Home Repair forum - Briggs & Stratton Intek no power, too rich

Author

Briggs & Stratton Intek no power, too rich

furtherside@yahoo.com

2006-10-29, 5:25 pm

I have a lawnmower with a B&S 6.5HP Intek (overhead valve) engine.
It's about 4 years old, and from day one it has always started on the
first pull and ran with no issues. I had finished the lawn a couple of
weeks ago (it ran fine), and put it away. When I took it out again for
the next mowing, it was very hard to start, and it died after about 10
minutes.

The plug was all "gunked" up with carbon, unburned gas and general
crud. I *thought* I saw some bits of metal on the plug, but I can't be
sure. I cleaned it, and it ran again for about 5 minutes, and died
again.

So, here is what I did next:

1. Opened crankcase and checked governor system (it was okay).
2. Removed float bowl from carburator and cleaned everything I could
see, with carb cleaner.
3. Drained fuel tank, disposed of old fuel and bought new, fresh fuel.
4. Put in new air filter and new spark plug.

Now, the mower runs, but it still seems to be very rich. It actually
runs okay if I remove the air cleaner, but once the air cleaner is on
it loses power and starts loping, and is way too rich. It also
backfires quite a bit through the carb.

Here is what I'm wondering:

1. Could the intake valve have fractured? If it did (say, a small
piece broke off), could that make the engine run too rich? I'm
wondering this because one day the engine ran fine, and the next day it
was essentially "dead".

2. If the intake valve idea sounds silly, do you think it could just
be that the carb has a problem? I took the carb apart (the float bowl)
and cleaned everything I could, as well as I could. I'm willing to
spend the $35 on a new carb, if someone who has had some experience
with this thinks it may be worthwhile.

Thanks,
Chris

Tony Hwang

2006-10-29, 5:25 pm

furtherside@yahoo.com wrote:
> I have a lawnmower with a B&S 6.5HP Intek (overhead valve) engine.
> It's about 4 years old, and from day one it has always started on the
> first pull and ran with no issues. I had finished the lawn a couple of
> weeks ago (it ran fine), and put it away. When I took it out again for
> the next mowing, it was very hard to start, and it died after about 10
> minutes.
>
> The plug was all "gunked" up with carbon, unburned gas and general
> crud. I *thought* I saw some bits of metal on the plug, but I can't be
> sure. I cleaned it, and it ran again for about 5 minutes, and died
> again.
>
> So, here is what I did next:
>
> 1. Opened crankcase and checked governor system (it was okay).
> 2. Removed float bowl from carburator and cleaned everything I could
> see, with carb cleaner.
> 3. Drained fuel tank, disposed of old fuel and bought new, fresh fuel.
> 4. Put in new air filter and new spark plug.
>
> Now, the mower runs, but it still seems to be very rich. It actually
> runs okay if I remove the air cleaner, but once the air cleaner is on
> it loses power and starts loping, and is way too rich. It also
> backfires quite a bit through the carb.
>
> Here is what I'm wondering:
>
> 1. Could the intake valve have fractured? If it did (say, a small
> piece broke off), could that make the engine run too rich? I'm
> wondering this because one day the engine ran fine, and the next day it
> was essentially "dead".
>
> 2. If the intake valve idea sounds silly, do you think it could just
> be that the carb has a problem? I took the carb apart (the float bowl)
> and cleaned everything I could, as well as I could. I'm willing to
> spend the $35 on a new carb, if someone who has had some experience
> with this thinks it may be worthwhile.
>
> Thanks,
> Chris
>
Hmmm,
Check the gaskets? If engine vacuum is low....... Spray WD 40 generously
around gaskets if engine runs better that means air leak towards intake.

Stormin Mormon

2006-10-30, 9:25 am

More text inserted.

--

Christopher A. Young
You can't shout down a troll.
You have to starve them.
..

<furtherside@yahoo.com> wrote in message
news:1162161198.344913.103530@m7g2000cwm.googlegroups.com...
I have a lawnmower with a B&S 6.5HP Intek (overhead valve) engine.
It's about 4 years old, and from day one it has always started on the
first pull and ran with no issues. I had finished the lawn a couple
of
weeks ago (it ran fine), and put it away. When I took it out again
for
the next mowing, it was very hard to start, and it died after about 10
minutes.

The plug was all "gunked" up with carbon, unburned gas and general
crud. I *thought* I saw some bits of metal on the plug, but I can't
be
sure. I cleaned it, and it ran again for about 5 minutes, and died
again.
CY: Well, a dirty plug sure sounds like a problem. Unburned gas is a
good clue.

So, here is what I did next:

1. Opened crankcase and checked governor system (it was okay).
CY: I'd be surprised if there is a governor system in the crankcase.
But, in any case, while you have the crankcase open, you need to
change the oil and gasket. This is a LOT of work, to open the
crankcase, as you have to pull the motor off the deck, remove all the
bolts, and hope the bottom of the crankcase slides off the crankshaft.
Some larger Tecumsehs I think had a speed limiter, which was a
centrifugal thing, in the crankcase. You would have been better off to
pull the motor cover, and look at the spring assembly that controls
the throttle. Rather than open the crankcase.

