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Craftsmen Bob vila

#1

G

g350h

Just picked up a craftsmen Bob Vila 21 HP. Only running on one cylinder, tried changing coils no difference. The cylinder that's running I checked the plug wire is getting good spark, the cylinder that isn't running the wire has no juice when connected to the plug, when I disconnect the wire from the plug, the wire has juice. With engine "one cylinder" running, the non running side with plug out is sparking when held to side of engine. seems like it shorts out when plug is in hooked up normally. Also tried a new plug. Thanks for any help.


#2

N

noma

Morning g350h

Welcome to L M F Just wondering if the spark plug wire connection is good on the end of the spark plug wire that clips to the spark plug? Maybe put a new end on the plug wire and see if that helps, could be a bad connection , broken wire.:licking::thumbsup:


#3

G

g350h

noma said:
Morning g350h

Welcome to L M F Just wondering if the spark plug wire connection is good on the end of the spark plug wire that clips to the spark plug? Maybe put a new end on the plug wire and see if that helps, could be a bad connection , broken wire.:licking::thumbsup:[/QUOTE


The plug gets great spark when not in the cylinder.
Click to expand...


#4

B

Buckshot 1

:smile: Evidently its not firing under compression on that side, try another new plug.


#5

G

g350h

The plug gets good spark when not in cylinder. Tried a new plug, no deal.


#6

C

chance123

Try putting a few wraps of electrical tape on the plug wire. Just a tiny unseen crack in that wire could spark a connection and short out.


#7

G

g350h

chance123 said:
Try putting a few wraps of electrical tape on the plug wire. Just a tiny unseen crack in that wire could spark a connection and short out.
Click to expand...



I should have mentioned that I also switched coils with no luck. The engine is a Briggs Intek 21 HP. Model # ybsxs.7242vf
I tested the plug wire with an inline tester.did not do compression test yet, probably wed. Stumped on why losing power on plug wire when hooked to spark plug.wondering if there are any safety switches that may have it run on one cylinder? Any suggestions greatly appreciated. Thanks again.


#8

C

chance123

This has me wondering. Perhaps it "is" sparking when in the engine, but just not running on that cylinder. A compression test on that cylinder will reveal a lot. You could have a hung up valve. Just 3 weeks ago I had a similiar situation. It turns out that one of the tiny screws that secures the throttle butterfly to the throttle shaft came loose and got ingested into the engine. The compression was zero on that cylinder and when I opened it up I found that tiny brass screw wedged between the exhaust valve and seat. The brass was soft and the valve & seat were fine. Buttoned it back up and all was OK. I have seen those tiny brass screw come loose and get ingested quite a few times.


#9

G

g350h

Well just pulled the head, piston isn't moving, guess broken rod. Pulling the motor and digging in deeper to see if its fixable. I'm sure I'll be asking for some advice on this one. Thanks for all the help guys.


#10

B

Buckshot 1

g350h said:
The plug gets good spark when not in cylinder. Tried a new plug, no deal.
Click to expand...

:smile: I understand that, with the plug installed it may not be firing under compression. Tried new plug, in or out of the engine. Also like stated, what is the comp on that side?
Dis-regard this post, I did not read the post past this your above reply,before posting this reply. But the plug was not firing under compression, because there was no compression.


#11

G

g350h

Buckshot 1 said:
:smile: I understand that, with the plug installed it may not be firing under compression. Tried new plug, in or out of the engine. Also like stated, what is the comp on that side?
Dis-regard this post, I did not read the post past this your above reply,before posting this reply. But the plug was not firing under compression, because there was no compression.
Click to expand...

Just got the motor off yesterday, going to try to dig into it this week to find the problem. I'll keep u posted.


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