Any one good with lawn mower engines?

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J Miller
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Any one good with lawn mower engines?

Post by J Miller »

We have acquired a Craftsman lawnmower with a Briggs & Straten engine.
I started it right off even though the gas tank was empty. Later we filled it up and mowed the yard. The gas tank had a crack in it so before using it again we put on a new tank and replaced the clogged air filter. Oh we also put in a new spark plug.
Fresh gas, yank yank yank on the cord and ..... nothing. Not a pop.
I checked the new plug and; no spark. Checked the old plug and spark, spark, spark. Put the old plug back in.
Still no start.

At this point I'm pretty sure it's not getting fuel. But I did nothing to the carb other than hose off the crud externally.
All I did was change out the gas tank.

Before I tear this thing apart again, does anyone have any ideas?

Joe
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Pitchy
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Re: Any one good with lawn mower engines?

Post by Pitchy »

Well Joe it makes no sense the new plug doesn`t spark, sometimes it`s hard to see the spark on the clean new plug.
If it`s not getting gas of coarse it won`t fire, does it have a choke or a primmer bulb?
If a primmer bulb they can crack and not squirt gas in, if it has a choke make sure it`s closing.
Take the air cleaner off and put a little gas down the carb and try it, using caution of coarse .
If it runs then the carb is plugged up or the choke isn`t working, also try starting it with the throttle just open.
If it`s a flooded condition disregard all of the above and find out why it`s flooding.
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Re: Any one good with lawn mower engines?

Post by J Miller »

Pitchy,

I'll check those things out. the weird thing is that the old air cleaner was soaked in oil, and totally clogged with dirt and grass. But somehow it was running. Now with a clean air filter it wont run. :?:

It does have a priming bulb, but I never used it until yesterday, it would on the third pull every time. Tried to start it again today and it still won't start.

There is no manual throttle cable on this mower and no manual choke. The throttle is controlled by a flapper valve somewhere under the top cover. The lever connected to the springs has three positions, we tried them all. No go.
I never changed any of the settings on that either.

I have theory that I'll check later today, I'll report back on way or the other.

Joe
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Pitchy
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Re: Any one good with lawn mower engines?

Post by Pitchy »

Sounds to me like the carb is partially plugged up and why it would run with the clogged air cleaner, it would act like a choke.
I`d still put a little gas in the carb and see if it fires, if it starts it ain`t getting gas somehow.
Just be careful Joe.
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Chuck 100 yd
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Re: Any one good with lawn mower engines?

Post by Chuck 100 yd »

I wrenched on lawn equipment for the last 14 years of my working days. There are many variations of B&S lawn mower engines.
I wish I could be able to check it out for you as I could troubleshoot the problem shortly as I have done thousands over the years.
Like Pitchy said,if you have compression,fuel (gas,not diesel) and spark, she should run. Remove He air filter and squirt some gas in the intake and try to start it. If it fires you have a fuel issue. Remove the fuel line from the carb and make sure fuel even comes out of the new tank. If it don't fire on a prime,check your ignition again. If you removed the air filter base, the gasket behind it is critical to the operation of the primer. Check that close,no prime,no start.Good luck!
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Re: Any one good with lawn mower engines?

Post by J Miller »

I checked fuel flow from the tank, OK

Took off the air cleaner and watched the primer jet, it squirts.

I primed the engine and by playing with the throttle thing I got it running. But it will only run with the throttle thingy in the center position, and while running it surges. You can hear the engine firing, then it coasts, then it fires some more.
The exhaust sound is a sharp popping noise, not a normal B&S sound.

So, it's a fuel problem. Yuck! I'm no good with mower carbs. I wonder if I put carb cleaner in the tank and run it if that might clean it out?

Joe
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Re: Any one good with lawn mower engines?

Post by Pitchy »

Sounds like the carb is clogged up Joe, take it off and either take it apart and clean or take it too a shop and have it rebuilt.
Sea foam or similar may work but it will have to run long enough to do any good.
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Re: Any one good with lawn mower engines?