2. Removed float bowl from carburator and cleaned everything I could
see, with carb cleaner.
CY: Definitely a good move.

3. Drained fuel tank, disposed of old fuel and bought new, fresh
fuel.
CY: Also good. water in the gas is a common problem.

4. Put in new air filter and new spark plug.
CY: Both good ideas.

Now, the mower runs, but it still seems to be very rich. It actually
runs okay if I remove the air cleaner, but once the air cleaner is on
it loses power and starts loping, and is way too rich. It also
backfires quite a bit through the carb.
CY: Backfiring thorugh the carb sounds like a timing problem. Makes me
wonder if you have a partial shear of the flywheel key, and the spark
is firing too soon.

Here is what I'm wondering:

1. Could the intake valve have fractured? If it did (say, a small
piece broke off), could that make the engine run too rich? I'm
wondering this because one day the engine ran fine, and the next day
it
was essentially "dead".
CY: A broken valve would make the engine run too lean. because during
the compression stroke, you'd be losing gas air mix through the valve.
Instead of keeping the mix in the cylinder.

2. If the intake valve idea sounds silly, do you think it could just
be that the carb has a problem? I took the carb apart (the float
bowl)
and cleaned everything I could, as well as I could. I'm willing to
spend the $35 on a new carb, if someone who has had some experience
with this thinks it may be worthwhile.
CY: Makes me wonder if the choke plate is opening up. I don't know the
carb you mentioned, but one with a float bowl probably has the
metering jet in the bottom. Hard to say without being there, but I'd
be thinking more of ignition timing.

Thanks,
Chris

rdglide03-dbasedos@yahoo.com

2006-10-30, 9:25 am

If you found oil on the plug, you may have broken or worn rings. Check
the compression.
Did you gently blow out the fuel inlet at the carb? Also remove the
jets and squirt carb cleaner into the holes they go in. Your gas
container and tank can build up crap that must be rinsed out with
fresh gas.
Good Luck.

Stormin Mormon wrote:
> More text inserted.
>
> --
>
> Christopher A. Young
> You can't shout down a troll.
> You have to starve them.
> .
>
> <furtherside@yahoo.com> wrote in message
> news:1162161198.344913.103530@m7g2000cwm.googlegroups.com...
> I have a lawnmower with a B&S 6.5HP Intek (overhead valve) engine.
> It's about 4 years old, and from day one it has always started on the
> first pull and ran with no issues. I had finished the lawn a couple
> of
> weeks ago (it ran fine), and put it away. When I took it out again
> for
> the next mowing, it was very hard to start, and it died after about 10
> minutes.
>
> The plug was all "gunked" up with carbon, unburned gas and general
> crud. I *thought* I saw some bits of metal on the plug, but I can't
> be
> sure. I cleaned it, and it ran again for about 5 minutes, and died
> again.
> CY: Well, a dirty plug sure sounds like a problem. Unburned gas is a
> good clue.
>
> So, here is what I did next:
>
> 1. Opened crankcase and checked governor system (it was okay).
> CY: I'd be surprised if there is a governor system in the crankcase.
> But, in any case, while you have the crankcase open, you need to
> change the oil and gasket. This is a LOT of work, to open the
> crankcase, as you have to pull the motor off the deck, remove all the
> bolts, and hope the bottom of the crankcase slides off the crankshaft.
> Some larger Tecumsehs I think had a speed limiter, which was a
> centrifugal thing, in the crankcase. You would have been better off to
> pull the motor cover, and look at the spring assembly that controls
> the throttle. Rather than open the crankcase.
>
> 2. Removed float bowl from carburator and cleaned everything I could
> see, with carb cleaner.
> CY: Definitely a good move.
>
> 3. Drained fuel tank, disposed of old fuel and bought new, fresh
> fuel.
> CY: Also good. water in the gas is a common problem.
>
> 4. Put in new air filter and new spark plug.
> CY: Both good ideas.
>
> Now, the mower runs, but it still seems to be very rich. It actually
> runs okay if I remove the air cleaner, but once the air cleaner is on
> it loses power and starts loping, and is way too rich. It also
> backfires quite a bit through the carb.
> CY: Backfiring thorugh the carb sounds like a timing problem. Makes me
> wonder if you have a partial shear of the flywheel key, and the spark
> is firing too soon.
>
> Here is what I'm wondering:
>
> 1. Could the intake valve have fractured? If it did (say, a small
> piece broke off), could that make the engine run too rich? I'm
> wondering this because one day the engine ran fine, and the next day
> it
> was essentially "dead".
> CY: A broken valve would make the engine run too lean. because during
> the compression stroke, you'd be losing gas air mix through the valve.
> Instead of keeping the mix in the cylinder.
>
> 2. If the intake valve idea sounds silly, do you think it could just
> be that the carb has a problem? I took the carb apart (the float
> bowl)
> and cleaned everything I could, as well as I could. I'm willing to
> spend the $35 on a new carb, if someone who has had some experience
> with this thinks it may be worthwhile.
> CY: Makes me wonder if the choke plate is opening up. I don't know the
> carb you mentioned, but one with a float bowl probably has the
> metering jet in the bottom. Hard to say without being there, but I'd
> be thinking more of ignition timing.
>
>
> Thanks,
> Chris

LinkBot