Briggs& Stratton engine will not turn over

JimP2014

Well-Known Member
Joined
Jun 13, 2014
Threads
5
Messages
292
Stop spraying carb cleaner into it. It doesn't burn well. Try spraying starting fluid. I doubt that it has a kill switch. There is probably an ignition switch somewhere on it. It probably is the switch you're turning to crank it over. To test the compression, remove the sparkplug, stick a finger or thumb over the sparkplug hole and crank the engine over. If it has compression, it will push your finger/thumb away from the hole.
Hello I bought a compression testing kit and although one of the fittings did not fit perfectly with a spark plug hole, there is an adapter that makes a pretty good fit and the compression was 86 psi.

I stopped using the carburetor cleaner. The only reason I mainly did that is so I wouldn't have to keep recharging the battery every couple hours but now it starts right up. After that it goes into the hunting and surging.

Jim
 
Joined
Jun 30, 2020
Threads
3
Messages
39
I think you're barking up the wrong tree. If the engine was cranking and just popping and backfiring when you sprayed carb cleaner into the air intake, that sounds like a valve problem. You might have a bent push rod or valve lashing way out of wack. Take the rocker cover(s) off and see what's happening in there.
 

JimP2014

Well-Known Member
Joined
Jun 13, 2014
Threads
5
Messages
292
I think you're barking up the wrong tree. If the engine was cranking and just popping and backfiring when you sprayed carb cleaner into the air intake, that sounds like a valve problem. You might have a bent push rod or valve lashing way out of wack. Take the rocker cover(s) off and see what's happening in there.
I absolutely can do this tomorrow just to at least make sure the valve clearances are correct. The push rods are not bent. The post that the rocker arms sit on are solid against the plate and anything else that I find that might be unusual, but that's a good suggestion.

Jim
 

WeldGuy

Forum Newbie
Joined
Jun 5, 2012
Threads
3
Messages
8
BTW... "Won't turn over" means there's no rotation.
"Won't start" seems a better description of your problem.
 

Fish

Lawn Pro
Joined
Aug 2, 2013
Threads
11
Messages
5,143
One think to look at, with the valve cover off, rotate the engine by hand and watch the movement of the rocker arms. Make sure that they travel the same distance up and down.
 

DABS

Member
Joined
Feb 1, 2015
Threads
3
Messages
21
Jim, replacing the fan with another one may end up with the same result. Engine working at full rev may have lost the governor gear and overreving the engine which can bend the crankshaft, break fins off the fan, shear the key, and damage the windings under the flywheel leaving copper shavings, overheat the engine and maybe bent the pushrod. You may be chasing results rather than finding the cause?
 

dwzkd

Member
Joined
Oct 20, 2020
Threads
0
Messages
27
Did you ever get the engine model and date code? It should be stamped into the valve cover. If hard to read, get some "grime" on your finger and rub it across it. The grime will fill in the letters and give you contrast. Also can take a photo of it, if hard to read.

There are several parts (fan included) that require the date code to get the correct fan.

Since your exhaust is getting superhot, it seems you are running lean... Popping and sputtering could be an ignition issue on top of this. One thing I have seen is the ignition switch (or connections) going bad and intermittently killing the coil.

Spark related, I would pull the plug and short the metal base of the plug to the engine, then crank it. If you get spark your ignition system works to provide spark. Since it starts, this is probably ok. To rule out other issues "killing" spark intermittently, pull the kill wire from the coil (you will have to remove the air cover). Start it and see if it runs ok. If so, then something is killing the coil (ign switch, safety switches etc.). NOTE: I have seen spark look "ok" with a spark checker and have this issue. You could kind of see the spark "stutter" but it was still sparking. You can kill the engine by pulling the plug wire (using insulated pliers) or short the coil kill terminal to the frame of the coil with a screwdriver. If the engine continues to run rough with the kill wire removed, then the only spark related issue can be timing related.

Timing related spark issues would be (1) sheared flywheel key; (2) Coil upside down; (3) coil gap to magnet on flywheel; (4) wrong or bad parts (coil, flywheel, plug, plug wire); (5) if your insulation on the plug wire is weak, cracked or chewed by mice, the spark signal can be messed up as it will jump the air gap to the engine block (this will cause missing);

I suggest, going through systematically to verify each (spark, fuel, air, compression, valve lash; etc.) one system at a time.

As for running lean; Check air flow; make sure you don't have any air drawing in the system between carburetor and engine; (i.e. check the gasket between the carburetor and the engine; make sure the bolts are tight). You can also spray carb cleaner; or similar at the gasket point while the engine is running (make sure it doesn't enter the front of the carburetor though)... If it starts to run smoothly when you squirt it with carb cleaner (and it is not going into the front of the carb), then you have an air leak between the carb and engine. Also check the throttle and choke shafts where they enter the carburetor. If these are worn, you can get air leaking in there. Also check to make sure your throttle/choke plates are securely attached to the shafts (by looking into the input side of the carburetor)

Another test for running lean, is to move the choke to slowly towards the closed position and see if it starts to run smoothly.

Others may be able to chime in similar tests, but I would suggest going through systematically and prove out each system.
 
Last edited:

JimP2014

Well-Known Member
Joined
Jun 13, 2014
Threads
5
Messages
292
One think to look at, with the valve cover off, rotate the engine by hand and watch the movement of the rocker arms. Make sure that they travel the same distance up and down.
I actually did this maybe 5 days ago and I came up with a distance of travel of 1 cm approximately for each valve and another member of this forum computed the same thing for his machine. If the 1 cm difference seems wrong then I have the units right here in my description wrong. But whatever I did for the test, the other person in this form did the same test and came up with the same results is what I'm trying to say.
 

JimP2014

Well-Known Member
Joined
Jun 13, 2014
Threads
5
Messages
292
BTW... "Won't turn over" means there's no rotation.
"Won't start" seems a better description of your problem.
I see what you're saying and that was definitely a mistake on my part as far as describing the problem. But the fact is the flywheel was rotating and nothing else was happening. And at the time the reason why that was true is because of flywheel key was sheered and that was fixed and as of July 6th around 5:00 p.m. starts up perfectly and then it hunts and surges.

Jim
 

JimP2014

Well-Known Member
Joined
Jun 13, 2014
Threads
5
Messages
292
Did you ever get the engine model and date code? It should be stamped into the valve cover. If hard to read, get some "grime" on your finger and rub it across it. The grime will fill in the letters and give you contrast. Also can take a photo of it, if hard to read.

There are several parts (fan included) that require the date code to get the correct fan.

Jim, replacing the fan with another one may end up with the same result. Engine working at full rev may have lost the governor gear and overreving the engine which can bend the crankshaft, break fins off the fan, shear the key, and damage the windings under the flywheel leaving copper shavings, overheat the engine and maybe bent the pushrod. You may be chasing results rather than finding the cause?
I actually was thinking this just about the fan that even if I get all the fins I'm still going to end up with around 700° f. But like you're saying regarding the governor, since the component is inside and I'm not an engine expert wouldn't I would not know this if this is broken or not. If something is broken on the outside of the engine I could clearly see that. But I will look at this tomorrow and see if all the symptoms that the sentient exhibited add up to a governor issue. Although I can say I did try and adjust it maybe 10 days ago and it seemed like I said it correctly or I should say it was set correctly and I didn't do anything more than loosen up a nut and then tighten it back up
 
Top