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6.75 Briggs and Stratton won't start after hitting something


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07-03-17, 09:58 AM   #1  
6.75 Briggs and Stratton won't start after hitting something

Hi everyone , I inherited a nice self driven lawnmower that a family member hit something g hard enough to bend a blade . After reading through some threads here , I did all the basics .
1. Cleaned carb
2. Checked for spark ( which there was )
3. Drained oil to make sure it didn't get flooded with gas
4. Popped the cover off to check timing key ( looks intact )

Even a shot of carb cleaner in the cylinder maybe gives me a puff after 10 pulls . I was hoping to find the timing key broken . I spin it over by hand with my thumb over the spark plug hole and the air pressure moves my thumb off .Here is a pic of the timing key a single well as the thing I'm pointing to is very loose . I'm not sure the purpose of this piece . It snaps into place when the magnet comes around otherwise it flops around . Looking for some more trouble shooting options , thanks . .

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07-03-17, 10:55 AM   #2  
Is the spark plug oily looking? Oil in the air filter and housing?

The piece you are pointing to should clip on the metal starter housing when you install it.


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07-03-17, 12:30 PM   #3  
Remove the flywheel the key or flywheel or crankshaft may be messed up below what you can see from the surface. Have a good one. Geo

 
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07-03-17, 03:21 PM   #4  
Spark plug and air filter look fine . I swapped the plug nto my old lawnmower as is and it fires the other mower right up . I was going to pull the flywheel but the two holes don't have threads . I figure don't I better ask you guys for advice first .

 
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07-03-17, 05:58 PM   #5  
Yeah, they aren't threaded, you have to thread them. I just run self tapping bolts into them.


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07-03-17, 07:28 PM   #6  
Sounds good , I'll pick up 2 bolts tomorrow and pop the flywheel off and report back to the forum . Any idea off hand what size of bolts to buy ?

 
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07-04-17, 02:16 AM   #7  
If I recall correctly, they are 1/4" bolts. 1/4" x 20 bolts should do the trick.


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07-06-17, 06:07 AM   #8  
Last night I pulled the flywheel . I took some pictures again . To me it seems it was lined up with proper timing . Once off , it was very easy to spin the shaft by hand . With my finger over the spark plug hole , the compression would blow my thumb off again , as well as suction it back on the next stroke . With the flywheel back on it seems to be rubbing very hard on those two pads ( one where the coil is) ( other where the red pad is) see pictures . Any other tests I can try ?

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07-06-17, 06:42 AM   #9  
Just yesterday I was talking to my Mechanic about a small Briggs engine whose Coil would respond to overheating and fail when hot . . . . behaved just fine on the bench and on a cleaner engine.

Cleaning the cooling fins of all debris can do a lot to keep these little engines running cool.

 
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07-06-17, 11:02 AM   #10  
The red pad is the engine brake. It releases when you pull the bail on the handlebar and the engine should then spin more easily. The other one is the coil armature. It should not be touching the flywheel. Loosen the bolts holding it and move it away from the flywheel and put a business card between it and the flywheel, push it together and tighten the bolts, then remove the business card. This should set the gap between them. Then see if it will run, this might have been the problem.


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07-06-17, 10:23 PM   #11  
Hey gang , first of all, I wanna say thanks for all the help so far . I'm very impressed with this forum.

Thanks Cheese for the latest reply . I'll check the coil for the correct distance to make sure it is or isn't rubbing. Would it be worth popping the valve cover off for any reason ? Some other info I forgot to add was , the last owner tried fixing it . So currently there is no air filter and the gasket behind the air filter housing is gone . Could these two bits of info contribute ?

 
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07-06-17, 10:54 PM   #12  
The gasket missing and lack of air filter won't cause the problem. Knowing the previous owner messed with it means all bets are off. I would check the valves... a rocker arm may have jumped off. It will still cause a compression/suction feeling on your thumb if a rocker arm did come off.

If all checks out, make sure the coil is not rubbing, and try again. Put a little capful of gas into the spark plug hole and see if it will respond when trying to start.

Glad you like the forum!


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07-14-17, 06:06 AM   #13  
Just a quick update . Work got crazy again , so I haven't had time to do much but check the coil . When I'm not squeezing the brake , I can slide a buisness card snugly behind one contact , and the other is rubbing . When I squeeze the engine brake , I can now get the card between both contact points . Should both of the coil contact points be set even or would starting be effected by the contacts slight different . Will hopefully be able to check the rockers this weekend .

