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Riddle for you

#1

jonvh

jonvh

I've got a riddle for you:
"What has an engine that attempts to start, has a spark at the plugs, clean carburetor and air filter, gas in the tank, yet will not start up?"

Answer:
My lawnmower!

Ignition coil is good and I'm getting a spark. Fuel filter is clean and fuel is getting to the carburetor. I haven't pulled it apart to confirm, but when I spin the flywheel by hand, I can hear the valves opening and closing. I'm not sure that brand matters, but it's a Briggs & Stratton. Battery has good charge. Any idea of where I should start looking?

Thanks in advance, please let me know if additional information is needed.
-Jonathan


#2

B

bertsmobile1

Cute
Brand and model numbers DO MATTER as does the type of MOWER.
Your problems fit a broken fuel solenoid perfectly but if it is a push mower then you won't have one.

SO very general
Tip a small amout of fuel down the plug hole & try to start.
Engine fires = ignition timing is good
Do the same at the carburettor & engine fires then valve timing is good and you have a fuel supply problem or choke problem.


#3

T

Tinkerer200

Battery has good charge? Then maybe ridding mower? IF so,check the flywheel key and next time when asking an engine question, post the engine make and model number, makes a difference.

Walt Conner


#4

R

Rivets

If you can hear the valves opening and closing, you’ve got great hearing, plus something is not right in the valve train. You should not be able to hear valve movement.


#5

jonvh

jonvh

bertsmobile1 said:
Cute
Brand and model numbers DO MATTER as does the type of MOWER.
Your problems fit a broken fuel solenoid perfectly but if it is a push mower then you won't have one.

SO very general
Tip a small amout of fuel down the plug hole & try to start.
Engine fires = ignition timing is good
Do the same at the carburettor & engine fires then valve timing is good and you have a fuel supply problem or choke problem.
Click to expand...
This is on a Briggs & Stratton 42E707, circa 1994. I don't see a fuel solenoid valve. Do they all have them? Also, got a backfire when I put some fuel down the carburetor, then nothing.


#6

R

Rivets

With that engine,type and code numbers will be helpful.


#7

tom3

tom3

Do you know the history of that motor? Did it run last fall? When you rotate the engine by hand can you feel compression on both cylinders?


#8

B

bertsmobile1

jonvh said:
This is on a Briggs & Stratton 42E707, circa 1994. I don't see a fuel solenoid valve. Do they all have them? Also, got a backfire when I put some fuel down the carburetor, then nothing.
Click to expand...
So what happens with fuel down the plug hole ?
Backfire, through the carb or through the exhaust .
IT makes a difference and as per Rivets post the full number is really needed.
And have you checke tosee if the timing key in the flywhel is still in the right position ?
No need to pull the flywheel, just undi the fastener and check that both halves of the key slots make a perfect square .


#9

B

biggertv

jonvh said:
I've got a riddle for you:
"What has an engine that attempts to start, has a spark at the plugs, clean carburetor and air filter, gas in the tank, yet will not start up?"

Answer:
My lawnmower!

Ignition coil is good and I'm getting a spark. Fuel filter is clean and fuel is getting to the carburetor. I haven't pulled it apart to confirm, but when I spin the flywheel by hand, I can hear the valves opening and closing. I'm not sure that brand matters, but it's a Briggs & Stratton. Battery has good charge. Any idea of where I should start looking?

Thanks in advance, please let me know if additional information is needed.
-Jonathan
Click to expand...
Sheared Key. If it's too buggered up to fix, put flywheel in correct position, drill through fly and crank install roll pin or similar.


#10

jonvh

jonvh

bertsmobile1 said:
So what happens with fuel down the plug hole ?
Backfire, through the carb or through the exhaust .
IT makes a difference and as per Rivets post the full number is really needed.
And have you checke tosee if the timing key in the flywhel is still in the right position ?
No need to pull the flywheel, just undi the fastener and check that both halves of the key slots make a perfect square .
Click to expand...
Sorry, it's been a couple of days since I've been able to look at it again. When I put gas down the plug hole it backfires. Full number is 42E707-2631-E1. Would the flywheel key be sheared from top to bottom? I can view it from the top if I remove the large nut. It is square. But, obviously, I can't see the bottom of the key.


#11

B

bertsmobile1

As long as it looks dead square from the top the key is fine.
If it backfied with fuel down the plug hole then the valves are your problem


#12

jonvh

jonvh

bertsmobile1 said:
As long as it looks dead square from the top the key is fine.
If it backfied with fuel down the plug hole then the valves are your problem
Click to expand...
Out of curiosity and for future reference, how do you know it's the valves? Are they difficult to replace?


#13

PTmowerMech

PTmowerMech

jonvh said:
Sorry, it's been a couple of days since I've been able to look at it again. When I put gas down the plug hole it backfires. Full number is 42E707-2631-E1. Would the flywheel key be sheared from top to bottom? I can view it from the top if I remove the large nut. It is square. But, obviously, I can't see the bottom of the key.
Click to expand...

A sheared key will be even with either the flywheel keyway or the crankshaft keyway. A good key will be cross into the crankshaft keyway as well as the flywheel keyway.

Note to add: Sorry Bert. I posted this before I seen you're last post on this. Didn't mean to step on your toes.


#14

B

bertsmobile1

No need to appologise
two people saying the same thing is twice as good as one person saying it


#15

M

mikebarber

If you can see it from the top it is the same at the bottom Another poster asked if you had good compression just reading your post about hearing the valves open and close Locate a compression tester and see how much compression you have I have seen a small enging run with 60psi so you should have AT LEAST that much


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