Post by GunnyMack »

I'd add that you might want to change the fuel line to one that is good with ethanol blended gas, the alcohol eats the inside of the lines, causing issues like you are seeing. The line gets sucked shut not allowing gas to flow. Granted this probably has 3/8 line but this could be the reason it is surging. Just my 2 cents, had similar issue with one of my outboards. New lines and fixed the problem.
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Re: Any one good with lawn mower engines?

Post by J Miller »

Pitchy,

Have some Berryman, so will try that for now. It doesn't seem to be running any worse than the last time we mowed the yard, so we'll see what happens.

GunnyMack,

Not a bad idea. I'll do that.

Joe
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Re: Any one good with lawn mower engines?

Post by Chuck 100 yd »

An engine surges because the rpm is not up to what the governors adjustment/spring is set to. The governor opens the throttle plate and then the engine races above the governors setting. Repeat,repeat,repeat (surge). That means the carburetor is just clogged up or dirty. Remove and clean it. Those carburetors are the simplest thing to work on. If you can tear down a Win. 94 ,
you can fix a B&S carburetor in your sleep.
Under the engine cover,on most B&S small engines, you will find a wind vane governor and spring with a linkage that connects to the carburetors throttle shaft. Wind from a fan mounted on the flywheel operates the wind vane and inturn operates the throttle shaft. Insure that all these parts are ok and not broken or missing. Clean the carb,replace any rubber parts and gaskets found in the carb even if they look good. Or remove and dissasemble and clean the carb and have your local shop reassemble if you have to. Go mow the lawn! :D
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Re: Any one good with lawn mower engines?

Post by J Miller »

Well, went out and got it started. Started mowing the yard and it calmed down and started running a bit better. Wifie came out and took over and I poured some Berryman into the tank. Not long after that it quieted down even more.

No doubt the carb needs rebuilt, but not today. Tomorrow I'll put a new fuel hose on it just cos. Then I'll keep pouring the Berryman into till that can is gone.

But for now the yard is mowed and the stinking city of FT Wayne can't fine us.

Joe
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Re: Any one good with lawn mower engines?

Post by Pitchy »

Good on you Joe, now send the city a bill for the work ya did. :wink:
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Re: Any one good with lawn mower engines?

Post by J Miller »

Pitchy wrote: Wed Apr 26, 2017 5:11 pm Good on you Joe, now send the city a bill for the work ya did. :wink:
I wish I could. Ah but the way it works is the government takes, they never pay. Billing them would be useless.

Joe
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Re: Any one good with lawn mower engines?

Post by Pitchy »

J Miller wrote: Thu Apr 27, 2017 7:04 am
Pitchy wrote: Wed Apr 26, 2017 5:11 pm Good on you Joe, now send the city a bill for the work ya did. :wink:
I wish I could. Ah but the way it works is the government takes, they never pay. Billing them would be useless.

Joe
I know was just joshing ya, only seems fair that if they can fine ya for not mowing they should help maintain the equipment.
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Re: Any one good with lawn mower engines?

Post by Blaine »

Ft Wayne is ChicagoSouth....very corrupt. :evil:
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Re: Any one good with lawn mower engines?

Post by J Miller »

BlaineG wrote: Thu Apr 27, 2017 12:40 pm Ft Wayne is ChicagoSouth....very corrupt. :evil:
You ain't just whistling Dixie!

Joe
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Re: Any one good with lawn mower engines?

Post by J Miller »

Chuck 100 yd you have email.


Finally got the new fuel hose on the mower, then squirted some carb cleaner directly into the float bowl. Got it started and mowed the yard.
The carb sure does need attention, but I'm not likin the idea. I can rebuild Quadrajets, AFB's and most any normal automotive carb, but these little lawnmower carbs just confound me. :roll:

Joe
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Chuck 100 yd
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Re: Any one good with lawn mower engines?

