Lazy Daze Owners' Group

Lazy Daze Forums => Lazy Daze Technical => Topic started by: Hazel on January 26, 2026, 08:54:08 pm

Title: Replaced the Fuel Pump and Filter on the Onan 4000 Generator
Post by: Hazel on January 26, 2026, 08:54:08 pm
Hi,

I replaced the Fuel Pump and Fuel Filter on the Onan 4000 Generator on "Hazel".  Before I did this the generator would start and run for a bit and then die.  But it was providing power to the coach while it was running.  However after I replaced the Pump and Filter it is not providing power to the coach.  Does anyone know what I might need to check.  All the breakers in the coach and the one on the generator are fine.

Thanks,

Marc
Title: Re: Replaced the Fuel Pump and Filter on the Onan 4000 Generator
Post by: rich on January 26, 2026, 09:16:43 pm
Did you disconnect any wires and forget to reconnect them? 

I would triple check the breaker on the generator, jut to be sure.  

Could also be the Automatic transfer switch (you should hear an audible click from behind the power center as it switches over).

The Lazy Daze Companion: Generators – Trouble Shooting (https://lazydazearticles.blogspot.com/2012/10/generators-trouble-shooting.html)

Rich
Title: Re: Replaced the Fuel Pump and Filter on the Onan 4000 Generator
Post by: Hazel on January 26, 2026, 09:36:14 pm
Rich,

Thank you!  I will check all those things again.  I have also printed the troubleshooting guide.

Marc

Did you disconnect any wires and forget to reconnect them? 

I would triple check the breaker on the generator, jut to be sure.  

Could also be the Automatic transfer switch (you should hear an audible click from behind the power center as it switches over).

The Lazy Daze Companion: Generators – Trouble Shooting (https://lazydazearticles.blogspot.com/2012/10/generators-trouble-shooting.html)

Rich

Title: Re: Replaced the Fuel Pump and Filter on the Onan 4000 Generator
Post by: rich on January 26, 2026, 10:06:37 pm
Glad to help.

If you tell us the year and model of the coach, the moderators will put it in the footer of your posts, and it will generally help people answer this kind of question.

Rich
Title: Re: Replaced the Fuel Pump and Filter on the Onan 4000 Generator
Post by: Steve on January 27, 2026, 01:03:01 am
If you unplugged the multi-wire cable from the bottom of the controller box when you moved it aside, double-check that the plug was firmly seated in the mating socket...

Steve
Title: Re: Replaced the Fuel Pump and Filter on the Onan 4000 Generator
Post by: Hazel on January 27, 2026, 02:31:15 pm
Glad to help.

If you tell us the year and model of the coach, the moderators will put it in the footer of your posts, and it will generally help people answer this kind of question.

Rich


The Coach is a 2006 23.5' Rear Bath.
Title: Re: Replaced the Fuel Pump and Filter on the Onan 4000 Generator
Post by: Hazel on January 27, 2026, 02:32:09 pm
If you unplugged the multi-wire cable from the bottom of the controller box when you moved it aside, double-check that the plug was firmly seated in the mating socket...

Steve

I unplugged and reconnected it with an audible "click".
Title: Re: Replaced the Fuel Pump and Filter on the Onan 4000 Generator
Post by: rich on January 27, 2026, 09:37:36 pm
I don't know if it will help you, but I've found this resource to be useful in the past:
https://www.flightsystems.com/pdf/onan-rv-troubleshooting-guide.pdf

You will probably have to get a multimeter and start tracing where (if anywhere) the power is present.  Start with the generator output and work upstream or downstream from there depending on what you find.

Rich