Generator Tune-Up - What Have I done?

[Fred McKenzie]

A 2500 Watt 120V power generator (Powermate Proforce PM0102500) seems to
be working fine, but engine sounds a little rough. Why not touch up the
carburetor adjustment and see if that improves it?

First I turned the screw on the carburetor to the right. Some resistance
to turning, but absolutely no difference in engine speed or sound.

Then I turned the screw to the left. Screw is quite loose and still no
difference in the engine, but now I have gas leaking from the bottom of
the carburetor! I turned the screw to the right until snug, and the gas
leak has stopped.

There is no other adjustment visible on this carburetor. Is that screw
intended to drain the carburetor, or have I seriously messed up something?

I've searched the web for data, and only found that the 5.5 HP engine was
made by "Sumec". I gather that they make motorcycle engines, but found no
carburetor data.

Fred

 

[Ancient_Hacker]

Well, if the screw is about a #8 and has a o-ring and pointy end and
screws into the main body of the carb, it probably is a mixture
adjustment screw.

If it's bigger, has a flat rubber or fiber washer, and screws into the
float-bowl, it's probably a drain screw.

In any case you'llprobably get better answers on a small-ening
newsgroup, not an electronics group.

 

[Michael Kennedy]

In any case you'llprobably get better answers on a small-ening
newsgroup, not an electronics group.

Probably true, but there are all kind of guru's here that know all sorts of
things.. I once asked abou the best way to make a glass beer bottle into a
drinking glass / tumbler and got lots of answers here and almost no answers
in alt.rec.glass.cutting or whatever the group is for that was.


Answer to the original,

As Ancient Hacker also said...
I'd guess that the screw you turned was just a bowl drain since it was tight
when you tried to turn it to the right. Many small carbs have them, and you
probably havn't messed anything up.


-Mike

 

[Fred McKenzie]

As Ancient Hacker also said...
I'd guess that the screw you turned was just a bowl drain since it was tight
when you tried to turn it to the right. Many small carbs have them, and you
probably havn't messed anything up.

Mike-

The screw is located on the side of the carburetor, but at the very
bottom. Your comment that "many small carbs have them", reinforced by the
fact that gas did drain, leads me to think everything is OK.

Following Ancient Hacker's suggestion, I searched for a more relavent
newsgroup. A semi-close match was rec.motorcycles.tech, where I posted
again. Today there are a couple of responses there that don't seem to
address the carburetor! One refers to an article from the Journal of
Personality and Social Psychology entitled, "Unskilled and Unaware of It:
How Difficulties in Recognizing One's Own Incompetence Lead to Inflated
Self-Assessments".
(http://www.apa.org/journals/features/psp7761121.pdf)

Those motorcycle guys sure are an intellectual bunch!

Fred

 

[Michael Kennedy]

Following Ancient Hacker's suggestion, I searched for a more relavent

newsgroup. A semi-close match was rec.motorcycles.tech, where I posted
again. Today there are a couple of responses there that don't seem to
address the carburetor! One refers to an article from the Journal of
Personality and Social Psychology entitled, "Unskilled and Unaware of It:
How Difficulties in Recognizing One's Own Incompetence Lead to Inflated
Self-Assessments".
(http://www.apa.org/journals/features/psp7761121.pdf)

Those motorcycle guys sure are an intellectual bunch!

I see that you had about the same experience that I did with the glass
making / cutting community.


- Mike

 

[James Sweet]

A 2500 Watt 120V power generator (Powermate Proforce PM0102500) seems to
be working fine, but engine sounds a little rough. Why not touch up the
carburetor adjustment and see if that improves it?

First I turned the screw on the carburetor to the right. Some resistance
to turning, but absolutely no difference in engine speed or sound.

Then I turned the screw to the left. Screw is quite loose and still no
difference in the engine, but now I have gas leaking from the bottom of
the carburetor! I turned the screw to the right until snug, and the gas
leak has stopped.

There is no other adjustment visible on this carburetor. Is that screw
intended to drain the carburetor, or have I seriously messed up something?

I've searched the web for data, and only found that the 5.5 HP engine was
made by "Sumec". I gather that they make motorcycle engines, but found no
carburetor data.

