B & S engine skips at running speed

nodsirrah · 10-17-2009, 12:04 PM

I have a B & S model #286707 engine on my 1992 Sears lawnmower.
When I run it up to normal operating speed it skips, it runs smoothly at idle. It acts as if I was pulling and replacing the spark plug wire every 1 second.
I have been using it for 17 years and it just started skipping 2 weeks ago.
What should I check?

**Basementgeek** · 10-17-2009, 12:45 PM

Hi and welcome to the forum

Have you tried a new plug ? Plugs can look good but still be bad.

BG

Vatar · 10-17-2009, 01:37 PM

Like BG said change the plug if that doesn't help I would think your coil would be another likely suspect or one of the jets on your carb is clogged and she is starving for fuel if the contacts on the plug look white that means she is running lean and I would rebuild/clean the carb. On the other hand if the plug looks black that could mean its running rich.

nodsirrah · 10-17-2009, 03:04 PM

I replaced the plug, it was really black, that did not help.
Time to check into replacing the coil and rebuilding the carb, it's the least I can do after 17 years of faithful service.
Thanks, Don

**K-B** · 10-17-2009, 03:25 PM

You need to put an inline spark tester on there and see if the spark is skipping. If the spark is skipping, it's ignition/coil issues. If you have a steady spark, then look into fuel related issues.

nodsirrah · 10-17-2009, 05:05 PM

Good suggestion K-B, it would be a lot less costly to replace the magneto assembly than the carburetor. I have no experience with small engine carbs, and at my age replacing the mag should be a lot less strenuous.
I'll have a spark tester next week.

Vatar · 10-19-2009, 07:13 PM

Leave the plug in the wire but out of the engine and see if it is sparking as you turn it over if it doesn't or if it is very weak that's a sign your coil is bad.

nodsirrah · 10-20-2009, 06:45 AM

Is the "Solid State Module" part # ST440433 the same as the "coil"?

**K-B** · 10-20-2009, 11:01 AM

Quote:

Originally Posted by nodsirrah

Is the "Solid State Module" part # ST440433 the same as the "coil"?

Yes, it would be an aftermarket equivalent.

k2skier · 10-20-2009, 02:55 PM

17 years!!! I would look at the valves for sure. the clearance is most likely gone away and the carbon build up will be massive.

nodsirrah · 10-20-2009, 06:18 PM

Where can I download a manual that shows how to adjust the valves? Other than dissassembeling the engine is there a way to decarbon the engine? I can't afford to pay anyone to do the work for me!

k2skier · 10-21-2009, 12:13 PM

Make sure and run it with a spark tester to rule out a misfire.

http://www.briggsandstratton.com/mai...nual_and_more/

nodsirrah · 10-21-2009, 02:37 PM

I just ran the spark test, at high speed with skipping I don't see any missfire, I kept slowing it down and just before it went to idle where it runs smoothly I believe I could just barely see a pause when it was skipping. I will go for the solid state module, it is only about $40.00, if not, I'll go for the carburetor, the module can't be too difficult for an old man to replace.
Wish me luck.
Don

10-17-2009, 12:04 PM	#1 (permalink)
nodsirrah Registered User Join Date: Oct 2009 Posts: 6 OS: XP Home SP-3	B & S engine skips at running speed I have a B & S model #286707 engine on my 1992 Sears lawnmower. When I run it up to normal operating speed it skips, it runs smoothly at idle. It acts as if I was pulling and replacing the spark plug wire every 1 second. I have been using it for 17 years and it just started skipping 2 weeks ago. What should I check? Last edited by nodsirrah; 10-17-2009 at 12:05 PM.

