# Generator Surging / Pulsing



## Murphy625

Hi folks, I'm having an issue with my home generator surging and pulsing. Its a coleman 5000 with a 10hp Techumseh engine. 
I bought this unit used about three years ago with a dirty carb. I took it apart and cleaned the carb, ran a tank of good gas with extra carb cleaner through it and it began running great. I've used it 4 or 5 times in the past three years and it always starts easy and runs smooth. I always add a bit of carb cleaner and Stab-IL as well as a drop or two of Lucas Oil to every tank of gas.. I do this for all my small engines around here as it has greatly reduced maintenance issues on everything from the chainsaws and log splitter to the mower and leaf vacuum. (that ethanol is a pain in the rear!) 

This past weekend, we had a big windstorm in Michigan and we lost power while the temps dropped into the low teens and some single digits. The generator ran fine for a while, then started acting up. It is pulsing.. 

When it first started doing it, I was able to close the choke lever just one notch from wide open and it fixed the problem. Then the problem slowly returned. Research on web almost always blames the carb.. I had an emergency new spare carb on the shelf just for this generator. No change.. generator still pulsing. (It was a lot of fun replacing it in the dark, at 10 degree's F last night) 

I noticed that if I place my finger on the governor linkage and sort of stop it from oscillating every second or so, it will steady out and run smooth for 20 or 30 seconds when I take my finger off.. I also tried adjusting the idler screw so it could not idle below 125 volts @ 62hz. (I have a fluke meter to measure this stuff) 

Adjusting the idler screw seems to have helped but it is causing the generator to idle higher than it should under no-load and it still want to pulse sometimes. The generator seems to also run smooth if I turn some appliances on and place it under load. When 

I turn on the toaster, the output voltage drops to 110 volts and 59hz. Something else I found odd... The pull cord to start the engine is unusually hard to pull.. I am almost certain this is because of the extremely cold oil as it gets easier to pull the start cord once its warmed up. It only takes two pulls to cold start the engine at 12 degrees. As I spent 14 hours messing with this thing on and off, it seems to me that it was giving me more problems as the night wore on and the daytime temps of 24 deg dropped to nighttime temps of around 10 degrees. Anyone ever hear of temps affecting a generator? All help is appreciated. Thanks!


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## Basementgeek

Hi and welcome to TSF:

Try here:

Carburetor Problems and Solutions

Make sure you check the gasket(s) on the intake, check the bolts/studs.

I can understand not running their very best when it is cold as the carb has no heat around it.

BG


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## Murphy625

Basementgeek said:


> Hi and welcome to TSF:
> Try here:
> Carburetor Problems and Solutions
> Make sure you check the gasket(s) on the intake, check the bolts/studs.
> I can understand not running their very best when it is cold as the carb has no heat around it.
> BG


So after I took off the original carb and put on a brand new carb and the thing has the same problem, you still think its the carb?

Please educate me on why you still suspect a carb problem...

Also, there are no adjustment screws on the carb.. just an idle screw.
Gasket was new with new carb.


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## Basementgeek

As to why I thought it was carb problem, because it sounds like it. Understand nothing you can do since it has no adjustments.

Make sure the intake bolts/studs are tight. It could be leaking and causing a lean condition. Don't forget the bolts holding the intake to the block.

I would not worry about the surging under no load. I have a small 1400 watt that does a lot of surging, with load. Apply a good load and it runs great.

Also try running with the air cleaner off as a test.

BG


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## Murphy625

Manifold bolts are all tight, Tried with air cleaner removed and no change. What a pain in the rear......


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## Basementgeek

I myself would not mess with it until it warms up some. I have never needed mine when it is this cold. It could just be the cold.

BG


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## Christo1

Sorry to bump an old thread, but exact same problem as above, even same Tecumseh 10HP engine. Not sure it was addressed.:banghead:

Sometimes engine starts and runs smoothly with partial choke, but then stalls after a while or not. And if I stop ad then restart a few minutes later, it surges and nothing I can do to stop it. I actually have 2 generators that do this, one with original Tecumseh carb and the other with a new aftermarket. And they do the same thing! I have fresh has with 'Mechanic in a Bottle' and stabilizer in it.

Was this resolved, and if not, any suggestions?


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## AVB

First you need to determine if it is a carburetor or governor problem. Find the throttle butterfly. While holding it steady does it smooth out or just dies out? If it smooths out then it is a governor problem and probably just the static adjustment off. If it dies then it is carburetor related which of today's epa carburetor are a little too lean would need a slight resizing of one of the jets. THis depends which carburetor involved as which can be resized.


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## El-Maquinista

I had the same problem. I put a kit in the carburetor last year, new gaskets around the carburetor intakes, new fuel lines, and new gas. This may sound silly but mine smoothed right out after I changed the spark plug and the nasty oil. My runs great now. I thought, impossible. I don't use the thing often enough to dirty the oil but it was nasty. It made all the difference and now it holds a steady 125 volts. If someone has an idea about how to make it run quiet, I'd appreciate it.


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