Onan 7000 generator might be what you’re looking for.

With the Onan 7000 generator, whether putting your RV to bed for a long winter’s nap or simply getting it ready for a prolonged siesta, it is necessary to know how to winterize a Recreational Vehicle alternator for a prolonged duration of rest.


Step One: Fuel Suggestions

The initial step is to make certain your fuel tank is full before letting it sit for anything longer than thirty days. A partly full fuel tank permits condensation to form inside the tank which not only includes water to the mix but can likewise result in rust forming and triggering all kinds of concerns. A lot of experienced RVers determine their storage/winterizing schedule and let the fuel tank get low before storage so they can fill it with the appropriate fresh fuel before storing it. This is specifically essential for diesel Recreational Vehicle owners. Onan 7000 generator recommends filling the tank with a winter season grade fuel as noted in their owner’s handbook if the temperature level is going to dip below freezing.

Diesel Generators

Use any of the following ASTM accredited fuels for your peaceful diesel:

ASTM-No.2- D (ambient temperature level greater than 23 ° F) (No. 2 Diesel). or ASTM-1-D( No. 1 Diesel). No.2-DLS( ambient temperature higher than 23 ° F). No.1-D (ambient temperature of less than 23 ° F). No.1-DLS( ambient temperature level less than 23 ° F)

. B5 Biodiesel (ambient temperature level greater than 50 ° F)

. Make sure the fuel selected for usage has a minimum Cetane variety of 45. No. 2-D or No.2-DLS diesel fuel gives the best economy and efficiency under most operating conditions. Usage No. 1 diesel fuel when ambient temperatures are listed below 32 ° F and during long periods of light engine load. Utilize low sulfur or ultra-low sulfur material fuel having a cloud point of at least 10 ° F listed below the most affordable expected fuel temperature level. Cloud point is the temperature at which wax crystals start to form in diesel fuel.

B20 Biodiesel.

Using B20 biodiesel needs the alternator to have an additional fuel/water separator. Long-term storage of biodiesel fuels can lead to oxidation and/or mold development. Consult your car manufacturer and your machine owner’s manual to see if this choice applies to your generator.

Gas fuel generators can utilize routine unleaded or an Ethanol Blend not to exceed 10% Ethanol. The secret is to utilize fresh gas, absolutely nothing older than thirty days which is why it’s a great idea to run the tank low before refilling before storage.

LP Generators.

It’s a great concept to use fresh gas and a complete tank for your RV, an LP alternator is not impacted by the fuel used for the drive train. Onan does have recommendations for the type of propane: Usage tidy, HD-5 grade liquid propane in a mix of at least 90% gas. Propane fuels aside from HD-5 can contain more than 2.5 percent butane which can lead to bad fuel vaporization and bad engine starting in outside temperatures listed below 32 ° F.

Step Two: Support The Fuel Supply.

Any fuel will deteriorate as it beings in an engine or fuel tank for some time, usually as fast as thirty days. Gas will start to varnish producing a gummy residue that clogs the carburetor, fuel filter, and fuel pump and impacts efficiency. Unlike engine performance or fuel economy, the octane level or grade of fuel has little effect on the time factor of this fuel wear and tear. Diesel fuel does not weaken and produce varnish-like fuel, nevertheless, it can suffer biological development (algae) and gel in cold weather which will also impact engine performance.

It is suggested to use a quality fuel preservative and stabilizer with either diesel or gas designs. There are several brand names on the market with most of the popular diesel stabilizers readily available at the significant truck stops. Onan recommends OnaFresh fuel preservative and stabilizer.

Bear in mind, as soon as fuel starts to weaken and varnish is present in the generator, a preservative and stabilizer will not restore the fuel. At this point, you will require to try a fuel system cleaner or take apart the alternator  elements and clean/remove the contaminants.

Step Three: Run The System.

The next action in how to winterize an RV alternator is to run the unit under load for a minimum of 30 minutes. The power cell owner’s manual recommends 30 minutes plus 2 minutes for each foot of fuel line to make sure the stabilizer makes its method through all the lines and engine parts. Other service documents recommend running for 1-2 hours. Running the system for 1 hour must suffice and make certain you have something on inside that will supply a load to the alternator like the roof air units or plugging in an appliance like an area heating system.


Step 4: Modification The Oil And Filter.

It’s important to use the maker’s original parts for oil filters and advised oil. These parts often have inferior products used for filtering, sealing, and longevity which could cause pricey failures.