10-17-2009, 12:45 PM	#2 (permalink)
Basementgeek Moderator, Home Support Join Date: Feb 2005 Location: Central Ohio, USA Posts: 1,467 OS: XP Pro SP2/Vista Ultimate SP2 Blog Entries: 3	Re: B & S engine skips at running speed Hi and welcome to the forum Have you tried a new plug ? Plugs can look good but still be bad. BG __________________ Donating to the forum keeps TSF free for all. Proud member of ASAP

10-17-2009, 01:37 PM	#3 (permalink)
Vatar Registered User Join Date: Oct 2009 Posts: 26 OS: 2000 Professional	Re: B & S engine skips at running speed Like BG said change the plug if that doesn't help I would think your coil would be another likely suspect or one of the jets on your carb is clogged and she is starving for fuel if the contacts on the plug look white that means she is running lean and I would rebuild/clean the carb. On the other hand if the plug looks black that could mean its running rich. Last edited by Vatar; 10-17-2009 at 01:40 PM.

10-17-2009, 03:04 PM	#4 (permalink)
nodsirrah Registered User Join Date: Oct 2009 Posts: 6 OS: XP Home SP-3	Re: B & S engine skips at running speed I replaced the plug, it was really black, that did not help. Time to check into replacing the coil and rebuilding the carb, it's the least I can do after 17 years of faithful service. Thanks, Don

10-17-2009, 03:25 PM	#5 (permalink)
K-B Moderator, Linux Join Date: Oct 2005 Location: NY Posts: 2,873 OS: Vista, Ubuntu My System	Re: B & S engine skips at running speed You need to put an inline spark tester on there and see if the spark is skipping. If the spark is skipping, it's ignition/coil issues. If you have a steady spark, then look into fuel related issues. __________________

10-17-2009, 05:05 PM	#6 (permalink)
nodsirrah Registered User Join Date: Oct 2009 Posts: 6 OS: XP Home SP-3	Re: B & S engine skips at running speed Good suggestion K-B, it would be a lot less costly to replace the magneto assembly than the carburetor. I have no experience with small engine carbs, and at my age replacing the mag should be a lot less strenuous. I'll have a spark tester next week.

10-19-2009, 07:13 PM	#7 (permalink)
Vatar Registered User Join Date: Oct 2009 Posts: 26 OS: 2000 Professional	Re: B & S engine skips at running speed Leave the plug in the wire but out of the engine and see if it is sparking as you turn it over if it doesn't or if it is very weak that's a sign your coil is bad.

10-20-2009, 06:45 AM	#8 (permalink)
nodsirrah Registered User Join Date: Oct 2009 Posts: 6 OS: XP Home SP-3	Re: B & S engine skips at running speed Is the "Solid State Module" part # ST440433 the same as the "coil"?

10-20-2009, 02:55 PM	#10 (permalink)
k2skier Registered User Join Date: Sep 2008 Location: Oregon Posts: 313 OS: XP Home-SP3 My System	Re: B & S engine skips at running speed 17 years!!! I would look at the valves for sure. the clearance is most likely gone away and the carbon build up will be massive.

10-20-2009, 06:18 PM	#11 (permalink)
nodsirrah Registered User Join Date: Oct 2009 Posts: 6 OS: XP Home SP-3	Re: B & S engine skips at running speed Where can I download a manual that shows how to adjust the valves? Other than dissassembeling the engine is there a way to decarbon the engine? I can't afford to pay anyone to do the work for me!

10-21-2009, 12:13 PM	#12 (permalink)
k2skier Registered User Join Date: Sep 2008 Location: Oregon Posts: 313 OS: XP Home-SP3 My System	Re: B & S engine skips at running speed Make sure and run it with a spark tester to rule out a misfire. http://www.briggsandstratton.com/mai...nual_and_more/

10-21-2009, 02:37 PM	#13 (permalink)
nodsirrah Registered User Join Date: Oct 2009 Posts: 6 OS: XP Home SP-3	Re: B & S engine skips at running speed I just ran the spark test, at high speed with skipping I don't see any missfire, I kept slowing it down and just before it went to idle where it runs smoothly I believe I could just barely see a pause when it was skipping. I will go for the solid state module, it is only about $40.00, if not, I'll go for the carburetor, the module can't be too difficult for an old man to replace. Wish me luck. Don