Generac standby generator - Propane - wont start??

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  #1  
Old 02-04-13, 05:41 AM
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Generac standby generator - Propane - wont start??

I have a Generac 4LM41A standby generator that I need help in troubleshooting and repairing. It is about 12 years old and hasn't been used much.It backs up our greenhouse and has been started every month and run for a while. The other day I went to start it while it will turn over it wont start and run. Ive tested compression in the engine as well as spark and both are good. Usually at this point I would look to fuel delivery. The unit was recently checked for gas leaks -none-, the electrical parts of the engine Generator , boards, etc were also passed as OK by a gas and generator technician respectively. None of these repair guys knows anything about the 4 stroke engine. I do, however have a good working knowledge of 2 and 4 cycle machines...just have never worked on one that was run by being supplied with propane..usually its gas or diesel. Can anyone give me tips on whats a good way to pinpoint the primary issue...if its the carburetor or something else??? The normal things I do to pinpoint the trouble (IE - pour gas in the spark plug hole ) obviously wont work here. The carburetor on this thing doesn't have a bowl to hold fuel..instead it has the propane gas line running directly into it and attaches through what looks like a cylindrical fuel solenoid. I dont want to have to replace this unit! I am confident I can fix it if pointed in the right direction. Please advise..and Thanks in advance for ANY help!
 
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Old 02-04-13, 06:57 AM
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If you've got compression and spark I think you are right about it being fuel. I would first verify that fuel is making it to the carburetor. Try turning the generator over/starting for a few seconds or however long you normally would to get it to start and smell the exhaust. If you don't smell propane I would first make sure there is propane in the tank and that the valve is open. Next I would look for a solenoid on the fuel line. If you have one it should open when you turn the key.

Is your generator fed gaseous or liquid propane? If it's fed propane in liquid form your should also have a vaporizer.

You can also put the generator in run condition and crack the fuel line loose at the carb and listen & smell for gas. If none comes out just keep working your way back to the tank until you find where the gas stops.
 
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Old 02-04-13, 07:01 AM
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Have you tried shutting off the propane supply and pour some gas in the spark plug hole to see if maybe it's getting too much propane?
Mike
 
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Old 02-04-13, 09:39 AM
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I have a 6500 Kubota dual fuel, using it on propane. After our power went out last week I went to start it and of course the battery was dead. I pulled a couple of times on it, then squirted a small amount of ether in the air intake grid. Started right up. It does take a while for propane to make it from your tank to the application since it is under very little pressure, so patience may help.
 
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Old 02-04-13, 02:51 PM
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People always want to blame the fuel system when a propane fueled engine won't start/run but in very few cases is it really the fuel system. Propane is rather fussy when it comes to ignition so you MUST have a good hot spark. This often means ignoring the original spark plug gap specification and instead setting the gap to 0.020 of an inch.

You can also put the generator in run condition and crack the fuel line loose at the carb and listen & smell for gas. If none comes out just keep working your way back to the tank until you find where the gas stops.
No. The propane ONLY flows to the carburetor when there is a negative pressure (vacuum) developed on the diaphragm of the zero-pressure governor. Disconnecting the line at the carburetor will only prove that the zero-pressure governor has failed IF there IS propane present.

You MAY have a problem of compressor oils congealing in the zero-pressure governor or piping to the carburetor but such usually requires a LOT of use, literally hundreds of gallons of propane. This is rather doubtful on a standby generator.

IF a propane system has not been used in quite a long time it might be simply a lack of fuel to the zero-pressure but I would start with the spark plug.
 
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Old 02-04-13, 03:50 PM
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Furd, good to know about the spark plug gap thingy. I'll do that next time. Maybe I won't need the ether. Mine went straight from gas to propane with no adjustments like what you suggest.
 
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Old 02-05-13, 02:31 PM
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Just wanted to let the OP know...the company posted a request to call them for help. Unfortunately the username and such violated Forum rules so it had to be deleted.

Might want to give them a call.
 
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Old 02-05-13, 03:56 PM
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The "OP"? not sure what this refers to..please advise.
 
  #9  
Old 02-05-13, 04:00 PM
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Original Poster...or Original Post....depending on context. In this case it's you.
 
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Old 02-05-13, 04:03 PM
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Thanks, that's what I figured.
 
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