Onan has combined their specific oil branded as OnaMax, nevertheless, they do permit other brands under guarantee as long as they satisfy the following specs:

Gasoline Engine Oil Quality.

Usage oil meeting any of the following API efficiency classifications: SJ, SL, or SM where SM is presently the greatest quality readily available. Try to find the “Energy Conserving” classification to optimize fuel economy.

Diesel Engine Oil Quality.

Usage oil meeting any of the following API performance categories: CF, CF-4, CG-4, CJ-4, ch-4, or ci-4 where CJ-4 is presently the greatest quality readily available. Making use of artificial oil is not advised during the warranty duration. The use of oil meeting API efficiency classification CF-4, CG-4, CH-4, or CI-4 while burning fuel with a sulfuric content higher than 0.5% or CJ-4, while burning fuel with a sulfuric content greater than 0.0015% is not suggested as oil service, is negatively affected.

Oil Viscosities.

Utilize the following chart to choose appropriate viscosity grades for the expected ambient temperature range.


NOTE: Multi-grade oils (such as SAE 15W-40) is recommended for year-round usage in Cummins liquid-cooled engines, or as a great all-season oil for air-cooled engines.

KEEP IN MIND: SAE-30 is the preferred summer season grade for optimal oil intake control in Cummins air-cooled engines.

Step Five: Gas Engine Fogging.

, if you own a gasoline-fueled RV generator it’s suggested to get rid of the stimulate plug and spray Onan’s OnaGard misting spray to lower rust and condensation in the cylinder.


Step 6: Inspect Connections.

Make certain all cable televisions, wires, and other connections are tight and safeguarded. You may need to tidy battery cable connections and lubricate linkage points.

Step 7: Disconnect The Battery.

It’s a good idea to detach the ground terminal to the alternator to get rid of any battery drain or unexpected rise back from your house system if the unit is plugged in for storage.

Onan also suggests running the alternator when a month for at least thirty minutes under 50% load to minimize the gas degeneration and varnish and keep the seals softened in the diesel and LP units. In some scenarios, this is not possible, so it’s important to take the necessary steps to clean, protect, and stabilize the fuel source to make certain your power cell performs well for many years to come.

Hey people,

Prior to this the ATS would not constantly fire, and I delayed inspecting things as the alterantor was not urgently required (and I did not understand any better:-\ ). Now I am trying to nurse it back to health. I have actually cleaned it up, altered the oil, filter, air filter, plugs.

It now runs perfectly however it’s not sending power. Measured output at the machine reveals 1.2 volts using an Inova 3300 multimeter set for V 200 (unless I’m reading it wrong).

I’ve inspected the breakers at the generator, absolutely nothing appears tripped in the coach – what’s next? I’ve checked out online about inspecting the brushes but I do not see anywhere to access them. Any concepts on what to check next?





1996 Winnebago Vectra Grand Tour

Marquis 7000

Rene T.

Forum Personnel.



Posts: 13763.

Every day is payday and every payday I have off.

Re: 7000 Marquis not outputting power.

” Reply # 1 on: May 22, 2015, 12:37:07 PM “.

I understand absolutely nothing about this generator but if you have a 110 volt receptacle on it, why can’t you simply plug a light or electric drill in it and attempt it.


Rene, Lucille & co-pilot Pal.

AKA Pep N Mem.

2011 Chevy Duramax 2500 HD 4X4.

2011 Montana High Nation 343RL.

From the Granite State of NH.

& Florida Snowbird in Lakeland FL.



Posts: 6552.

Re: 7000 Marquis not outputting power.

” Reply # 2 on: May 22, 2015, 12:48:10 PM “.

The reading/setting on that meter, 1.2 V could be 120 V if set on the wrong scale. Last Edit: May 22, 2015, 12:53:30 PM by Alfa38User “.



Montréal, Canada.

Snowbird, Naples Florida.

Alfa Gold 38 (2000) 5ver (parked!).

” Naturally I speak with myself, sometimes I need specialist encourage!!!”.



Posts: 84.

Onan 7000 generator Marquis not outputting power.

” Reply # 3 on: May 22, 2015, 04:20:46 PM “.

I expect I might wire up a receptacle to among the output circuits and test that. That was a worry – that the 1.2 was really 120 at the incorrect scale – which would then cause an issue with the ats. I’ll head to House Depot tomorrow.




1996 Winnebago Vectra Grand Tour.

Marquis 7000.

Lou Schneider.

Online forum Personnel.



Posts: 9298.

Re: 7000 Marquis not outputting power.

” Reply # 4 on: May 23, 2015, 02:39:56 AM “.

