gas cap on and gas cap off. Also with the gas cap partially on. No difference. If it sat overnight, it would do the same thing the next morning. STart, run 2-5 minutes, restart, sputter, die, restart, sputter, die. Gave up and read some more forums.

So this morning, I took the carb back off, cleaned out every orifice with a small wire, Sprayed carb cleaner in every orifice. Even sprayed WD-40 in them (because it had a thin tube so I could get more pressure) then followed up with more carb cleaner. Got good spray out the other side of the holes, cleaned and sprayed the carb inside and out within an inch of its life. ABout a half of a can of carb cleaner used. Checked the solenoid on the bottom of the carb bowl. It activates when the key is turned on. Put carb back on and......no change from previous days, other than it now would have to sit a shorter amount of time in order to restart - hour or so vs. overnight. Ugh. Replaced the spark plug. And now its getting a little better. (old plug was light brown & looked fine, but I replaced anyway) It will now start, run for 2-5 minutes, sputter & die, restart immediately, run 2-5 minutes, sputter & die, repeat. I repeated this cycle five times. One time with gas cap on, one time off, one time with the idle mixture adjustment screw turned to the left, one time with it turned to the right (there is a limiter so it will only turn 1/2 turn in either direction), then one more time with it in the middle. No change. It always starts right back up immediately now after sputtering & dying. Sometimes if I pump the speed control from "mow" to "choke", I can coax it to run sputteringly 15-30 seconds longer. Gas level at any time in the clear fuel filter is about 1/3 whether sitting, running, or having recently died.

This is making me nuts. Help!

Maybe the engine runs long enough to warm the ignition up then you are losing spark. just something else you might check seeing are getting a good fuel flow.

Thank you for the reply. I don't think its an ignition problem, because it immediately starts right back up. I just now ran through the five-times cycle. First time it ran for four minutes, then two, then one, one, and one. Each time it immediately fires right back up and runs fine right after dying. Fuel level in the fuel filter is more like the 1/4 level at all times once I got looking closer at it.

Post model number from under seat as well as all numbers from engine data plate. Also check your fuel lines for cracks, etc.

No fuel pump. Some of the Briggs engines have the fuel pump built into the carburetor. I don't know what you have. As far as the filter only being 1/4 full of gas I find that can be normal. Fuel line is cheap replace it if it is 11 years old.

There's not a fuel pump in the carb. Just fuel line straight from the tank to the fuel filter, then fuel line to the carb. When I had it all apart, I could see there was no pump. I think fuel line is fine, as when I disconnect from the carb, gas literally gushes out. But I'll pick some up tonight and give it a try.

Tractor is Craftsman model # 917.273396

Numbers on the engine (on the top of valve cover) are: Model 3P777 Type 0299E1 Code 0405077E

Those are the only numbers I could find.

Numbers on the carb: 697216 GO2703 3Y17N

Any help you can provide is much appreciated!

Update. Right before my last post, after it had sat for a couple hours, I started it again and it ran for 30 minutes. Sputtered or "missed" a few times, but other than that, it ran strong for 30 minutes. I decided to move to the next step and put it under load by engaging the blades. It ran for about 3 minutes with the blades engaged then died. STarted right back up, engaged the blades, ran for a minute, then died again. So I started it right back up and it ran for 10 minutes and is still running right at this moment.

So....minor improvement. At least the silly thing will run for a while. Guess I could drive it around the yard and mash the grass down. Still it seems to me that it is getting starved for gas. Is there anything to rebuild or replace carb-wise other than just cleaning it?

Also - I looked over the fuel lines. No cracks, no leaks, all looks good.

Does this carb have the fuel solenoid with plastic cap on the end. If so gently try to pull the cap off the plunger. there is cases where the cap will come off and shut off the fuel, and will restart normally after turning the key off and back on.

jeffnsusan123 said:

Update. Right before my last post, after it had sat for a couple hours, I started it again and it ran for 30 minutes. Sputtered or "missed" a few times, but other than that, it ran strong for 30 minutes. I decided to move to the next step and put it under load by engaging the blades. It ran for about 3 minutes with the blades engaged then died. STarted right back up, engaged the blades, ran for a minute, then died again. So I started it right back up and it ran for 10 minutes and is still running right at this moment.

So....minor improvement. At least the silly thing will run for a while. Guess I could drive it around the yard and mash the grass down. Still it seems to me that it is getting starved for gas. Is there anything to rebuild or replace carb-wise other than just cleaning it?

Also - I looked over the fuel lines. No cracks, no leaks, all looks good.

Click to expand...

The fuel lines can separate and collapse on the inside...do they look OK on the inside?

ILENGINE - are you talking about inside the bowl - the plastic cap that is there? I do recall a plastic cap there attached to the solenoid that would go up & down about 1/2" or so when I turn the key on or off. Isn't it supposed to seal against something to either stop the flow of gas when the engine is not running or allow the flow of gas when it is running? Won't removing the cap defeat that purpose? Or are you talking about a different plastic cap altogether?


I haven't had a chance to get new fuel line to try that, but based on the gas flow when I disconnect it, it seems to be fine. Going to replace it anyway tomorrow just to be sure. Just haven't had a chance today to get to the parts store. I haven't seen any black gunk or pieces or the like coming out of it that would indicate interior breakdown. But I'm still going to replace and will report back.

Since my last post (when the engine was running at the time), it ran for another 20 minutes. I then engaged the blades and it died within a minute or two. Restarted & ran, then blade engage killed it again within a minute or two. Tried same thing a third time.

Just now, I started it again (it has sat for about 3 hours). And things have gone back a step. Back to the 2-5 minutes running time between sputtering & dying. Always starts right back up, though. At any point, engaging the blades will kill it within 30-60 seconds. I had another suggestion to remove the idle mixture limiter piece and turn it counter-clockwise another 1/8 turn to rich the mixture a little. No change. Tried 1/4 turn, then 1/2 turn past the normal counter-clockwise stop point. No change. So I moved it back to factory position and reinstalled the limiter piece.