3Phase
11KW Model G0064383  Ser 3000171105 Running Nat Gas  I’m on Northern Ohio

Red light was on after weekly test.  Unit had low rpm code 1603 and a under voltage code 1900. 

I was able to start the unit and it was running real slow.  I manually actuated the butterfy valve and was able to get it to run faster. Let it run for 15 min and turned it on AUTO.

Today I tried to start the unit and it was running real slow again.  Error code 1603 again. Manually was able to get it to run faster.  It was bogging everytime I moved the butterfly valve but it kept running.  I let it run for 40 min.

Air filter is new and wasn’t frosted up.  

How to check the stepper motor? How to check gas flow after gas enters the uunit? The LP/NAT GAS was in the NAT GAS position. 1 1/4” gas line supplying the unit and gas flows freely to the unit.

Any ideas?

thanks


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3Phase
The unit was installed in 2016 and has very low running hours.  All the time on it has been the weekly testing....
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DenisC
Have the valves ever been adjusted?
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78buckshot
Stepper motor resistance check, unplug the connector from the controller, check resistance between red and each other color - should be approximately 10 ohms except to black, no continuity between any of them and ground/case.
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3Phase
I did the valves last year with the oil change.  

Thanks, I’ll check the stepper motor.

Nothing else comes to mind on these symptoms?
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78buckshot
Other possible causes could be bad controller, loose stepper connection at the controller, engine running on one cylinder, incorrect gas volume and/or pressure. With a cold engine remove the spark plugs and see if they look the same color, then adjust the valves, the valves have to be adjusted to .004" cold with piston at top dead center for the cylinder your adjusting. Button up the valve covers and attach the plug wires to the plugs and lay the plug on the valve cover/ lifting lug so as to ground the threads on the valve cover, turn the gas off at the gas cock and crank the engine with the starter and look for spark at each plug. To check gas pressure will be another set of instructions, we'll do one step at a time.
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3Phase
Thanks.  I’ll look it over.
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3Phase
On the stepper motor, all of the wires INCLUDING the BLACK had 10-11ohms from the red wire.  No wires had continuity to ground.

Valves, spark plugs, and sparking is all good.

I tried to start it and it was running slow but smooth.  Using my finger I raised the speed slowly and then all of a sudden the stepper kicked in and took over. Runs fine.  Not trying it under load though.

New stepper?  P/N?
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78buckshot
Yes I'd say new stepper, call Ziller, they will get one in the mail ASAP.
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3Phase
It’s after hours and there is no answer.  It looks like the stepper is on this assembly 0K6091.  Do I have to purchase the whole assembly or is just the stepper available?
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Geoff Z
0K6091 is the correct mixer assy for your unit. The exploded view does not show a separate part number for the stepper. We typically find that means you must purchase the entire mixer assy. We will confirm with Generac tech right away on Monday morning. It does show stock at the factory and we will check our inventory as well.
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3Phase
I replaced the mixer assembly.  

When I push manual starting the servo moves the butterly valve to slow then fast as the generator is starting.  The old stepper didn’t do this.  The generator runs faster but ever so slightly slower that it should.  I get 1603 error.  

If I push my finger on the butterfly valve and make it run faster, the stepper rotates and wants the engine to run slower. I let go of the butterfly and it runs fine after the motor slows down and the stepper takes over. No error.  

I shut off and re satrt and it sounds close to normal speed but I get the 1603 error...  Ideas?
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Peddler
Do you have a frequency meter to check the Hz?  The speed is controlled by the signal off the 18 wire to the mags.  I have seen one mag unhooked and it will make a dramatic overspeed but never seen a slight underspeed.  I wonder just how far off it is?  I wonder if what ever took out the stepper took out the controller as well. 
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3Phase
I don’t have a meter.

I let the generator run for 1/2hr.  I shut it off and turned it back on. The stepper motor didn’t go slow and fast on start up this time.  Close to running speed but got 1603 error again.....
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3Phase
New controller P/N 0J8371C ?
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3Phase
Rev Q the latest?
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Geoff Z
You don't have a meter. Are you a Generac Tech? This unit is still under complete warranty.
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3Phase
No not a Tech.  ButI’ve installed 5 of the 11kw units.....   And mine is the one screwing up!!
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Geoff Z
Totally understand but you won't be paying for parts and labor if you have an Authorized Dealer come out.
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Peddler
I'm going to say a controller but It is easier for me because I can try one and if that doesn't help it goes back into inventory.  I had one of these that something took out the controller and the stepper at the same time, lighting I guess.
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78buckshot
I am unhappy with the stepper motors as of late. I have replaced three in a 17kw in a year and a half. Tech support can't explain why, they said to replace the controller if a new stepper acts strange but I can't condemn the controller once I replace the stepper - it runs correctly. I did replace the controller several years ago for reasons I can't remember right now.
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MacL
Wow.  I think it's time to cut your losses.  This warranty started on 8/10/18....  you could have a tech fix it for exactly $0.  What the hell are you doing?  You don't even have a meter!  Call an authorized dealer.
State your problem, not your diagnosis.
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3Phase
I hear ya.
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