Here’s a link to an outstanding Generator Troubleshooting Guide put out by Flight Systems, a company that makes replacement voltage regulator and control panel (if you end up requiring one).

If you require one of those, they also make a nifty slip ring cleaning tool.

One big idea on the Onans – if they aren’t putting out A/C voltage the engine will stop as soon as you release the START switch. The control logic needs to see generator voltage and good oil pressure for the engine to stay following you release the switch.

The voltage sample is prior to the generator breaker( s) so make certain they’re completely on. Expand your search to the ATS input and see if there’s voltage there and if so, is the ATS working correctly?

Make certain your voltmeter is set to AC volts and not DC – otherwise you’ll get incorrect and probably really low readings on the output of the generator.

” Last Edit: May 23, 2015, 02:47:41 AM by Lou Schneider “.




Posts: 84.

Re: 7000 Marquis not outputting power.

” Reply # 5 on: June 03, 2015, 11:33:46 AM “.

So I ended up taking the generator into a store to be looked at. If it had been sitting for a while un-used (it had), the tech asked. He drew out a 12 volt battery and ‘triggered’ it by connecting the battery causes the generator pos/neg wires (just a quick connection) – the generator started putting out 125 volts.

He said something to the impact that often the generator requires a quick ‘shock’ from the battery to get it to output power and in some cases it’s all that’s needed. Had anyone else ever seen that?




1996 Winnebago Vectra Grand Tour.

Marquis 7000.



Posts: 6332.

Re: Onan 7000 generator Marquis not outputting power.

” Reply # 6 on: June 03, 2015, 12:58:49 PM “.

With the Onan 7000 generator, I also Had to do this to the generators of my old Harleys when battery had actually been disconnected. At least you found a sincere store that didn’t offer a song and dance about something being incorrect and charging an arm and leg to repair you up. Last Edit: June 03, 2015, 01:01:06 PM by kdbgoat “.


I know you think you understand what you think I stated,.

But I am uncertain you understand what you heard is not what I meant.

2012 Redwood 36RL.

2016 Leprechaun 319DS.



Posts: 84.

Re: Onan 7000 Marquis not outputting power.

” Reply # 7 on: June 03, 2015, 01:05:06 PM “.

Excellent idea -.

RKL Motors.

4 Rainbow Crescent.

Norris Arm, Newfoundland.

( 709) 653-2300.

Charged me $20; I provided him $40, really nice man.

I’ll be actually delighted if that’s all it is. Ran the generator for about an hour up until now today, no concerns.




1996 Winnebago Vectra Grand Trip.

Onan Marquis 7000.

Onan 5500 Generator is the best in the market.

The Onan 5500 generator quite possibly could be the best in the market.Today’s world lends to a more technologically-savvy Recreational Vehicle owner and it’s not unusual for the modern-day tourist to desire the use of electronics on their RV holiday. For over 80 years Cummins has been setting the standard for quiet, reputable and innovative Recreational Vehicle power.

The Cummins 5.5 HGJAB-1270 RV alternator Set Recreational Vehicle QG 5500 LP Lp unit is the quietest generator in it’s class and functions exceptionally low vibration levels. It’s simple to set up and the self-diagnostic capability streamlines repairing. The maker’s 3-year minimal service warranty ensures you’re covered for the digital voltage and the long haul policy offers a safeguard for stability as home appliance loads alter.

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The quietest machine in its class features very low vibration levels at 67 decibels. RV QG 5500 generators are perfect for Class A motorhomes (2 air conditioners), Class C motorhomes, and 5th wheels. Recreational Vehicle QG 6500 and 7000 generators are ideal for Class A motorhomes (2 air conditioners) and Class A diesel motorhomes.

Marquis Gold Recreational Vehicle Generators now have the RV QG designation. They are available in 5500 Watt (RV QG 5500) and 7000 Watt (Recreational Vehicle QG 7000) gas models along with 5500 Watt (RV QG 5500 LP) and 6500 Watt (Recreational Vehicle QG 6500 LP) LP fuel generators. A few of the outstanding functions of this system include:

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It has extremely low vibration levels

Provides an integrated style with an enclosed muffler for easy setup

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This heavy-duty alternator runs 2 Air conditioners with power to spare

Digital voltage regulators for stability as appliance loads change

Dry weight: 290 lbs.

Measurements: 33.6″ x 22.2″ x 16.7″ High


RV QG 55005.5HGJAB-901Gasoline

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An upgrade or brand-new setup may include Remote Start Panels, Wiring Harnesses, and Tailpipes.

