jarhead331
I have a Guardian serial #3728403 that starts for it's weekly test and shuts down after about 10 seconds and then starts again and runs for another 10 seconds and finally shuts down with a overcrank message. Any thoughts?
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cookelec
Check the oil pressure and oil pressure switch.
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Peddler
I would check for AC output while it is running.  That is an old unit and may get it's run signal from the AC output via the 66 wire which would possible make it think it hadn't started.  Oil pressure and over heat are latching faults and it would not try to restart with those.  If you have good voltage to the breaker while it is running then I would check the switch to make sure it doesn't have water in it which can cause some screwy faults.  If all that checks out it is most likely the control board.
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Steve H
I've had this problem with mine for 2 years.  Lemme guess,  It starts up normally, but it sounds like it's starving for gas.  It times out, like you said, and starts the 2nd time. 

Everything mentioned has been done plus, New regulator, raise of gas line pressure, and most recently, a check valve in the gas line.  I forget it all.  If it were the oil pressure, it woukd not start at all.   Nobody here seems to know what the problem is.  It's definitely a gas problem between the valve and the carb intake.  I'm starting to think the shut off valve needs to be moved to the carb side.

I have a question.  Is your generator subject to winds?  Something is evacuating the gas between the regulator and the carb.  OR  The solenoid valve isn't opening properly.  Mine has some partial miss fires like it's running a tad lean.  I learned Natural gas old school.  
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murphy
Does the engine have a rubber bellows between the air box and the carb?  If it does, inspect it very carefully.  You may find that the bottom of the folds are full of holes.  Mine looked fine until I spread the folds apart and then it looked like swiss cheese.
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MacL
As Peddler said, this is probably an "Undervoltage".  Check the output during the 10 seconds.  Leg to leg should be 247-250 volts (typical, depends on the model).  You can check this voltage under the cover of the generator on the circuit breaker, or in the transfer switch on the front bottom lugs.  One leg to neutral should be half that.  You'll likely see less than 2 volts.

You may also be hearing a scraping metallic noise, which would be the starter not disengaging due to no voltage output.  If the red light is flashing it is NOT whatever it states on the panel.  So a flashing overcrank is not actually an overcrank.

Let Peddler know what the voltage output is.
State your problem, not your diagnosis.
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jarhead331
Thanks everyone for your help. I will look into your suggestions and let you know.
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Steve H
murphy wrote:
Does the engine have a rubber bellows between the air box and the carb?  If it does, inspect it very carefully.  You may find that the bottom of the folds are full of holes.  Mine looked fine until I spread the folds apart and then it looked like swiss cheese.


I don't have the bellows.  All voltages are good when running.  It's like there is not enough gas between the regulator and the carb for the initial start up.  The engine doesn't get up to speed so I can see a dozen reasons for it to shut down.  Since it's not oil pressure, it times out for X number of seconds, (Like 10 seconds) and then starts up normally.

Only once have I heard this thing start like it should.  That was right after the gas pressure was raised 1/2 a pound.  That's what lead me to believe something was sucking the gas back out of the line.  Apparently not.

I'll be dead by the time this gets figured out
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grsthegreat
how much pipe, and how large of a pipe is there between generator and fuel regulator. I have run into a few units that didnt have much of a pipe, and did not have the surge capacity necessary to fire up the generator. on one unit we relocated the regulator and added 4 feet of 1" pipe between generator and regulator and this fixed the unit.
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sggoat
One of the prime t'shooting tools is to know "what has changed"? If the unit was exercising ok before(and loading as it should when power was lost) then there is something going on that is deteriorating over time, especially if you are seeing a slow reduction in performance. The holely bellows is a good example of this.  If the unit just suddenly started this behavior, then it might indeed be the breaker(or the generator stator--[you would get the overcrank error on this just like I did on my 14KW]
What is unusual is the engine does not get up to speed, so that would tell me the fuel delivery system may be suspect--the electrical components would need to see the full rated rpm before they told the unit to shutdown due to low output/low excitation,etc.
Just my layman's thoughts--
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Steve H
There's less than 30 feet of 1" between the supply and the genset.

sggoat  This has been doing this since the gen was replaced with the newer unit back in 2016.  Our old 15KW rolled over and played dead cockroach after 16 years of hard service.  Including 5 weeks of Hurricane Sandy.  Except for controller failures it never failed until the bearing went in the generator portion.  The new 22K was installed and electrically retrofit to the old system.  Everything else remained the same.  I've replaced the regulator, installed a check valve in the gas line, raised the system pressure and it still starts and stalls, only to start right up after a time out.
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78buckshot
Steve H, has anyone checked the ignition system? specifically looking for good spark at both cylinders? Some of the symptoms sound like it may be running on one lung. I found no spark on a 3 year old unit - I think it never ran right from day one - only running on one cylinder, it would start and slowly get up to speed but could not carry a load, one spark plug looked brand new, I believe it had never fired.
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coreyb38
Check your regulator to make sure there is not 2 step down regulators in line working against each other. If gas pressure is stepped down at the supply and again down line it would cause a similar issue 
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Steve H
78buckshot wrote:
Steve H, has anyone checked the ignition system? specifically looking for good spark at both cylinders? Some of the symptoms sound like it may be running on one lung. I found no spark on a 3 year old unit - I think it never ran right from day one - only running on one cylinder, it would start and slowly get up to speed but could not carry a load, one spark plug looked brand new, I believe it had never fired.


Yes I did that already.  That's a pretty nasty spark coming off those coils.  Also, I loaded it up with a 5HP air compressor, and a 3.  There are no partial miss's as it runs and maintains voltage.  It did struggle quite a bit on the 5HP startup.  I listened to the engine closely, it's didn't miss a beat
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Steve H
78buckshot wrote:
Steve H, has anyone checked the ignition system? specifically looking for good spark at both cylinders? Some of the symptoms sound like it may be running on one lung. I found no spark on a 3 year old unit - I think it never ran right from day one - only running on one cylinder, it would start and slowly get up to speed but could not carry a load, one spark plug looked brand new, I believe it had never fired.


Sorry, I just learned how to find my history posts.  Got some back reading to do.  Thanx
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