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11hp Briggs Stratton L-head engine will not start

11hp briggs stratton l-head

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16 replies to this topic

#1 Olav OFFLINE  

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Posted May 27, 2016 - 05:40 AM

Hi!

 

This is my first post  here. I have a Stiga lawn mower with 11HP 400cc Briggs Stratton. This will not start, I don't know what the story is before i got into my workshop. I have done a basic examination and done following:

 

1- Spark plug *2

2- Inspected if there is spark. - OK but not strong blue, should be enough.

3- Cleaned carburator and tank. Tried starting with "Stargas"/ ether.

4- Inspected the key on flywheel OK

5- Clearance between Coilpack and flywheel OK

6- Valve clearance - OK

7- Compression test, was not high but not so low it would be an issue. Anyway i pulled the head laped the valves and assemled

8- Rechecked valves- OK

9- Resistanse check of coil with HT lead. Found this to be 10Kohm that apparently it should be in the 5kohm range.Got a better spark but had spark before this also.

 

Anyone having any ideas ?

 

Regards

 

Olav

 



#2 boyscout862 OFFLINE  

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Posted May 27, 2016 - 06:32 AM

Welcome to GTT.  It sounds like you have gone through the normal troubleshooting steps but I don't understand a few things. Does it run with starting fluid?  Did you check and adjust the valve lash? When you did the compression check, were you turning it backwards so that the compression release doesn't give you a false low reading? Is gasoline getting to the carb? I've seen filters and lines plug often. Check our Manuals Section for the engine manual. It will have a good section on Troubleshooting.

 

We are happy to help, when you've got questions.  Sometimes pics will help clarify so, add them when you can. Good Luck, Rick



#3 crittersf1 OFFLINE  

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Posted May 27, 2016 - 07:40 AM

:welcometogttalk: :camera:



#4 Olav OFFLINE  

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Posted May 27, 2016 - 07:45 AM

Thank you for your reply,

 

- Don't run on starting fluid.

- Did not adjust the lash as it was OK within spec.

- I was doing the compression test with starter and also leak down test. All seems to be OK

- Cleaned tank and carb. Fresh fuel, filter and hoses.

 

I don't think this engine has decompression function.   I have been working with engines since  -87 all, from  50cc  2Hp scooters to marine engines on 10 000 hp so this has turned into "issue of proud". This is killing me :-(

 

 

I will look for the manual.

 

Olav


Edited by Olav, May 27, 2016 - 07:46 AM.


#5 Bruce Dorsi OFFLINE  

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Posted May 27, 2016 - 08:05 AM

Welcome to GTT, Olav !

 

It sounds like you know your way around engines!

 

You have the basics covered.

 

Today's thinking is that the spark does not have to be blue, as long as it will jump a 3/16"-1/4" gap.

 

On a B&S engine, the flywheel key does not have to be sheared to throw the ignition timing off.  .....If the flywheel key has any marks on its sides, it should be replaced.

 

While cranking, do you feel a strong suction at the carb inlet?  ....After cranking, is the spark plug wet or dry?  ....If it is wet, the plug is probably fouled and will need to be dried by compressed air or by burning the residue with a flame.  ...Is the fuel fresh and combustible?



#6 Olav OFFLINE  

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Posted May 27, 2016 - 08:42 AM

Fresh fuel, I might have to take a look at the key on crank and camshaft . I tried 2 sparkplugs dry so that is not the problem. But it should atleast fire a little on starting fluid or backfire ...,

#7 lrhredjb OFFLINE  

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Posted May 27, 2016 - 10:13 AM

Hallo Olav and welcome. Do you have an in line spark checker that would allow you to see if you are getting spark with the plug installed and cranking? Sometimes plugs won't fire under compression. Also make sure the battery is well charged. Possibly the timing is way off somehow and the spark is coming at the wrong time. Good luck!



#8 Bolens 1000 OFFLINE  

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Posted May 27, 2016 - 11:08 AM

As mentioned a spark outside the cylinder may mean nothing if the spark is weak, I would suggest getting an inline spark tester



#9 EricFromPa ONLINE  

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Posted May 27, 2016 - 04:02 PM

Did you try putting a fresh spark plug in it? If it doesn't have enough spark to fire with starter fluid then you need a new coil.

 

Watch you don't blow yourself up using that stuff.I burnt 1/2 the hair off my head off Once.I'll never use starting fluid on another small engine that's for certain.1 small cough through the carb because of a partly sheared flywheel key is all it takes.



#10 speedbird OFFLINE  

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Posted May 27, 2016 - 06:39 PM

I've had a couple of Briggs engines that looked as if they had reasonable spark but wouldn't run and it turned out to be the coil. The service book that I have for B&S engines say's that It  usually isn't the coil but I find it often is the coil. Also I agree if it wont fire on Quikstart you have a spark problem.



#11 Olav OFFLINE  

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Posted May 28, 2016 - 12:58 AM

I will look into this again this weekend. This is really bugging me. I will also run a leak down test again.

#12 Olav OFFLINE  

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Posted May 29, 2016 - 05:34 AM

I obvously missed something. I ran a new leakdown test. I found s major leak thru piston/ sylinder. I pulled the piston and found no damage or wear. I guess the sylinder is glazed and needs to be honed. The rings are OK and end clearance looks good. I have to check what spares are avilable and cost. The coil cost 120 $ here in Norway...

#13 KennyP ONLINE  

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Posted May 29, 2016 - 06:22 AM

Check the valves also. They can leak some and cause issues.



#14 Olav OFFLINE  

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Posted May 29, 2016 - 06:33 AM

Lapped sealing OK. They was leaking before i lapped them.
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#15 Olav OFFLINE  

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Posted May 29, 2016 - 11:09 AM

Lapped sealing OK. They was leaking before i lapped them.




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