Fred

That sounds like the banjo bolt that holds the float bowl on. If you
loosen it up go figure fuel will leak out.

 

[Fred McKenzie]

That sounds like the banjo bolt that holds the float bowl on. If you
loosen it up go figure fuel will leak out.

James-

There is a hex-head bolt on the bottom that probably holds the bowl in
place. The subject screw is on the side near the bottom, screwing in
towards the center of the bowl. It has a small hole on the bottom of the
tube it screws into, that appears to be the drain.

I ran the engine with the fuel valve shut off and choke on, to run out as
much fuel as possible. I removed the screw and there was still a few
drops of gas that drained.

The screw has a relatively sharp point and has a spring to keep it from
vibrating loose. In other words, it looks just like needle-valve
adjustments on other carburetors.

Someone on the rec.radio.amateur.equipment newsgroup posted a link to
http://www.smokstack.com/ which has forums on small engine and generator
set repairs. If I have any additional problems, that looks like a good
place to find help.

Fred

 

[James Sweet]

James-

There is a hex-head bolt on the bottom that probably holds the bowl in
place. The subject screw is on the side near the bottom, screwing in
towards the center of the bowl. It has a small hole on the bottom of the
tube it screws into, that appears to be the drain.

I ran the engine with the fuel valve shut off and choke on, to run out as
much fuel as possible. I removed the screw and there was still a few
drops of gas that drained.

The screw has a relatively sharp point and has a spring to keep it from
vibrating loose. In other words, it looks just like needle-valve
adjustments on other carburetors.

Someone on the rec.radio.amateur.equipment newsgroup posted a link to
http://www.smokstack.com/ which has forums on small engine and generator
set repairs. If I have any additional problems, that looks like a good
place to find help.

Fred

Hmm that really does sound like the needle valve, be careful not to
crank it down too tight, you can squish the tip. It may be for the idle
mixture if the engine still runs fine.

 

[Michael Kennedy]

Well I'd say it sounded like a needle valve too except that it was tight to
start with and when you open it gas pours out.. Does the gas come out some
sort of line or hole in the carburator or does it pour out the hole where
the screw is?

An easy way to find out what that screw does is simply to remove it.. If it
is a needle valve it should come all the way out and look kind of like a
needle and be pointed on the end.. If not you'll probably have gas running
allover the place.

If it is running correctly now I wouldn't touch it though. Too much
potential to make it not run. If anything I'd take the carb and have it
cleaned or rebuilt at the local mower shop if it doesn't appear to have any
other screws on it.

- Mike

 

[Fred McKenzie]

Well I'd say it sounded like a needle valve too except that it was tight to
start with and when you open it gas pours out.. Does the gas come out some
sort of line or hole in the carburator or does it pour out the hole where
the screw is?

An easy way to find out what that screw does is simply to remove it.. If it
is a needle valve it should come all the way out and look kind of like a
needle and be pointed on the end.. If not you'll probably have gas running
allover the place.

If it is running correctly now I wouldn't touch it though. Too much
potential to make it not run. If anything I'd take the carb and have it
cleaned or rebuilt at the local mower shop if it doesn't appear to have any
other screws on it.

Mike-

It is a needle valve. There is a small hole, perhaps an eighth of an inch
diameter, located on the bottom side of the bowl where the needle valve
screws in. Yes, gas leaks when the valve is unscrewed, even before it is
removed.

There is a paragraph in the owner's manual that says to drain the
carburetor before storing the generator for a long period. However, it
doesn't say anything about how to do it. I'm hoping that the subject
needle valve is intended for that purpose!

I have an old Sears/Generac carburetor that has two such valves, and the
owner's manual gives instructions on how to adjust them. One is for
no-load and the other for full-load, according to the procedure. The one
on the Powermate generator doesn't behave like either of the ones on the
Sears/Generac. The engine sound doesn't waver when it is adjusted for
either load or no load, and there is never any black smoke from the
exhaust.

For the moment, I plan to leave it alone, as the generator seems to be
functioning OK. I think the "rough" sound may have smoothed-out after
running for a while.

Fred