GEN 0047440 20KW 09/07/04 LP

Generac, Guardian, Honeywell, Siemens, Centurion, Watchdog, Bryant, Olympian & Carrier Liquid Cooled Home Standby & Commercial generator troubleshooting and repair questions
Post Reply
Cloudbridge
New Member
New Member
Posts: 5
Joined: Mon Jul 29, 2019 3:57 pm

Mon Jul 29, 2019 6:07 pm

- Fuel supply type (LP), size of pipe 1/2" and length of gas run: 700 ft
- Model and Serial number of generator: MODEL 47440 SERIAL 3980578

- Do you have access to testing equipment such as a digital volt meter and fuel pressure gauge: YES
- How long has the problem been happening, during cold/warm weather? Started March, 2019
- What has the maintenance been like for the generator (a lot of problems are due to a lack of maintenance): Every 100 hrs: inspection & oil change.

- Problem you're having, what have you done so far to try and resolve the issue:
Generator has 1023 hours on it. Wasn't run for 13 years until I moved it down the hill to my property. Changed battery, oil and air filter, topped up coolant. Started up fine, October, 2018, ran well, inspected by Generac service electrician. Herz & voltage correct. Started up remotely when called by the inverter to charge batteries all winter, perhaps 10-15 times (100 hrs).

Problems noted at start-up in 2018:
1. rpms did not modulate based on demand. Engine seemed to be running very fast. Electrician said that was normal, however my former generator, same year, similar model but 15KW, idled the engine speed when no demand, so not sure why this one wouldn't.
2. Occasional loud clank at random times that sounds like it's coming from the rotor assembly. Happens when first started, then rarely.
3. Note: in previous installation this generator was attached to a transfer switch. At my place it's off-grid.

In March the gen would start up and run for a few minutes then turn off. Fault light comes on then goes off on its own after a few minutes. (Located in Sonoma County, CA)
Oil and coolant very low, head looked a little oily. Thought it might be overheating. Mechanic checked compression, coolant circulation, coolant and oil sensors. All ok. Exhaust smoke looks normal. Gen faults off before engine is hot. Red sensor light on VR was on during run in March when faulting began. Now red LED on VR does not come on, no measurable current at circuit breaker terminals.
PROBLEMS
1. 12v gen starter battery not charging. When gen running, measure 7.4v at alternator. Belt found to be loose in March 2019, but tight now. Alternator or battery voltage regulator bad?
2. No amps at circuit breaker.
3. At startup, gen runs normally without generating amps. Engine guns itself several times before shutting down.

Should I replace the VR? What tests would be useful? Is there a setting that may have been used for the prior transfer switch set-up that I should correct for this off-grid location?
Attachments
2019-05-31Faceplate.jpg
2019-05-31Faceplate.jpg (81.36 KiB) Viewed 270 times
Chris
Site Admin
Site Admin
Posts: 601
Joined: Sat Aug 04, 2018 8:46 pm
Location: Clawson, MI
Contact:

Mon Jul 29, 2019 8:04 pm

Alright, I'll try to address the different things you mention here:

1. The loud 'clank' you hear is most likely the start re-engaging the flywheel while the unit is running. These old gens used voltage coming from the stator to tell the PCB that the unit is running. What happens is that the engine actually starts and IS running, however the PCB doesn't know that and tries to 're-start' the engine while it's already running. Normally about 15 seconds into the initial run...

2. The unit not producing voltage could be a few things. Could be worn brushes/dirty slip rings, could be a bad AVR, could be a bad field boost circuit. All of which are fairly easy to fix on this unit but will require some troubleshooting and knowledge of the system.

3. These units do not 'idle down'. Generators will only make 60Hz and normal voltage at one RPM, in this case 3600. The unit will always have to run at 3600 RPM to make power. It might be surging because of the lack of voltage input from the stator and it trying to re-start (see #1)

4. 700' of 1/2' line is incredibly far. I'm assuming that is at high pressure and then there is a regulator at the generator to step down to 11" or so?

5. Was the unit properly configured for LP if it came from a natural gas installation?
Generac tech for over 12 years. I'm here to help!
"The only source of knowledge is experience" -Albert Einstein
Looking for Generac parts? Gentek Power offers the full line of Generac replacement parts! Shop Gentek Power Generac Parts
A list of my favorite Generator & Electrical Tools! https://www.amazon.com/shop/gentek_power
Cloudbridge
New Member
New Member
Posts: 5
Joined: Mon Jul 29, 2019 3:57 pm

Tue Jul 30, 2019 3:21 pm

Re Question
4. Propane regulator was installed by a competent plumber in 2005 and calibrated by the tech from the propane company, so I expect it's ok. It put 4800 hours on the previous generac 15kw generator. I didn't have it re-calibrated for the 20Kw model. Would they have different pressure needs?

5. The 20 Kw generator was at my neighbors and was always used with propane.

A Generac certified electrician will look at it today. I'll share your suggestions with him.

Thanks so much for your thoughts. I'll share our results.
Cloudbridge
New Member
New Member
Posts: 5
Joined: Mon Jul 29, 2019 3:57 pm

Tue Jul 30, 2019 7:30 pm

Circuit testing and bumping VR wire 4 with battery voltage from the fuse confirmed that the VR is bad. Also, no current coming from battery charging alternator so will get a new one. Looks like the rest of the system is in working order.
Cloudbridge
New Member
New Member
Posts: 5
Joined: Mon Jul 29, 2019 3:57 pm

Tue Jul 30, 2019 7:35 pm

Can you recommend a replacement battery alternator for this generator? Is it
GENERAC 0E9868A ALTERNATOR ?
Chris
Site Admin
Site Admin
Posts: 601
Joined: Sat Aug 04, 2018 8:46 pm
Location: Clawson, MI
Contact:

Tue Jul 30, 2019 9:03 pm

No, that is the wrong one. Did you place an order on the site a little while ago? If so, it needs to be changed to the correct one! The alternator on that unit may not be bad, it could be the small voltage regulator.
Generac tech for over 12 years. I'm here to help!
"The only source of knowledge is experience" -Albert Einstein
Looking for Generac parts? Gentek Power offers the full line of Generac replacement parts! Shop Gentek Power Generac Parts
A list of my favorite Generator & Electrical Tools! https://www.amazon.com/shop/gentek_power
Cloudbridge
New Member
New Member
Posts: 5
Joined: Mon Jul 29, 2019 3:57 pm

Wed Jul 31, 2019 7:52 pm

Re: It could be the voltage regulator instead of the alternator--
With the generator running, no voltage is found when probing the connector coming from the rotating alternator. That seemed conclusive to me so I ordered a new alternator. Of course, the regulator could be bad too. Since the generator can run without either, I'm concentrating on getting the AVR replaced. Once it and the new alternator are installed, we shall see what else may need work.

Thanks for the correction to alternator model. The one you suggested is much cheaper too. Will I need any parts from the old alternator in order to install it?
Chris
Site Admin
Site Admin
Posts: 601
Joined: Sat Aug 04, 2018 8:46 pm
Location: Clawson, MI
Contact:

Thu Aug 01, 2019 8:10 am

Should be a direct swap in. :cool:
Generac tech for over 12 years. I'm here to help!
"The only source of knowledge is experience" -Albert Einstein
Looking for Generac parts? Gentek Power offers the full line of Generac replacement parts! Shop Gentek Power Generac Parts
A list of my favorite Generator & Electrical Tools! https://www.amazon.com/shop/gentek_power
Post Reply