7000 Onan gas generator help

John Duzac · 05-23-2022, 06:25 PM

Had issuers with my 7000 Onan gas generator at Ennis double. Weather was way too hot and I am wondering if the high temps was some of the issues. The generator seemed to be working fine and for some unknown reason the generator would just shut off. I was then able to restart it and everything would work fine for a while. Five minutes later the same thing, only thing when the generator would start, there would have no electricity to charge the batteries of anything else. I would turn the circuit breakers on the generator and everything seemed ok with the two breakers. This went on for quite some time. Does anyone had issues like this? Thanks and help will be appreciated.

SBillinson · 05-24-2022, 01:38 PM

I had a similar problem with a smaller Onan. The fuel pump failed. I mounted the replacement on the outside of the case to reduce the heat and have easy access if it fails again.

Sean Marconette · 05-24-2022, 01:57 PM

John,
There is a lot of information in the generator section. Below is a thread I started many years ago, and with Rich’s help my generator has been trouble free. If the electronic module overheats it will most certainly do as what you have described as it is also killing the fuel pump.

http://classracer.com/classforum/showthread.php?t=41189

Mike Pearson · 05-24-2022, 02:50 PM

I have gotten away from running my big gas generator during the day. I have a small 2200 inverter generator that I use to charge batteries and any power issues i need during the day. I have a handheld battery tire inflator that I use to keep the tires at the right pressure. I ran that little generator all day for 3 days last weekend and used less than 5 gallons of gas. At night I run the big gas gen when I need the AC.
Saves wear and tear on the big gen and saves money on the fuel too.

I like the older Onan generators that run at 1800 rpm. I have an old 6.5 that has points and condenser in my trailer. No electronics to give you grief. You can still find them around in good shape. Parts can still be found too. I have an 8KW quiet diesel in my toter. It is very fuel efficient and quiet. maintenance is really important on the generators.

dondon · 05-25-2022, 05:43 PM

a friend works at onan and he mentioned once that if the generator gets hot they shut off temporary. don't know if they all do or just some.

Nick_Siebert · 05-26-2022, 10:21 AM

On hot days, open the generator compartment door and prop the cover on the generator open to allow the hot air to vent out, I sell a lot of these generators in trailers and this is a common issue. They get hot and shut off.

John Duzac · 05-26-2022, 11:48 AM

Thank everyone for the information. Your comments has given me plenty of insight.

Joe Martens · 05-26-2022, 01:19 PM

Placing a fan on the generator should help. Not sure what weight oil you run but I run 15-40 in mine.

SGSST109E · 05-26-2022, 08:01 PM

I was schooled on the 7k generator by a factory tech. Opening the compartment door is fine do not open the cover on the generator; They are designed to pull air in from the bottom and out the side where the exhaust is. There should be a baffle between the intake and the exhaust often trailer manufactures ignore that step, So the cold air intake pulls in the exhaust air over heating the generator; Shoot the exhaust and the air intake with a gun and you will see. I made a baffle on mine curves around the exhaust pipe deflecting the air away from the intake

Rich Biebel · 05-26-2022, 08:19 PM

All Onan’s are designed to run with the service door in place.
The air flow is dependent on the door being on and tight
They do not have a high temp shutdown but will shutoff and it is from the control board and or the fuel lines, carb etc getting to hot
Many installs of these units ignore the airflow issues that make running hot worse
A fan directed at the compartment and to blow the hot exhaust away from the cool air intake area usually will help
The cooler air is drawn in along the bottom front area behind the oil filter and to the left.
With it running there is a very strong suction there and can pull a rag right out of your hand
I’ve seen birds nests up in there and bags or debris.
The lower they are to the ground the worse it can be
These units rely on air to cool and heat routinely causes cylinder head failures
The guides loosen up, valves and springs suffer from the overheating and the oil turns to sludge around the spring bases.
I do head replacements all the time. Finished one yesterday. Third one I’ve done in a month.
Anything you do to reduce the heat being drawn into the machine is a big plus.
I’ve seen one machine on a sign truck from Miami area with head failure from running to hot and it had under 1000hrs
Was mounted on the side of the truck very low to the ground and obviously was run in a hot area….Miami !
I work on them all the time.

My own 4000 watt Onan’s also would shut down if they got hot.
A big pit fan blowing directly at my trailer compartment mounted unit stopped the hot shutdowns
Do not run Onan’s with the service doors off ! Like I said it disrupts the designed air flow and will shorten the life of your machine. That goes for any Onan

05-23-2022, 06:25 PM	#1
John Duzac Member Join Date: May 2005 Location: Covington, La Posts: 310 Likes: 59 Liked 85 Times in 20 Posts	7000 Onan gas generator help Had issuers with my 7000 Onan gas generator at Ennis double. Weather was way too hot and I am wondering if the high temps was some of the issues. The generator seemed to be working fine and for some unknown reason the generator would just shut off. I was then able to restart it and everything would work fine for a while. Five minutes later the same thing, only thing when the generator would start, there would have no electricity to charge the batteries of anything else. I would turn the circuit breakers on the generator and everything seemed ok with the two breakers. This went on for quite some time. Does anyone had issues like this? Thanks and help will be appreciated. __________________ John Duzac D/S 4448 STK

05-24-2022, 01:38 PM	#2
SBillinson Junior Member Join Date: Jan 2004 Posts: 87 Likes: 39 Liked 166 Times in 47 Posts	Re: 7000 Onan gas generator help I had a similar problem with a smaller Onan. The fuel pump failed. I mounted the replacement on the outside of the case to reduce the heat and have easy access if it fails again. __________________ SS/BS 1921

