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Briggs & Stratton 550EX won't run now

#1

S

slicer89

I was given a lawnmower to fix (Poulman pro) with the B & S 550EX motor with easy start, that would start and run fine, then die shortly after..... I figured dirty carb, no problem! Well, I took the carb apart and cleaned it thoroughly, didn't lose any parts, or mess up any seals.... Now the mower won't even start! I bought a new spark plug, and it's getting spark... but still not even trying to start.

I tried spraying carb cleaner down the carb to try to start it, still didn't work at all, and if I tip the mower over a little gas starts pouring out of the carb...

I checked the function of the float / needle, and it seems to work properly, it isn't sticking, or anything... and the rubber tip seems to be in good condition


any ideas? This mower is for someone who asked me to fix.


#2

S

shiftsuper175607

slicer89 said:
I was given a lawnmower to fix (Poulman pro) with the B & S 550EX motor with easy start, that would start and run fine, then die shortly after..... I figured dirty carb, no problem! Well, I took the carb apart and cleaned it thoroughly, didn't lose any parts, or mess up any seals.... Now the mower won't even start! I bought a new spark plug, and it's getting spark... but still not even trying to start.

I tried spraying carb cleaner down the carb to try to start it, still didn't work at all, and if I tip the mower over a little gas starts pouring out of the carb...

I checked the function of the float / needle, and it seems to work properly, it isn't sticking, or anything... and the rubber tip seems to be in good condition


any ideas? This mower is for someone who asked me to fix.
Click to expand...
Gasket missing? O-ring seal etc?
Linkages not connected?
Choke problem?
Try old spark plug.


It should TRY to start with starting fluid. You are spraying too much?


#3

M

mechanic mark

http://www.poulanpro.com/ddoc/PPOO/PPOO2016_NAen/PPOO2016_NAen_push_115587727.pdf

troubleshooting section

post all numbers from engine data plate, model xxxxxx, type xxxx, trim xx & code number.


#4

S

slicer89

shiftsuper175607 said:
Gasket missing? O-ring seal etc?
Linkages not connected?
Choke problem?
Try old spark plug.


It should TRY to start with starting fluid. You are spraying too much?
Click to expand...


No seals missing and in good shape, seated properly.

Linkages connected and straight, move freely.

Not sure.

Okay... Will get back to you.

I didn't spray that much, barely a squirt.


#5

B

bertsmobile1

Valve lash
blocked exhaust
stuck valve


#6

S

shiftsuper175607

slicer89 said:
No seals missing and in good shape, seated properly.

Linkages connected and straight, move freely.

Not sure.

Okay... Will get back to you.

I didn't spray that much, barely a squirt.
Click to expand...


choke open before spraying starting fluid....so it can get in the engine. Then close choke...try to start.


#7

S

slicer89

shiftsuper175607 said:
choke open before spraying starting fluid....so it can get in the engine. Then close choke...try to start.
Click to expand...


I did do that, it didn't seem to matter.

Like I said, It ran before I took the carb apart and cleaned it... It would just die shortly after.


And I can't get the valve cover off to see if the valve is stuck.... Just wouldn't make any sense because it ran shortly before.


#8

S

shiftsuper175607

slicer89 said:
I did do that, it didn't seem to matter.

Like I said, It ran before I took the carb apart and cleaned it... It would just die shortly after.


And I can't get the valve cover off to see if the valve is stuck.... Just wouldn't make any sense because it ran shortly before.
Click to expand...

Are you sure it is sparking?
I just worked on one....wouldn't start.
Put spark testor on it...no spark
tightened kill cable...it fired and start on first pull.


short story....must have fuel, air, spark


#9

pugaltitude

pugaltitude

This?

http://www.lawnmowerforum.com/showthread.php/37814-Briggs-amp-Stratton-engine


#10

S

shiftsuper175607

pugaltitude said:
This?

http://www.lawnmowerforum.com/showthread.php/37814-Briggs-amp-Stratton-engine
Click to expand...



Question has been asked before...nothing goes there. (little white plastic nipple)


Again....Are you sure you have a spark inside the combustion chamber?


#11

pugaltitude

pugaltitude

Yes but Briggs know they are having problems with it and are trying to rectify the problem.


