Briggs 14.5hp engine running lumpy??

Hi guys, just joined. I've got a Briggs and Stratton 14.5hp engine on my craftsman 42" cut ride one. After cleaning the carb out of some horrible gunk that was blocking the main jet I put it on and it started up. Brilliant I thought. Then it started to run lumpy, like the revs were pulsing.
Engine number is 287707-1259-E1
The fuel supply is fine so I'm thinking either the carb needs adjusting or the governer speed?
one last thing, when I slowed the revs to near tick over in just died, mainly, I think, due to the rising and falling revs.
Thanks
paul

 

Hello, and welcome!

It is surging because there is still a bit of a blockage in the carb. Open it back up and clean it more. Push a wire through the main jet and try to get it open as far as it will go.

 

hi cheese,
thanks for your reply. here is a link to the carb;
Parts and Diagrams for Briggs and Stratton 287707-1272-E1
mines the Nikki carb on the right side of the screen.
i took the carb bulb off and unscrewed the fuel solenoid, i then pushed out a tiny little ring seal in the float which was blocked, i cleaned this up so there was no gunk what so ever left. the fuel i would suspect goes through this ring seal and up towards the top of the carb which i take it then goes through a jet. is this the jet your on about? if so what part in the above diagram is the jet and what number is it so i can locate it and remove it to clean.
the engine was running fine when i last used it so thinking it must be something to do with the gunk i cleared out the other day.
thanks again,
Paul

 

When you remove the bowl, is the inside white plastic or all metal? The main jet is in the long piece that extends down off the bottom of the carb.

 

The float is plastic. I removed a tiny ring of metal that was wedged into the bottom of the float. I pushed it out and cleaned it up. I reckon that was the jet?! I then pushed it back in, slipped the whole plastic float assembly on the carb then screwed it all back together. When I had finished cleaning ther was no dirt left. That's why I was wondering whether some of that gunk had pulled up to the top of the carb? If so it there any more tightish holes the fuel has to go through before hitting the engine?? Thanks again. Paul

 

Okay, it sounds like you have the white plastic body inside the bowl. Nikki Made them a few different ways. On this one, you still have a brass tube extending down off the bottom of the carb body. This has tiny holes in it that may need to be cleaned as well. On the main jet that you removed... it is very sensitive to blockage. Even if you got the hole cleaned out, if there is even just a tiny bit on the inside edges of the hole making the hole just a few thousandths of an inch smaller in diameter, it will surge. I use torch tip cleaners from a welding supply store to clean them so I can get a good cleaner with a tight fit to the hole. They only run about $5 for a set.

 

ok cheese, ill wip it off again and use some brake and clutch cleaner on the shaft that u talk about. i remember now it was a bit scabby with rust so will use a bit of wire or terminal screwdriver to scratch it clean.
one other thing, should the governor speed rod that sits behind the governer plate move while the engine idles? i only ask as when the revs pulse the governor rod moves in time with the revs.
thanks

 

Yes, that's the only reason it is running, the governor is kicking in just before it dies and giving it gas. It's doing its job.

 

Nice. I think the idle needle may still need adjusting though as the engine does cut out rather quickly even when u move the lever from choke/full speed to about half throttle. I'll give it another clean and see how we get on. Cheers

 

Right, I've given it a really good clean and its spotless now. I installed it and it now runs alot smoother. It still has a slight but if pulsing though and u can see the governer moving to stop the engine from stalling. I've done a recording on my phone so was going to post that up when I get a min. There must be something else that is causing the slight pulsing in the revs? Maybe air supply, governor speed out, it the carb needs adjusting???

 

Take the little plastic jet out of the carburetor... the one with the tiny o-ring. Get a set of torch tip cleaners from a welders supply store or home depot or wherever... they are cheap. Find the one that barely fits in the hole in the jet and push it through there and work it back and forth until the cleaner rod fits through easily. Then reassemble and you should be fine.

 

Are these the things you are on about; http://item.mobileweb.ebay.co.uk/vie...w=160808979124

 

Yes, that's the ones.
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Hmmm, well I have cleaned the main jet with the tip cleaners but it has made no change. It's still pulsing in revs with the governor flipping with the pulses?! Anything else you can think of??

 

Did you force the one through that doesn't quite fit?

 

Well I tried all the sizes up to the size that wouldnt fit, I then pushed and it pushed the jet out so I reverted back to the smaller size and filed away till the little brass jet was clean and all I could see was clean brass. There has now got to be something else that's making the revs pulse. I'm going to get a bloke by me to look at it!! Thanks for your help.
Paul

 

Something is still restricted in the carb then.

 

I'm having this same problem with my briggs, did the solution ever get figured out?

I've cleaned the crap out of my main jet with a torch tip cleaner. I adjusted the valves. The only thing I can think of next is dipping the whole carb into a bucket of carb cleaner.

The motor dies at low idle, pulses bad at mid idle and spits at full idle. At mid idle, exhaust blows back out the intake.