# Briggs Intek Misfiring - Need help!



## JawjaBoy

I'm afraid I'm not the most knowledgeable small engine mechanic around and I've run into a problem with my garden tractor that I can't solve.

Recently, the engine has started misfiring and popping from idle up through full throttle. It is a Briggs & Stratton Intek 20hp Twin. 

I have checked the wiring and so far have found no shorts or breaks. In the process of troubleshooting, I decided to pull the plug wires while the engine was running and see what happened. When I pull the right hand wire (when viewed from above) the engine quits misfiring and continues to run. When I pull the left hand wire, the engine quits immediately. Could the magneto on the right cylinder be bad? Could there be other possible culprits??

Any suggestions would be appreciated as I use my tractor/mower almost daily this time of year!


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## agmantoo

Check the valve setting on the side that is misfiring.


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## Travis in Louisiana

I got an 18 hp Briggs, OHV. It is 8 years old. It is starting to burn a lot of oil. I waas mowing with it and it started misfiring and popping. It has only one plug. I took it out and it was covered in baked on oil. I cleaned the tip and put it back on. It ran good. This may not help your problem, but it seems one of your plugs is not firing, be it a dirty plug, bad coil, or other.


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## JawjaBoy

agmantoo said:


> Check the valve setting on the side that is misfiring.


In the searches I've done online this has come up several times so I'm going to check it out today. I do know that the valve lash has never been checked on this engine and I've had it since it was new, 2003. It would have been checked long ago if I had been aware that it was regular maintenance point on this engine!:doh:



Travis in Louisiana said:


> I got an 18 hp Briggs, OHV. It is 8 years old. It is starting to burn a lot of oil. I was mowing with it and it started misfiring and popping. It has only one plug. I took it out and it was covered in baked on oil. I cleaned the tip and put it back on. It ran good. This may not help your problem, but it seems one of your plugs is not firing, be it a dirty plug, bad coil, or other.


The plugs looked pretty good, but they are going to get replaced today along with the fuel filter, fuel lines, air filter, oil filter and some fresh Rotella.

If one of these doesn't cure it, I'm going to acquire a tester and make sure the coils are good. The engine has been spot on up until this so I'm hoping its just something minor that will be easy to fix.


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## lonelytree

Check the shear key on the crank.


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## Tim_H

I went through that with my briggs intek last year, I took the carburetor off and cleaned the jets out. Problem solved. Since then I've been mixing about a cup of Marvel Mystery Oil per 5 gallons of gas and haven't had a trouble since. --Tim


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## JawjaBoy

lonelytree said:


> Check the shear key on the crank.


Shear key appears OK.

Adjusted valve lash as it was .009 on one and .011 on all others. Installed new plugs, fuel line and filter, oil and oil filter, air filter and pre-filter. I'll have to say that it starts quicker than it has in a loooong time!

Buuuutttt.......it still pops and misses.:grit:



Tim_H said:


> I went through that with my briggs intek last year, I took the carburetor off and cleaned the jets out. Problem solved. Since then I've been mixing about a cup of Marvel Mystery Oil per 5 gallons of gas and haven't had a trouble since. --Tim


Looks like I will have to try this. How hard was it to do? Any advice before I start taking things apart?


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## agmantoo

JawjaBoy
What reading did you adjust the valves. I understand the exhaust valve setting is critical.


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## JawjaBoy

agmantoo said:


> JawjaBoy
> What reading did you adjust the valves. I understand the exhaust valve setting is critical.


I adjusted all of them to .004".


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## plowjockey

If you did the "plug wire" test and removing one, made no difference and removing the other, killed the engine immediately, I'm not sure why focusing on the valves, would be of any real immediate benefit.

Even if a valve was off, the ignition should still fire and the cylinder attempt to do something.

How about a $15 ignition tester?

http://www.northerntool.com/shop/tools/product_200581094_200581094?cm_mmc=Google-pla-_-Auto%20Repair-_-Automotive%20Diagnostics-_-29009&ci_src=17588969&ci_sku=29009&gclid=CM2--ovq5rYCFaxaMgodYicAVA

good luck


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## agmantoo

My understanding is that the engine does run but there is a problem in that it still pops. These engines are noted for valve issues. I have never set the valves as some say on the internet but I have read that a number of persons either set the exhaust valve to .001 or less and others put the piston to within 15 degrees before TDC and then turn the adjusting nut another 1/4 turn. I have only had one of these engines and I do not want another.


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## plowjockey

I can't find my copy, but somewhere in cyberspace, there is a free downloadable B&S manual, to show how to set the valves/timing, and other settings, on the Intek engines.

