Engine Stops Dead: More Fun With the Briggs

8 HP B&S engine on my 4.4 kW generator. Vintage 1992. Low hours for its age. The carb is an updraft type with a round fuel bowl surrounding the barrel.
I've had more issues with this one B&S engine (mostly carb) than a lifetime of Tecumseh.
Engine starts and runs. Some hunting but I think a new governor spring will help that and/or futzing with that fine spring that is wrapped around the linkage wire which I guess takes up any tiny amount of play.
But it stops after about 3 minutes. Can restart easily but stops again a few minutes later each time.
Assuming it's not a mysterious ignition failure, it's being starved for fuel. But why? It's not actual flow of fuel...disconnecting the hose, it runs out fine. I previously thought it was the fact that I cannot see how air can get into the fuel tank and was considering making a pinhole but running the engine with the tank moved away a bit so the cap can be left off entirely (@ normal height) produced the same cuttoffs so it's not that.
I did get a carb kit a few years back and replaced the various parts. I've always had issues of seepage where the bowl fits together and I've always made sure the surfaces were polished clean, used a new gasket, gasket plus Permatex, or Permatex alone. Someone suggested that the fuel level in the bowl was simply too high so on the last go-round I bent the tab on the float to shut the valve sooner. So that is one possibility-- that the flow is less than consumption and it just runs out of gas until the bowl is replenished.
Another thought is whether there is some sort of air vent into the bowl that is clogged. It's true that I don't totally understand the various passages in this carb. Like on the underside, near the intake, there is an opening that is filled with copper-colored metal granuals, sort of like some auto fuel filters. I don't know if that requires cleaning.
My most recent assembly of the bowl involved 2-part epoxy so it will be a bear to open and clean that off but at least there's no more seepage. If I do go back in and apparently I must, I'd like to make it count.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
One other option, is valve clearance. It's tough to explain in text. I'll try and find a web page that can explain better than I.
http://wiki.answers.com/Q/How_do_you_check_valve_clearance_on_Briggs_Straton_14.5_hp_eng This is less than useful. Buy the manual, it says.
Wish I could find a good web page.
Christopher A. Young Learn more about Jesus www.lds.org .
8 HP B&S engine on my 4.4 kW generator. Vintage 1992. Low hours for its age. The carb is an updraft type with a round fuel bowl surrounding the barrel.
I've had more issues with this one B&S engine (mostly carb) than a lifetime of Tecumseh.
Engine starts and runs. Some hunting but I think a new governor spring will help that and/or futzing with that fine spring that is wrapped around the linkage wire which I guess takes up any tiny amount of play.
But it stops after about 3 minutes. Can restart easily but stops again a few minutes later each time.
Assuming it's not a mysterious ignition failure, it's being starved for fuel. But why? It's not actual flow of fuel...disconnecting the hose, it runs out fine. I previously thought it was the fact that I cannot see how air can get into the fuel tank and was considering making a pinhole but running the engine with the tank moved away a bit so the cap can be left off entirely (@ normal height) produced the same cuttoffs so it's not that.
I did get a carb kit a few years back and replaced the various parts. I've always had issues of seepage where the bowl fits together and I've always made sure the surfaces were polished clean, used a new gasket, gasket plus Permatex, or Permatex alone. Someone suggested that the fuel level in the bowl was simply too high so on the last go-round I bent the tab on the float to shut the valve sooner. So that is one possibility-- that the flow is less than consumption and it just runs out of gas until the bowl is replenished.
Another thought is whether there is some sort of air vent into the bowl that is clogged. It's true that I don't totally understand the various passages in this carb. Like on the underside, near the intake, there is an opening that is filled with copper-colored metal granuals, sort of like some auto fuel filters. I don't know if that requires cleaning.
My most recent assembly of the bowl involved 2-part epoxy so it will be a bear to open and clean that off but at least there's no more seepage. If I do go back in and apparently I must, I'd like to make it count.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Hmm...that's interesting. That could cause it to just suddenly stop as though I'd turned off the fuel flow?
A can tell you that when it runs, it sounds okay other than the hunting and if I hold the throttle valve steady to prevent the hunting then it sounds very good. I could be wrong but I still believe fuel starvation.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 05 Dec 2012 17:52:30 -0600, Steve Kraus

It'll hunt if it's lean.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Typically fades and dies, in about a second. When the valve clearance is inadequate, the valve heat up and get longer. Eventually, the valve doesn't close completely, and you lose compression. Typically takes 15 minutes, though.
Christopher A. Young Learn more about Jesus www.lds.org .

