Generac Generator Electrical or choke trouble?

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  #1  
Old 08-25-07, 04:00 PM
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Generac Generator Electrical or choke trouble?

I have a generac in my RV that has been surging a little lately. I noticed that the choke(electric) wasn't moving at all and that if I manually held it about half closed it would run fine. After reading up I discovered that the choke should really only close when it starts(which it doesn't).

Meanwhile, I cleaned off/out the carb. with some spray cleaner and it smoothed out.

I decided to test the choke with my meter and didn't get any reading so I followed the wires back to the main + and - that come directly from the battery. Problem is that when I test them, they test backwards! I followed them back to the battery where they test fine. Could there be a problem with the junction(not sure what it's called) where those wires and several more come together on the generator? Can anyone suggest anything I can test next?

By the way, after running smoothly for probably more than an hour, the surging started back again. I don't know if that can be caused by some kind of electrical problem or not.

I'm getting more confused the more I look into it so any help is appreciated.

 
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Old 08-25-07, 05:31 PM
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I'd like more info on your motor before throwing my guesses out but here goes so far....I'm thinking your surging and choke problems are two different things. Your first carb cleaning worked until whatever else broke loose in there and made the carb 'dirty' again. As we stand right now I would do a complete cleaning of the fuel system. When you run it half closed that means it is needing more gas. How old is the gas, how often is this used?

Beyond that I want to try to see your wiring diagram or at least what you have before throwing more out there. How did you test the choke and how does it test backwards? Post back with some numbers please.
 
  #3  
Old 08-25-07, 06:04 PM
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Ok good. This is a Generac NP-45G (4.5 kw).

The gas is probably 3 or 4 months old. It's not been used very often but it hasn't been sitting for a year with no use or anything.

I saw 2 wires going to the choke that were both blue(for what it's worth). I put the positive lead on each one of those and the negative on the main ground. Whether the generator was running or off these tested backwards(the needle went backwards from 0). I got the same results when testing the main power lines from the battery. When I reverse the leads (+ on - and - on +) I get 12V both on the main lines and on the 2 choke wires. When I put the + lead on either choke wire or on the main + wire and I put the - on another ground anywhere, I get nothing. Also, when I test the other end of the main wires(connected to the battery) they test correctly. Seems like the polarity is being reversed inside this thing somehow...but then again if I knew what was going on I wouldn't be bothering the experts

By the way, as I started writing here (probably 3 hours since I ran it last) I went out to get the Model # and cranked it back up again... now it's purring like a kitten... but still no choke.
 
  #4  
Old 08-25-07, 06:20 PM
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Let me add one more piece to the puzzle. Still running great when I went out to turn it off but I've noticed that it wants to keep running just a little bit longer when I try to turn it off. I have to hold the stop button down longer than I used to while it sputters and finally quits.
 
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Old 08-26-07, 07:04 AM
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You have a fuel restriction, most likely in the carb. This is causing a lean condition which will show as surging. Also when you go to shut it off, the extra heat created by running lean will cause detonation (run on) IE: the fuel/air mixture is continuing to burn from the heat rather than spark from the plug.

I do not think your choke is a problem. Without a schematic and or manual, its hard to know what readings you should have where and when....?

Also replace the fuel. Depending on your storage practice, gas can go bad in as little as a few weeks. Any contamination, water or debris, can also cause this.

Remove and service the carb and start with fresh gas.
 
  #6  
Old 08-26-07, 01:30 PM
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Ok. I'll do that. Can you give me some direction in regards to servicing the Carb.? I've never actually taken it off to clean it. I know you can soak it in something but beyond that I just need a little direction. What can I use to soak it? Is there anything in particular I'm looking for? What do I need to take apart or should I try soaking it as a whole first?

I'm assuming that the choke doesn't have anything to do with the surging trouble but isn't it supposed to come on when I start it? If I try to start it cold I end up having to manually close the choke. Do you know a good place where I could look for a diagram for this one?
 
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Old 08-26-07, 06:27 PM
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I've been looking for a while and still can't find anything on 'Generac NP-45G'. I can't even find the generator much less what type engine is on it. Keep in mind I'm just a guy at home trying to help but is there any more information on the generator and espicially the engine? I still hesitate to guess more until knowing what you have. I am guessing it is a float carb and you can search this forum and find all kind of information on cleaning such.

For more detail I need more detail.
 
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Old 08-27-07, 03:42 AM
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I like to use a Napa product, part number 6402, to soak the carburetor in once the carb is off and disassembled, making sure to remove all rubber and most plastic pieces from the carb body before soaking as the bath cleaner will deteriorate these parts. You will then want a Generac carb rebuild kit and new mounting gaskets and a new air cleaner gasket. This will be in addition to the thorough fuel system flush that Fixit mentioned doing. As for the choke, since it is an electric choke and not a temperature activated system, then, yes, it should activate upon initial cranking. But since I don't know RV setups at all perhaps there's something more to the system than I am aware of. And, without a schematic, it would be impossible to acurately diagnose your trouble with this. I'd recommend consulting a local RV repair center for their opinion on this matter. Ideally, the choke should not activate with a warm/hot engine as it would not be necessary to start the engine, only when the engine is cold.
 
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Old 08-27-07, 04:45 PM
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Ok. I got through to Generac today and they located 2 manuals for me that apply to my model:

a diagnostic repair manual...

http://www.guardiangenerators.com/PublicPDFs/75239.pdf

and the service manual...

http://www.guardiangenerators.com/PublicPDFs/86640.pdf

the guy on the phone said the + and - wires should definitely not be testing opposite like that so he wanted me to take the manual and make sure the connections all matched which I am doing now.
 
  #10  
Old 08-27-07, 05:26 PM
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Ok I just made a discovery that I should have made early on I guess. The reason that it starts out surging and then smooths out a few minutes later is that there's a delay before the a/c comes on inside the RV. As soon as there's an electrical load on the generator, it runs fine. When I turn the breakers off, it starts surging again. Flip them back on and it surges until the air comes on inside and it immediately runs fine. Does that tell us anything different?
 
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Old 08-28-07, 12:31 AM
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It still means the carb needs cleaning. I don't see how the polarity can be showing negative on the choke wires and positive on the ground...if it was this way, the battery would be shorting out and dead within a short time. Not to mention the wires that would be burning.
 
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Old 08-28-07, 06:28 AM
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I agree with cheese, are you sure your leads are connected to the meter correctly...

don't let the smoke out of the wires, they dont work very well when the smoke gets out
 
  #13  
Old 11-05-07, 10:34 AM
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What ever happened with this? I, too, thought replacing the fuel might be a potential solution...but the thread just kind of died out.
 
  #14  
Old 11-05-07, 10:57 AM
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I actually had to start on something else and have not been able to clean the carb or replace the gas just yet. I will say this... I've driven it since then and the engine runs fine. I know the gas comes from the same tank. I don't know if this tells us what we need to know about the gas or not but I would think it would have to be a good sign.... right?
 
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Old 11-05-07, 08:09 PM
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Right.


I had to type this sentence because the above message was too short and caused a warning message. Now it's long enough.
 
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