 
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07-14-17, 09:57 AM   #14  
They should be the same. The business card should be pretty tight fit on both legs.


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07-15-17, 07:27 AM   #15  
Thanks again.... I'll re-adjust and check the valve cover . If no visible damage m I'll put it all back together and give it another try . I'll update the results .

 
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07-30-17, 03:36 PM   #16  
Sorry gang for not updating on my progress. Work gas been busy and today was my first day back in the shop .

So I adjusted the coil so each side is squished against the flywheel . Popped the valve cover off and the piston and valves all seem to be in working order as I turned the motor over by hand . Re-gapped the spark plug to .30 , poured a teaspoon of gas into the chamber , installed the plug and gave it some pills . The most I got was a double puff ( sputter) . Tried a few more times of carb cleaner squirts and just the odd sputter is all I'm getting . Can you think of anything else I could try or look at ?

 
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07-30-17, 07:00 PM   #17  
Try starting it with the kill wire unplugged from the coil. You won't be able to shut it off so have a way to pop the plug wire off without getting shocked in case it does start.


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08-04-17, 06:19 AM   #18  
I got a couple hours in the shop last night . I removed the kill switch wire . Little fuel in spark plug whole . Same thing , got a couple sputters at most . I sprayed some carb cleaner into the carb , and gave it some pulls . That way I was getting more of single small back fires . Kind of a popping . I don't want to give up .

 
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08-04-17, 10:46 AM   #19  
Check for dents in the valve cover. I've run across an engine or two that seemed perfectly fine but acted like a valve wasn't closing but when I checked the valves they were fine. I finally realized that there was a dent in the valve cover that was barely hitting the rocker arm and keeping one of the valves cracked open.


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08-06-17, 12:27 AM   #20  
What valve cover ? 6.75 and those HP engines on Briggs dont have OHV They are a L head.

Unless I am missing a post somewhere. To me it seemed in the pics that the flywheel wasn't torqued down enough and the key was in good shape.

If it was a bad bad hit I would suspect a cam timing issue. The cam jumped or the epoxy gave and the gear wheel is sliding on the shaft of the cam. I have seen it before a few times....

 
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08-06-17, 01:18 PM   #21  
The valve cover they said they removed in post #16.

"Popped the valve cover off and the piston and valves all seem to be in working order as I turned the motor over by hand ."

I think you are a little out of date on your engine knowledge:
https://www.jackssmallengines.com/ja...maam4pealw_wcb


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08-06-17, 01:45 PM   #22  
Oops Not out of date, just never thought that the thread was on a E series. I call all of the newer Ex and E sereies, E models. I never seen a model number posted or a pic of the front of the engine so I assumed it was a L head type engine.

How you been Cheese ??

 
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08-09-17, 06:42 AM   #23  
Maybe I used the wrong terms for valve cover ....what I pulled was the cover where the spark plug screws in to see the top of the piston and two valves . I also inscpected the cover where you could see the valve springs . Thinking of a car , a valve cover you can see the rockers and push rods . ( no idea where that would be on this engine )

So, I did notice one of the valve springs was a little crooked , moved it back into place and carried on .

Here's what I am noticing . When the mower sits all week , and the fuel chamber etc is all dried out , I can give it a tiny shot of gas, or carb clean . It actually fired for a couple seconds . When I give it another shot , like half a water bottle cap of gas, I barely get a sign of firing . Every time I pull the spark plug and it's noticeable wet with fuel. This is either putting fuel into the carb or direct in the spark plug whole .

 
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08-10-17, 01:04 AM   #24  
Sounds like you pulled the head then, and this is a flat head engine.
If the plug is always wet, it wounds like it's flooded. See any gas dripping from the carb? Is the air filter wet?

Doing good Boudreaux, thanks.


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08-10-17, 08:09 AM   #25  
I drained the tank about a month ago and it's bone dry . I mean, even a little bit of gas or car cleaner shot , it may fire once at the beginning , then after the next little shot , it doesn't fire and the plug gets wet . I should video the spark plug sparking . Perhaps it's not enough spark ?

 
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08-10-17, 11:01 AM   #26  
Ok, what happens if you put some gas in the tank and see what it will do after fixing the previous stuff?


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08-10-17, 09:21 PM   #27  
I filled the Jerry can tonight and I'll give it a go this weekend . Fingers crossed

 
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08-12-17, 11:35 PM   #28  
Sorry I have not been on in a while, I just saw that I was not even on here. Did you ever get the mower to start or even POP ??

 
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