Generator repair - Generac Q-55G

[cm]

I completed a trouble shooting and repair on the Generac generator in a 1999 mororhome. It might help someone else who might have similar generator problems. The post is a little long but the details will help anyone having the same problem.

The generator would start and run but quit in a few minutes. It finally got to the point where it quit after only a couple of minutes. There are two switches on the generator. One is a start/stop switch and the other is a fuel pump primer switch. If I would push the fuel pump primer switch I could hear the fuel pump. The generator would then start but still die in a couple of minutes.

In using the starter switch on the generator it developed a soft feel when you pushed it. Eventually it would not crank the generator. But the inside starter switch would still crank the generator but then it would not start.

Also then the primer switch would not cause the fuel pump to make any noise. The fuel pump is located on the generator frame where the fuel line is attached. It has two wires. A hot lead and a ground line connected to the pump mounting bolt. I disconnected the hot lead and using a battery charger jumped the pump. The pump worked and the generator would start but still die after a few minutes.

I then started to trouble shoot the two switches. Each switch has three terminals connected by spade wiring terminals. By testing (use a multi-meter or test light) I found the hot lead. With a jumper wire I went from the hot terminal to the other terminals on both switches. Both the fuel pump and the starter (individually) would work as long as I had the jumper wire connected. Based on this I figured that both switches were bad.

Stand By Power in Commerce City, CO (metro Denver) carry Generac parts. They had one switch in stock and had to order the other. The switch came in when they said it would. From the owners manual the parts numbers are 87798 start/stop switch and 92113 fuel pump switch. The cost was $2.95 and $3.20.

Installed the new switches, used the fuel pump primer switch, and the generator started and runs fine.

Here are some hints to help anyone needed to do this repair.

As I mentioned you can trouble shoot each switch using a jumper wire. And you can test the fuel pump using a 12v battery charger.

Disconnect the coach batteries and the power cable to the generator before you go to pull the switches.

There is a large plastic cover over the switch area and the wiring so you need to remove it for access.

There is a 5 amp fuse located next to the switches. Make sure it is not blown. Also the panel that holds the switches is metal so if the batteries are not disconnected you might hit the metal as you remove the switch. The hot lead will blow this fuse. I tested this theory for you.

The switches have small clips on the ends to hold them in the openings. A small screwdriver can be used at the top and bottom to help remove the switches. The spade terminals on the switches are small so don’t just try and pull them off with plyers. It would possibly break the spade terminals. Use a small screwdriver to start lifting the spade terminals away from the switch. Then a larger screwdriver to keep pushing on the spade terminals. You are pushing lengthwise on the spade terminals so there is less chance of breaking it. There is very little slack in the wiring so having to replace the terminals could be hard. These don’t just slide on and off easily.

I hope this helps someone.

[JerryPeck]

roycet wrote:
Hi, I am in need of the diagnostic & repair manual for the Q55G and the above links do not work anymore, does anyone have access to this information?
Thanks in advance

I realize your inquiry is 2-1/2 years old, but I stumbled across it while looking for the same thing - the Diagnostic and Repair Manual.

The Diagnostic and Repair Manual is currently available here: http://www.bdub.net/manuals/Generac_IM-NP-Q.pdf

[supergroomer]

garym114 wrote:
Here is the Diagnostic and Repair manual for the Q55G if anyone needs it.
I used it to track down a bad starter solenoid.

The link you supplied asks for a Dealer log in. Do you have this as a pdf? I think I may have a bad selenoid. It goes click but no start.

Dave

[roycet]

Hi, I am in need of the diagnostic & repair manual for the Q55G and the above links do not work anymore, does anyone have access to this information?
Thanks in advance

[larrymorrell]

changed to mobile one synthic oil and replaced head and value this time. looks like I now have over 1000 hours since my last fix.

now that I am practice in working the models, I would like to find another one cheap someone has given up on. I would like to do some more experiments with units when not in RV.

only other issue I see with national RV install did not provide good way to isolate the air flow patterns. their design allowed cooling air to circulate and get back into generator.