Post by Chuck 100 yd »

Joe , I don't see any new mail . What can I do to help? If you can take a quadrajet apart and get it back together that little Briggs carb is less than nothing in comparison. Just replace the needle and its little seat and the float bowl 'O' ring and main jet gasket.
Screw a drywall screw into the rubber inlet needle's seat and pull it out. Note how it was installed, it has an up and a down side. Basically, the needle goes against the side of the seat that has the rounded hole.
Replace the air filter base gasket, there are different types of that gasket, make sure to match it up with the old one. If it is not right it will not prime.
Make sure the main jet is clear and put it all back together.
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Re: Any one good with lawn mower engines?

Post by J Miller »

Chuck,
I sent the email through the forum system. Here's what I sent:
Chuck,

Just mowed the yard the 3rd time. This time it gave us moderate trouble
starting, but once started it kept going till we were through.

You are correct, the carb is mucked up. I replaced the fuel hose and
squirted some carb cleaner directly into the float bowl. After the third
try it didn't die so we headed out to the yard and mowed it. While we
were running it I poured a little more carb cleaner into the gas tank.
Probably isn't gonna help much, but maybe?

So it's gonna need a carb overhaul, can you give me some tips on doing
that? I've never had any luck with small engine carbs. Don't know why, I
can rebuild a Quadrajet or an AFB or any of the big FoMoCo carbs, but a
lowly B&S carb just confounds me.

Here is the B&S engine info: Model Type: 12H802-2639-B1 Code: 00110357

The Craftsman info is: Model: 917-388720 Serial # 120500M 017954
and here is sears page that gives all the exploded drawings:
http://www.searspartsdirect.com/model-n ... 917.388720

While I was looking for that info I found out why the exhaust was so noisy
... no muffler. :lol:

Joe
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Re: Any one good with lawn mower engines?

Post by Chuck 100 yd »

Joe, it don't take much to gunk up the main jet, it's tiny. It's in the brass plug that screws into the bottom and holds the float bowl on. Remove it and rod it out with a tiny wire,I use a welding torch tip cleaner. A paper clip is way too big. Something like a small sewing needle will work, or guitar string ? Good luck. Sometimes those carburetors get so corroded they just have to be replaced.

At one time,30 years ago, Briggs had a recall on those fuel tanks. The seams would open up and leak all over the mower.big fire hazard. I did dozens of them every summer for several years.

Don't order mower parts from Sears. You have to call in your order and look up your own parts online. You give them your credit card number and wait. They ship your order from several different warehouses with a shipping charge on each one. Then when they come they may not be the right parts. I refuse to work on Sears stuff for that reason.You could buy a new mower cheaper than the parts could cost to repair a carb from Sears. Find a local shop and deal with them.
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Re: Any one good with lawn mower engines?

Post by harry »

Joe I use these guys for my small engine B&S parts
https://www.jackssmallengines.com/jacks ... 02-2639-b1
Just open the PDF file in the parts manual section and it will give you all the part numbers

Just the carb: https://www.jackssmallengines.com/jacks ... carburetor
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Re: Any one good with lawn mower engines?

Post by 41 Redhawk »

Joe,

You mentioned you replaced the air filter because the old was gunked up and oily. Assuming it is a foam filter it does need to have some oil in it. That is what traps the fine dirt. It also cuts the air flow a bit which richens the mixture a tad. Be sure you oil the new one with some motor oil. I generally oil it up and then squeeze out all the excess.
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Re: Any one good with lawn mower engines?

Post by Chuck 100 yd »

According to the Briggs latest service schools recomendations, any foam element that is used along with a pleated paper cartridge needs to NOT be oiled but left dry. The very early engines that had only a foam air filter should be very lightly oiled. A few drops of engine oil needed into the foam to distribute it and then squeezed in a rag to remove most of it back out, is suggested.
Often the air filters get fouled with engine oil because people tip the mower over the wrong way and engine oil comes from the crankcase to the air filter via the crankcase vent tube. Allways tip the mower over with the carburetor side up to prevent this.
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Re: Any one good with lawn mower engines?

Post by J Miller »

41 Redhawk, Chuck 100 yd,

This mower uses a pleated paper air filter just like a car. I guess that's the new thing cos it's the first lawnmower I've ever had that didn't have a foam filter.


I'd better check the filter then. I tipped it over to the air filter side when I drained the gas tank to replace the fuel hose.

Joe
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