Hmm...that's interesting. That could cause it to just suddenly stop as though I'd turned off the fuel flow?
A can tell you that when it runs, it sounds okay other than the hunting and if I hold the throttle valve steady to prevent the hunting then it sounds very good. I could be wrong but I still believe fuel starvation.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Oren wrote: > Try loosening the gas cap 1/4 turn. If the cap is clogged a vacuum

Yeah, as I said in the original post, I suspected that but disproved it by removing the tank and setting it up a short distance away at the same height and running the engine with the gas cap completely off the tank. I was so certain that this time it would continue to run but no, it stopped the same way.
Never did see any hole in the cap so not sure how that works but it's not the cause of the stoppages.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Just a followup to say I'd adjusted the float tab so the float sits flat when upside down and I think that may have been it. More extensive tests to come but it wasn't stopping after a couple minutes. Still a little hunting. I may replace the whole carb all the same.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanks for the field report. You mighta got it.
Christopher A. Young Learn more about Jesus www.lds.org .
Just a followup to say I'd adjusted the float tab so the float sits flat when upside down and I think that may have been it. More extensive tests to come but it wasn't stopping after a couple minutes. Still a little hunting. I may replace the whole carb all the same.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Not in my world.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Does, in my world.
Hey, what's the weather like, there?
Christopher A. Young Learn more about Jesus www.lds.org .

Not in my world.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 05 Dec 2012 10:22:24 -0600, Steve Kraus

I would replace the needle and seat with a Briggs part, set the float height per Briggs and see if this doesn't improve things. Use a very new part if possible and run the genset out of fuel when stopping it to not get it pickled in ethanol.
--
Mr.E

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I always shut down by turning off the fuel flow and letting it run out.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Use ethanol free if possible. On those B&S carbs holes in the brass float are not terribly uncommon - the pivots get sloppy and the float hits the bowl and wears through. (on high hour engines.)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Given that it stops after 3 mins, I would not suspect or fiddle with the governor until the engine was running correctly. It would seem more likely the hunting could be related to the same problem that ulimately causes it to stall.

I would think with an intermittent ignition problem you'd get some backfiring. By intermittent I mean a failing coil, loose wire, etc. But the ignition could be cut off by something that cuts it off cleanly too, eg oil pressure switch? over temp? If it has those, I'd figure out how to temporarily bypass them.
it's being starved for

Carbs are the #1 source of problems in these engines. It is a bit odd though for it to run for 3 mins though, assuming it's running pretty much OK. Also, not clear if it was running OK prior to your fiddling with the float or if it ran OK at some point after that, etc. If it started with that, I'd suspect that as the problem.
My approach to these is to get a rebuild kit. Take out all the welch plugs, blow it out completely, used carb cleaner as needed. Then re-assemble, set needle valves close to where they were, or better yet per service manual and go from there.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Oh, thanks for the memory. My sister and her yuppie hubbie got a generator. It would run for a couple seconds, and quit. They bought another one, gave me the first. Only problem, a couple ounces low oil.
To the OP, please add four ounces of oil, see if that helps. Oil needs to be on the "full" level, before starting.
Christopher A. Young Learn more about Jesus www.lds.org .
I would think with an intermittent ignition problem you'd get some backfiring. By intermittent I mean a failing coil, loose wire, etc. But the ignition could be cut off by something that cuts it off cleanly too, eg oil pressure switch? over temp? If it has those, I'd figure out how to temporarily bypass them.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Thanks but this machine is not so sophisticated as to have a low oil cutoff. I changed the oil a few days ago just to be sure.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Roger that!
Well, that leaves several other options.
Christopher A. Young Learn more about Jesus www.lds.org .

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.