ItemDescriptionDimensionsPart #Harness/ Part #

Elbow & Tailpipe KitTailpipe


22″ Long


26″ Long

155-3439 Elbow





Remote Start PanelCut-Out:

1-1/8″ x 2″

300-493610′ Harness/ 338-3489-01

30′ Harness/ 338-3489-02

Remote Start Panel w/Analog Hour MeterCut-Out:

3-5/8″ x 2-3/8″

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Comparable to AboveRemote Start Panel w/Digital Hour MeterCut-Out:

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028-0002225′ Harness/ 044-00026

40′ Harness/ 044-00041

How to Replace the Fuel Pump and Fuel Filter on an Design 5500 RV Generator

Updated on January 18, 2019

Don Bobbitt profile image

Don Bobbitt more

Don is a retired engineer and long-time motorhome owner who delights in helping readers deal with the progressively intricate technology of RVs.

Contact Author

RV Generators Require Maintenance

Having a working power alternator in your Recreational Vehicle is so hassle-free for the owner that a lot of motorhome owners, especially, can not picture not having one for their journeys.

Of course, a generator, being a mechanical device, needs maintenance and care at times. And all mechanical gadgets will eventually break down, even if they are maintained properly.

So every RV owner who has a power cell ought to be prepared to have certain things spoil.

A basic Model 5500 Recreational Vehicle gas-powered generator.

A basic Onan 5500 generator  What Happened When My Recreational Vehicle Generator Died

Recently, my power cell stopped operating on me. It had a little over 500 hours on the meter, but it had always been kept correctly.

It had been running fine up until it stopped running. I could crank it, however, it would not fire up at all.

I needed to repair this, obviously, so I did some troubleshooting. I thought it had a bad fuel pump given that this is a typical problem with generators, however, I had to do some investigation to verify my suspicion.

View of the fuel pump and fuel filter on an Onan 5500 Recreational Vehicle generator.

View of the fuel pump and fuel filter on an Onan 5500 Recreational Vehicle generator.|Source

Repairing My Recreational Vehicle Generator

To find out what was incorrect with my generator, I went through a comprehensive troubleshooting procedure and eventually validated that the fuel pump on my generator was bad.

Throughout my diagnostics, I removed the cover of the alternator and figured out, among other things, that:

There were no loose connections visible.

There were no leaking fluids.

The motor had oil in the tank.

The DC source of power was excellent.

The fuel filter was tidy.

The initial step in fixing almost anything is to get rid of the apparent things from the list of possible issues.

Discovering the Fuel Pump

And I discovered another thing: On my generator, an Onan design constructed for motorhomes, they didn’t put the fuel pump inside the power cell compartment.

Rather, for some unknown factor, they chose to mount the fuel pump and the fuel line filter onto the underside of the generator base plate.

I must keep in mind here that over the years, these alternator manufacturers can alter their styles various times.

They may make a code generator, like my 5500-watt design, and after that have a dozen or more setups of the basic alternator to fit many applications.

Where mine is set up for my motorhome, the very same core alternator unit might likewise be configured as a portable design on wheels, a home backup power source, a remotely-controlled model for remote website backup power, or any of dozens of other special applications.

In these specialty designs, peripheral parts like the fuel pump, fuel filter, carburetor, air filter, and oil drain and input, can take various forms, or, as is typically the case, be mounted in various positions.

The position of the fuel pump and fuel filter on my RV though indicated that to replace the fuel pump, or perhaps just to replace the fuel filter, you had to get under the RV and work while pushing your back. I didn’t like this, but it was what had to be done.

Buying the Fuel Pump and Fuel Filter

I decided to change both the fuel pump and the fuel filter, as individuals frequently do, since they are mounted near one another and are low-cost, and I wished to make sure that I replaced whatever was causing the problem.

Among the excellent things about having a smart device is that you constantly have a good cam on hand. Even before I looked at the power cell handbook, I crawled under my RV and took several images of the fuel pump and the fuel filter that showed the labels as well as how they were mounted.

Back home, I sat down with my particular part numbers and images and went shopping the web for the best deal on the parts I needed.

It ended up that Amazon provided me the best rate and I was able to secure free shipping within 5 days of positioning the order. When I lastly received my parts, it was time to install them and get my alterantor running again.

Setting Up the New Parts


Here is where I should discuss that when you work on a device like a gas-powered generator, there are certain safety treatments you need to follow.

I disconnected the 12-V DC to the generator, shut off the fuel lines, and I also followed the other maker requirements noted in the owner’s manual.