#12

S

slicer89

I'm positive I do, I took the spark plug out and grounded it and turned the flywheel and it has spark. It just seems like no fuel is getting into the chamber, no matter how much carb cleaner I spray in their, I pull the plug and it's bone dry... so I am assuming I've got a stuck valve...

I just can't get the damn valve cover off.


#13

S

shiftsuper175607

slicer89 said:
I'm positive I do, I took the spark plug out and grounded it and turned the flywheel and it has spark. It just seems like no fuel is getting into the chamber, no matter how much carb cleaner I spray in their, I pull the plug and it's bone dry... so I am assuming I've got a stuck valve...

I just can't get the damn valve cover off.
Click to expand...

Just because it sparked when grounded outside, does not mean it does inside cylinder...probably is.
An inline spark tester verifies for sure.

But your dry plug is evidence...
If you pull plug and spray a little starting fluid in cylinder, replace plug...does it start momentarily?


#14

BlazNT

BlazNT

Just remove the valve cover. Rubber mallet, thin putty knife. Tap the valve cover with rubber mallet and if that does not wort work putty knife between valve cover and head till it comes off.


#15

M

Mikel1

shiftsuper175607 said:
Just because it sparked when grounded outside, does not mean it does inside cylinder...probably is.
An inline spark tester verifies for sure.
Click to expand...
How exactly does an inline spark tester tell you if it's sparking in the cylinder?


#16

S

shiftsuper175607

Mikel1 said:
How exactly does an inline spark tester tell you if it's sparking in the cylinder?
Click to expand...

Mikel1
Since you put it that why...I guess it doesn't.

I was think that if It was running and sparking it must be.
If motor is not running then, it does not give that indication.
So, in conclusion it is the fact that the motor is running is proof it is firing in the cylinder.
But, I have heard of plugs that fire by grounding to case but not under compression...is that true?


#17

M

Mikel1

shiftsuper175607 said:
Mikel1
Since you put it that why...I guess it doesn't.

I was think that if It was running and sparking it must be.
If motor is not running then, it does not give that indication.
So, in conclusion it is the fact that the motor is running is proof it is firing in the cylinder.
But, I have heard of plugs that fire by grounding to case but not under compression...is that true?
Click to expand...
Yes that is right.
I think your on the right track with trying the starting fluid in the cylinder.
You need fuel, compression, spark, and timing to run.:thumbsup:


#18

B

bertsmobile1

Mikel1 said:
How exactly does an inline spark tester tell you if it's sparking in the cylinder?
Click to expand...

If it is not passing from the plug to ground there will be no circuit so the tester will not light.

Back in the old days plug makers used to supply a testing machine which was a cylinder with a spark plug hole and a window to watch it.
You hooked it up to an airline then increased the pressure inside .
The plug was fired by a trembler coil so sparked continiously.
As you increased the pressure the spark started to break up then eventually went out because the spark did not have enough energy to jump the gap in the plug to complete the circuit to ground.

An in line tester will only flash if this circuit is completed.
What it will not tell you is if the spark is jumping the gap or running down the side of the electrode


#19

M

Mikel1

bertsmobile1 said:
If it is not passing from the plug to ground there will be no circuit so the tester will not light.

Back in the old days plug makers used to supply a testing machine which was a cylinder with a spark plug hole and a window to watch it.
You hooked it up to an airline then increased the pressure inside .
The plug was fired by a trembler coil so sparked continiously.
As you increased the pressure the spark started to break up then eventually went out because the spark did not have enough energy to jump the gap in the plug to complete the circuit to ground.

An in line tester will only flash if this circuit is completed.
What it will not tell you is if the spark is jumping the gap or running down the side of the electrode
Click to expand...
Inline testers in Australia must be different than in the USA. The inline neon tester can hang there ungrounded with other side into ignition coil and spark while turning over. I know this because I have done this.


#20

B

bertsmobile1

Do it in the dark and you will see where the path to ground is
Which is why you do not hold them in hand when using them


#21

S

slicer89

Man I feel sooo stupid... After cleaning the carb like 4 times, Replacing the spark plug, Taking the valve cover off (Got it off, Valves were working properly) cleaning this, cleaning that... Testing compression... I finally got curious and bent the kill switch / brake a little.. BAM! Started right up first pull....

This WHOLE time, the stupid kill switch wasn't properly disengaging and not allowing spark....


It runs now, Thanks for all the useful input. Mower runs like a champ now.


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