I'll see if I can find the link again.


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## agmantoo

Plowjockey

I know that YouTube did have some videos on setting the valve clearance.


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## JawjaBoy

Will be checking into an ignition tester, but I'm planning to clean the carb as well. The thing has been going for 10 years now, often is some rough conditions, so it probably needs it anyway. 

As for the valves, I'm not sure how much it helped, if any, with the popping and missing, but it sure helped with starting. The engine hasn't started as easily as it does now in many years.


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## Bearfootfarm

> When I pull the right hand wire (when viewed from above) the engine quits misfiring


Maybe the plug wire is bad and firing intermittently


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## agmantoo

JawjaBoy
Just temporarily snug up the exhaust valve on the right hand cylinder and see what happens. Better yet read this
http://pkjones.hubpages.com/hub/Hard-to-start-Briggs-and-Stratton-engine


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## Tim_H

JawjaBoy said:


> Shear key appears OK.
> 
> Adjusted valve lash as it was .009 on one and .011 on all others. Installed new plugs, fuel line and filter, oil and oil filter, air filter and pre-filter. I'll have to say that it starts quicker than it has in a loooong time!
> 
> Buuuutttt.......it still pops and misses.:grit:
> 
> 
> 
> Looks like I will have to try this. How hard was it to do? Any advice before I start taking things apart?



It's not too difficult just take good notes as to how parts are assembled.


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## wannabechef

I'm going to guess it the coil and if I recall its a single coil.


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## JawjaBoy

Tim_H said:


> It's not too difficult just take good notes as to how parts are assembled.


Maybe I can handle it. I do take fishing reels apart for cleaning and have always been able to get them back together so maybe the carb won't be too bad.



wannabechef said:


> I'm going to guess it the coil and if I recall its a single coil.


There is a coil for each cylinder. If I can make sure one is bad I will pick up a new one from Agri Supply. They are about $27 and it probably wouldn't hurt to put new ones on anyway.


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## agmantoo

Switch the coils and see if the other bank runs OK when tested as before by removing the other plug wire


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## JawjaBoy

agmantoo said:


> Switch the coils and see if the other bank runs OK when tested as before by removing the other plug wire


I really should have thought of this myself! One way or another, I gotta get this thing running right because the grass is getting outta hand. We're starting to lost track of the Dachshunds!!


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## agmantoo

I hope that the issue is with the coil. However, I recall all the problems I had attempting to get the valves set. Did you read about the special design of the lobe on the cam for the exhaust valve. In my situation I was unaware of this engineering feat and I kept trying to adjust the valves in the manner that valves were set for decades. Please continue to keep us informed.


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## JawjaBoy

It'll be monday before I get a chance to work on it again as I have to work tonight and tomorrow night. I will let you know the outcome.


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## JawjaBoy

Came in this morning from work and decided to put my leg up and let it relax a bit (see Beware Rotten Flooring thread) before getting into working on the mower. I didn't mean to fall asleep in the recliner. Honest!

Finally got out and switched coil packs around and there is no difference. Still runs fine when right plug wire is removed and dies when left wire is removed. Whats worrying me most is that it sounds _normal_ when only running on the left cylinder! The right cylinder IS firing as I got a big blue spark every time I got the plug wire anywhere close to the plug.

All I can figure is that the right cylinder is either not getting fuel or not getting enough fuel. I guess my next step is to pull the carb and see if a good cleaning gets me running right again.


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## agmantoo

Can you do a compression test on the cylinder that has the miss? IMO it is not the carb since only 1 cylinder is having issues.
Have you switched the plugs and the plug wire?


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## JawjaBoy

agmantoo said:


> Can you do a compression test on the cylinder that has the miss? IMO it is not the carb since only 1 cylinder is having issues.
> Have you switched the plugs and the plug wire?


Will have to either buy or borrow a compression tester as I don't currently have one. Plugs are brand new and plug wires are made as part of the coils. 

Went ahead and decided to pull the carb apart and clean everything. Will reassemble tomorrow and try it out. 

This thing is starting to get under my skin!


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## lonelytree

Check valves. Burnt or maladjusted.


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## JawjaBoy

Finally got all the parts I needed and got the carb stripped, cleaned and reassembled. Got the carb back on the engine and dribbled a little gas into the intake. She fired right up! 

Now I have run into another problem. The engine is running smoothly now, but it won't drop RPMs down to idle speed. It fires up at what sounds like half throttle and will throttle up to full, but not down to idle speed.

Now I gotta get this figured out. I did use the mower to cut the grass today and it worked fine, but I want this thing to work like it should. Oh well, I'm like Grandad, give me some time and I will figure anything out!


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