scdiver
Well-known member
- Joined
- Feb 28, 2014
- Posts
- 85
We have a 1995 Generac np66g in our mh that has needed a few repairs. In hopes of helping others I want to report the two problems and the fixes that I employed to keep this running.
The first problem sowed up on our 2015 trip to the Grand Canyon and Las Vegas. In the heat we drove with the genny running so we could run the air conditioners. I would shut the genny down at least every 24 hour to check the oil. After getting hot running in the desert the genny would not start, click or do anything when I hit ether start switch. As part of my diagnoses I took off the cover on the electronics, connected a jumper cable to the plus side of the coach batteries, the other side of the jumper cable to a large screw driver, then touched the screw driver to the starter side of the starter relay. This not only started the genny but caused the relay to loosen up and work correctly till the next hot time. A simple change of the relay fixed this problem.
The second problem was much harder and from some of the threads on the forums a common problem with these Generacs.
I would start the genny and it would start right up, but would produce no electricity. I was advised to hold the starter switch down a few seconds longer when starting and this seemed to help. Then it started to get worse. It seemed if the genny was cool, from rainy weather or just from cold weather, I had to run the genny for up to half an hour, stopping it then starting it about every ten minutes till it would produce electricity. This did not go over well when DW wanted to fix a meal. It was also a sign to me that something was going to fail permanently. I googled and found the service manual and the owners manual for this np66g Generac. I studied the service manual and since the temperature here in St. Louis was on the cold side and the genny would not produce power when cold I was able to follow the diagnostics and determined that the voltage regulator was probably at fault. Looking up the part number in the owners manual gave me a number of 74074. That number is not available any more but, there is a new number that is available. That number is 0830480SRV.
It was easy to install but there is a catch. To install this I took off the cover and turned off the circuit breakers. I then unbolted the old regulator and bolted the new one loosely with just the top bolt. Then since the wire connecting to this regulator are ether black or blue, yes all of them, I moved them one by one to the new regulator. I then finished up bolting it in the genny. Now came the catch. Leaving the breakers off I clipped a cheap volt-ohm meter to the input side of the breaker and the other line to ground. I then started the genny and got excited when the led on the regulator showing a high voltage output came on. The meter showed 89 volt output. I set the output by turning the pot next to the led to get 122 volts with no lode. I shut down the genny unclipped the meter and put the cover on the genny. Turned on the breakers and started the genny and got the proper voltage right away. This morning it was 38 degrees out and that genny started right up and produced electricity of the proper voltage so that I could run both air conditioners and a 1500 watt heater. I consider this genny fixed.
I know this is a long story but I hope it can help someone that is having these same problems with there Generac generator. Remember that new part number is 0830480SRV. I found several on Ebay and they are not cheap but I hope I have avoided having the genny fail me when I relly need it and my doing the repairs was a lot cheaper than having a shop do it. One last thing, the np52, np66, and np72 are basically the same gennys. I do not know about other Generac models.
The first problem sowed up on our 2015 trip to the Grand Canyon and Las Vegas. In the heat we drove with the genny running so we could run the air conditioners. I would shut the genny down at least every 24 hour to check the oil. After getting hot running in the desert the genny would not start, click or do anything when I hit ether start switch. As part of my diagnoses I took off the cover on the electronics, connected a jumper cable to the plus side of the coach batteries, the other side of the jumper cable to a large screw driver, then touched the screw driver to the starter side of the starter relay. This not only started the genny but caused the relay to loosen up and work correctly till the next hot time. A simple change of the relay fixed this problem.
The second problem was much harder and from some of the threads on the forums a common problem with these Generacs.
I would start the genny and it would start right up, but would produce no electricity. I was advised to hold the starter switch down a few seconds longer when starting and this seemed to help. Then it started to get worse. It seemed if the genny was cool, from rainy weather or just from cold weather, I had to run the genny for up to half an hour, stopping it then starting it about every ten minutes till it would produce electricity. This did not go over well when DW wanted to fix a meal. It was also a sign to me that something was going to fail permanently. I googled and found the service manual and the owners manual for this np66g Generac. I studied the service manual and since the temperature here in St. Louis was on the cold side and the genny would not produce power when cold I was able to follow the diagnostics and determined that the voltage regulator was probably at fault. Looking up the part number in the owners manual gave me a number of 74074. That number is not available any more but, there is a new number that is available. That number is 0830480SRV.
It was easy to install but there is a catch. To install this I took off the cover and turned off the circuit breakers. I then unbolted the old regulator and bolted the new one loosely with just the top bolt. Then since the wire connecting to this regulator are ether black or blue, yes all of them, I moved them one by one to the new regulator. I then finished up bolting it in the genny. Now came the catch. Leaving the breakers off I clipped a cheap volt-ohm meter to the input side of the breaker and the other line to ground. I then started the genny and got excited when the led on the regulator showing a high voltage output came on. The meter showed 89 volt output. I set the output by turning the pot next to the led to get 122 volts with no lode. I shut down the genny unclipped the meter and put the cover on the genny. Turned on the breakers and started the genny and got the proper voltage right away. This morning it was 38 degrees out and that genny started right up and produced electricity of the proper voltage so that I could run both air conditioners and a 1500 watt heater. I consider this genny fixed.
I know this is a long story but I hope it can help someone that is having these same problems with there Generac generator. Remember that new part number is 0830480SRV. I found several on Ebay and they are not cheap but I hope I have avoided having the genny fail me when I relly need it and my doing the repairs was a lot cheaper than having a shop do it. One last thing, the np52, np66, and np72 are basically the same gennys. I do not know about other Generac models.