As soon as all of this was done, I was ready to perform the actual replacement.

View of the fuel cut-off valve on an Onan 5500 gas RV generator

View of the fuel cut-off valve on an Onan 5500 gas RV generator|Source

Tools Required

By looking at the photos I had taken, I was able to identify the tools I would need for this task:

Flat-blade screwdriver (for the hose clamps).

Crescent wrench (for taking apart the fuel pump and fuel filter from each other).

5/16 socket and wrench set (for the 2 bolts that held the fuel pump to the base plate).

1/4-inch size wood dowel (or another device, to plug the fuel line from the fuel tank).

A short piece of plumbing’s tape (to assure a great seal in between the fuel pump and the filter).

Knowing this ahead of time permitted me to take to my Recreational Vehicle just the tools I would need, not a huge tool kit full of tools.

Fuel Pump and Fuel Filter Replacement Treatment.

Considering that in my case the fuel pump and the fuel filter were on the underside of the generator, I saw and inspected that there were only 2 things I had to detach on the upper side of the generator:

The 2 wires that supplied power to the fuel pump.

The actual output fuel line from the fuel pump to the input of the fuel cut-off valve that is inline with the carburetor of the generator.

So, the first thing I did was disconnect these 2 wires and this fuel line.

Then I crawled under the RV, removed the fuel line from the fuel filter, and stuck a piece of the wood dowel into the pipe to avoid it from leaking onto the ground and me.

I then removed the 2 screws that held the fuel pump in a location with the socket wrench.

Thoroughly, I pulled down the 2 wires and the fuel line with the fuel pump-fuel filter mix connected, and with this assembly in hand, crawled out from under the RV.

I link to 50 amp coast power without any issues operating all appliances including 2 a/c units. When I operate the Onan alternator only the forward a/c runs. When the rear a/c is turned on one of 2 things take place, the alternator shuts down or the alternator breaker snaps to off. No house breakers have ever shut off when utilizing the generator nor when plugged in. In this 2002 Georgie Boy, the electrical plug is either plugged into shore power or plugged into the generator. I am looking at six feet of wiring, the alternator to plug. I have physically eliminated the plug and junction box from the power cell and found nothing disconnected, absolutely nothing burnt, nothing shorted. Do any of you have a clue what may be occurring? Such as a common Onan 5500 alternator problem that may trigger an internal short?





1132 posts

Area: Beautiful Southern Wisconsin

I travel Part-time.

Report post.

Posted July 10.

Were you ever able to run both a/c systems on the generator, or has it constantly had this problem?





9497 posts.

Location: Galveston & Burnet, TX.

I take a trip: With pets.

Report post.

Published July 11.

With both Air Conditioner’s off, switch on the generator, then the bedroom Air Conditioning … the number of amps does it pluck spike when the compressor starts? Turn it off & do the very same with the front. Also, are both Air Conditioner systems the same size and what size are they?





3759 posts.

Place: Where ever the wheels stop?

Report post.

Published July 11.

On 7/10/2019 at 5:30 PM, elibedarn said:

When the rear a/c is changed on one of 2 things take place, the machine shuts down or the alternator breaker snaps to off. In this 2002 Georgie Young boy the electrical plug is either plugged into coast power or plugged into the generator. I have physically gotten rid of the plug and junction box from the machine and discovered absolutely nothing detached, nothing scorched, nothing short.

As recommended in the reply to your question.

Start each roofing A/C and note the Present requirement of the back and the front units. When the machine is running.

You might want to make sure that all the electrical connections are tight at the generator, transfer switch, and a/c breaker panels.

I see that your coach is wired for 50 amp coast power. You require to keep in mind that when running the alternator you have just a bit more than 50 amps of current supplied from the generator.

Link to the information covering the Onan 5500 series and the different setups for LP and Fuel.







287 posts.

Place: Central Frontenac Township, Ontario.

I travel Part-time.

Report post.

Posted July 11.

Rich, I think that the Onan 5500 generator in question just puts out a max of 45.8 amps at 120 volts. Even less capability.

a-1425. pdf.

290.35 kB · 6 downloads.





6 posts.

Report post.

Published July 11.

Is it heavy gauge, rated for more than 50 amps? Attempt to confirm all ground connections are tidy and tight in the coach and the Onan.


kay smith.

kay smith.


2795 posts.

Place: Hueytown, Al

. I take a trip: With animals.

Report post.

Posted July 11.

As specified above, you may be pulling too much load for one of the breakers and or the alternator itself. There is no comparison of this machine to 50 amp shore power.