Sometimes it's not the usual stuff.

i386

Captain
Thread starter
Joined
Aug 24, 2004
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3,548
I've had a real time troubleshooting this little 20HP engine lately.

The engine ran poorly after rebuilding the carb. Naturally, I felt it was a fuel problem since that was the last thing I messed with. It's also hard to start sometimes.

The first thing I found was that I had an intermittent spark. My spark tester did not show this, but a timing light did. My points looked good, but upon further examination I found a problem with one of them. During manufacturing, the contacts on my points are inserted into a small hole on the points chassis. Then they press them which mushrooms the back side of the contact, effectively riveting it in place. Evidently, I had a bad one because the contact was loose. Intermittent spark solved.

Second thing. It's hard to start and still acts like it's not getting enough fuel (full float bowl, but dry plugs). I've pulled the carb more times than I can count and didn't find anything wrong. While I was messing with the points, I noticed some oil on the top of the engine so I pulled the stator plate to have a closer look. Turns out that the upper crank bearing cage screws were loose. Not only was it making a mess, it created a vent in the crank case that shouldn't be there. This affects the fuel pump and carb since they both rely on the vacuum created in the crank case.

Maybe someone will run across this and it'll help 'em one day.
 

mthieme

Captain
Joined
Oct 6, 2007
Messages
3,270
Re: Sometimes it's not the usual stuff.

There's one you don't hear everyday.
What year and brand is the motor?
 

Bigprairie1

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Joined
Jun 13, 2007
Messages
2,568
Re: Sometimes it's not the usual stuff.

Thats sounds like one of those elusive problems that would have been a financial killer if let to an average shop at standard shop rates.
Its good that you had the skill and wherewithal to troubleshoot this and figure it out.
(probably makes other troubleshooting/problems look easy now;):D)
Good Info.
BP
 
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