I have been experimenting by adding instrumation all around the generator. I have figured out a few thing that will help you operate in hot weather when using the Genrac.

mybe my next project after RV oil pump replacement will be ducting air flow around generator to help it when driving and setting still.

[larrymorrell]

to all you generac users. how many hours have you on your units. I a 99 surf side and nq-55. my problem is sticking values. at about 520 hour stuck and woudl not run ofcourse. I removed unit and replaced the value with new one and set up spacing. run 230 more hours and happen again.

I have apart and going to put another head on it this time and clean up the new value stem.

any one else have simular problem. Also how many hours are you'll getting

[Denny___Jami]

garym114 wrote:
Here is the Diagnostic and Repair manual for the Q55G if anyone needs it.
I used it to track down a bad starter solenoid.

Thanks for the link, I copied to my documents for future use.

Denny

[ryanallie1]

big whitey wrote:

ryanallie1 wrote:
Hi All.

We also have a Generac 5.5G Generator. Thanks to cm & garym for posting the info. So far, our Generac Generator hasn't given us any problems at all. Nothing beats "Good Old Fashioned Maintence". A lot of people don't think much of a Generac Generator. But if you look at how many posts there are about Onan Generators that don't work, compaied to Generac Generators. I know there are a lot more Onan Generators out there than Generac Generators, but we really like our Generac Generator. This is the second Generac Generator we have owned, and both have been totally trouble free. Take care of your RV & Generaor, and your RV & Generaoter will take care of you. Thanks Again. Good Luck. Happy Travels. Dan & Jill

count yourself "LUCKY" on second thought very "LUCKY" i would prefer a used Honda/Yamaha than a new GENECRAP or the ONAN that folks used to swear by but now swear at.they are just flat out more dependable and quieter.i sincerely hope your luck holds out i wasn't so fortunate.

Hi All.

" Honda's ? " Check out our Signature. We wouldn't ever be without them. Good Luck. Happy Travcels. Dan & Jill

[garym114]

A good one to ignore.

[big_whitey]

ryanallie1 wrote:
Hi All.

We also have a Generac 5.5G Generator. Thanks to cm & garym for posting the info. So far, our Generac Generator hasn't given us any problems at all. Nothing beats "Good Old Fashioned Maintence". A lot of people don't think much of a Generac Generator. But if you look at how many posts there are about Onan Generators that don't work, compaied to Generac Generators. I know there are a lot more Onan Generators out there than Generac Generators, but we really like our Generac Generator. This is the second Generac Generator we have owned, and both have been totally trouble free. Take care of your RV & Generaor, and your RV & Generaoter will take care of you. Thanks Again. Good Luck. Happy Travels. Dan & Jill

count yourself "LUCKY" on second thought very "LUCKY" i would prefer a used Honda/Yamaha than a new GENECRAP or the ONAN that folks used to swear by but now swear at.they are just flat out more dependable and quieter.i sincerely hope your luck holds out i wasn't so fortunate.

[ryanallie1]

Hi All.

We also have a Generac 5.5G Generator. Thanks to cm & garym for posting the info. So far, our Generac Generator hasn't given us any problems at all. Nothing beats "Good Old Fashioned Maintence". A lot of people don't think much of a Generac Generator. But if you look at how many posts there are about Onan Generators that don't work, compaied to Generac Generators. I know there are a lot more Onan Generators out there than Generac Generators, but we really like our Generac Generator. This is the second Generac Generator we have owned, and both have been totally trouble free. Take care of your RV & Generaor, and your RV & Generaoter will take care of you. Thanks Again. Good Luck. Happy Travels. Dan & Jill

[garym114]

Here is the Diagnostic and Repair manual for the Q55G if anyone needs it.
I used it to track down a bad starter solenoid.