05-24-2022, 01:57 PM	#3
Sean Marconette Senior Member Join Date: Mar 2006 Posts: 958 Likes: 617 Liked 165 Times in 60 Posts	Re: 7000 Onan gas generator help John, There is a lot of information in the generator section. Below is a thread I started many years ago, and with Rich’s help my generator has been trouble free. If the electronic module overheats it will most certainly do as what you have described as it is also killing the fuel pump. http://classracer.com/classforum/showthread.php?t=41189 __________________ Sean Marconette 84 Mustang 5060 SS/N

05-24-2022, 02:50 PM	#4
Mike Pearson VIP Member Join Date: Mar 2007 Posts: 2,318 Likes: 546 Liked 1,629 Times in 502 Posts	Re: 7000 Onan gas generator help I have gotten away from running my big gas generator during the day. I have a small 2200 inverter generator that I use to charge batteries and any power issues i need during the day. I have a handheld battery tire inflator that I use to keep the tires at the right pressure. I ran that little generator all day for 3 days last weekend and used less than 5 gallons of gas. At night I run the big gas gen when I need the AC. Saves wear and tear on the big gen and saves money on the fuel too. I like the older Onan generators that run at 1800 rpm. I have an old 6.5 that has points and condenser in my trailer. No electronics to give you grief. You can still find them around in good shape. Parts can still be found too. I have an 8KW quiet diesel in my toter. It is very fuel efficient and quiet. maintenance is really important on the generators. __________________ Mike Pearson 2485 SS

05-25-2022, 05:43 PM	#5
dondon Junior Member Join Date: Dec 2012 Posts: 26 Likes: 8 Liked 10 Times in 5 Posts	Re: 7000 Onan gas generator help a friend works at onan and he mentioned once that if the generator gets hot they shut off temporary. don't know if they all do or just some.

05-26-2022, 10:21 AM	#6
Nick_Siebert Junior Member Join Date: Jul 2007 Location: Wamego, KS Posts: 34 Likes: 45 Liked 26 Times in 7 Posts	Re: 7000 Onan gas generator help On hot days, open the generator compartment door and prop the cover on the generator open to allow the hot air to vent out, I sell a lot of these generators in trailers and this is a common issue. They get hot and shut off.

05-26-2022, 11:48 AM	#7
John Duzac Member Join Date: May 2005 Location: Covington, La Posts: 310 Likes: 59 Liked 85 Times in 20 Posts	Re: 7000 Onan gas generator help Thank everyone for the information. Your comments has given me plenty of insight. __________________ John Duzac D/S 4448 STK

05-26-2022, 01:19 PM	#8
Joe Martens Senior Member Join Date: Dec 2001 Location: North Olmsted, Ohio Posts: 772 Likes: 551 Liked 181 Times in 62 Posts	Re: 7000 Onan gas generator help Placing a fan on the generator should help. Not sure what weight oil you run but I run 15-40 in mine. __________________ Joe Martens A/Stock 3969

05-26-2022, 08:01 PM	#9
SGSST109E Member Join Date: Jun 2007 Location: NJ Posts: 342 Likes: 54 Liked 124 Times in 58 Posts	Re: 7000 Onan gas generator help I was schooled on the 7k generator by a factory tech. Opening the compartment door is fine do not open the cover on the generator; They are designed to pull air in from the bottom and out the side where the exhaust is. There should be a baffle between the intake and the exhaust often trailer manufactures ignore that step, So the cold air intake pulls in the exhaust air over heating the generator; Shoot the exhaust and the air intake with a gun and you will see. I made a baffle on mine curves around the exhaust pipe deflecting the air away from the intake

05-26-2022, 08:19 PM	#10
Rich Biebel VIP Member Join Date: Jun 2007 Location: Northern New Jersey suburbs Posts: 2,275 Likes: 25 Liked 510 Times in 200 Posts	Re: 7000 Onan gas generator help All Onan’s are designed to run with the service door in place. The air flow is dependent on the door being on and tight They do not have a high temp shutdown but will shutoff and it is from the control board and or the fuel lines, carb etc getting to hot Many installs of these units ignore the airflow issues that make running hot worse A fan directed at the compartment and to blow the hot exhaust away from the cool air intake area usually will help The cooler air is drawn in along the bottom front area behind the oil filter and to the left. With it running there is a very strong suction there and can pull a rag right out of your hand I’ve seen birds nests up in there and bags or debris. The lower they are to the ground the worse it can be These units rely on air to cool and heat routinely causes cylinder head failures The guides loosen up, valves and springs suffer from the overheating and the oil turns to sludge around the spring bases. I do head replacements all the time. Finished one yesterday. Third one I’ve done in a month. Anything you do to reduce the heat being drawn into the machine is a big plus. I’ve seen one machine on a sign truck from Miami area with head failure from running to hot and it had under 1000hrs Was mounted on the side of the truck very low to the ground and obviously was run in a hot area….Miami ! I work on them all the time. My own 4000 watt Onan’s also would shut down if they got hot. A big pit fan blowing directly at my trailer compartment mounted unit stopped the hot shutdowns Do not run Onan’s with the service doors off ! Like I said it disrupts the designed air flow and will shorten the life of your machine. That goes for any Onan __________________ Rich Biebel S/C 1479 Last edited by Rich Biebel; 05-26-2022 at 08:36 PM.