8 H P B&S ?

Thu Apr 29, 2004 10:19 pm

I have a 8HP B&S Industrial /Commercial engine on a troy built rotor tiller it starts very easy & runs well. for one row then dies, its starts right back up runs for one row and dies. if i can catch it when its starting to die and hit it with full choke i can keep it running but as soon as i let off of the choke it dies. I Have messed with the float level with no luck have try ed another mag same thing. its like the needle is sticking closed when its running but open once it quits. drain and flushed the tank blew out and replaced the fuel line
any ideas of what to try next???

Thu Apr 29, 2004 10:46 pm

Repalce the spark plug and check the vent holes in the gas cap.

Thu Apr 29, 2004 10:46 pm


Is the fuel tank getting the proper venting :?: :?:

Thu Apr 29, 2004 10:47 pm

I think you should take the carb apart and use a small wire & air to clean all the jets. Also get a can of spray-can carb cleaner with the straw nozzle to blow out the innards good. I have good luck with Wal-Marts brand. It`s cheap. ALSO make sure the float does not have any gas in it.

Thu Apr 29, 2004 11:17 pm

John New plug today vent is open and have even loosen it

Donny ditto on venting tank

johnbron carb has been off 6 times each time it get carb cleaner and have picked at all the jets blown out with air compressor no gas in the float had a new needle and seat last season.

I have use this same tank to run the the cubs when i have the hood off

after almost 40 years ( GOT my first field car at 11) of driving junk and owning second hand equipment it shouldn't be this hard!!

Fri Apr 30, 2004 12:23 am

:roll: Well Hmm!, Sounds like you have pretty much done did it all a few times over but I still think it has a partially blocked jet or passage in the carb. It is definitely a fuel related starving problem because you can stop it from dying by pulling the choke when it starts to quit. :?: :?: :?:

Fri Apr 30, 2004 6:21 am

I have been watching Dogman's thread here with a lot of interest. I have a 6 hp B&S on my roto-tiller and it does the very same thing.

I have cleaned the jets, carb, adjusted the float to specs in the manual and replaced needle and seat. Cap is vented properly as well. New plugs, new coil :!: and coil wire, clean gas, clean tank, and just about anything else I could suspect including the air breather :?

I have the same results as Dogman. And he is right. Nothing should be this frustrating.....

Fri Apr 30, 2004 8:20 am

Dogman, I know this may sound strange, but have you checked to make sure you have fire at the sparkplug when it quits? I've never fought this particular problem on a small engine, but a bad coil on a cub will sometimes give similiar results. Might try changing the condenser, or if it is a breakerless ignition, try changing the module.

Fri Apr 30, 2004 8:37 am

John I change out the module yesterday with no luck checked the kill wire for bare spots and even put new connections on IT.

been scratching my head so much on this one its bleeding

Fri Apr 30, 2004 8:49 am

Well yoose guys, When Dogman started this thread his initial post says.

Quote: if i can catch it when its starting to die and hit it with full choke i can keep it running but as soon as i let off of the choke it dies.

That symptom right there alone tells me it is not an ignition/electrical problem.

Fri Apr 30, 2004 12:04 pm

I know this will sound silly to most of you, but trust me... check the exhaust valve clearance.

Here's what may be happening... After running hard on one row, the exhaust valve gets hot and expands, reducing the clearance to less than zero, just enough to lose much of the compression... which is made up for with the richer mixture. When it has cooled for a short while, compression returns to normal.

Another way to check for the same thing, see how much longer it will run at a slower speed and lower temperature.


Fri Apr 30, 2004 12:20 pm


You just may have something there by gum :!: If I let it idle it will run for hours or until the gas is all used up. And also, as you indicated at the end of the row, say 150 feet or so, that is when it wants to quit. If I give it more choke then it will run, although at reduced capacity. I have to let it sit for a few minutes idleing and then it will go back up the other row.

I will have to check the exhaust valve :idea:

Fri Apr 30, 2004 2:15 pm

Neighbor went over every thing I did then convinced me it the vales it on the bench apart as we speak awaiting rebuild kit well let you know when it goes back together if it works thanks for all the help and support

George you the man Nothing you say sound silly if you told me cub were green under the red I would believe you

Fri Apr 30, 2004 7:54 pm

Dogman wrote:George you the man Nothing you say sound silly if you told me cub were green under the red I would believe you

I've see quite a few that were green over the red, saw one today in fact. It was only on the north side.

Mon May 03, 2004 7:34 pm

Valve clearance on a B&S should be about .006-.010 cold, if it's too tight, grind a little off the end with a bench grinder. Like George,, BTDT. :lol: