Small Engine

Small Engine Troubleshooting Problems? Ask a Mechanic Now.

Ask an Expert,
Get an Answer ASAP!

I have a 1993 Pace Arrow with an Onan Marquis 7000 generator…

Customer Question
I have a 1993 Pace...
I have a 1993 Pace Arrow with an Onan Marquis 7000 generator with a 7NHMFA26106D model number. A year ago the generator would produce low voltage unless I hit a bump going down the road. Then it would kick in and work great. This year it will not produce more than 60 volts at all. I already replaced the voltage regulator and there was no change. What do I do next in order to get it working. The generator runs fine and starts right up.
Submitted: 8 years ago.Category: Small Engine
Show More
Show Less
Ask Your Own Small Engine Question
Answered in 46 minutes by:
6/28/2010
Technician: Hank F., Technician replied 8 years ago
Hank F.
Hank F., Technician
Category: Small Engine
Satisfied Customers: 15,978
Experience: Certified on Onan and Generac generators
Verified

Hello,

It sounds like you may have bad brushes or dirty slip rings.

 

Remove the air cleaner. Directly behind the air cleaner is the end bell of the generator. In the middle of the end bell is a rectangular plastic cover. Use a flat tip screwdriver to pry it out and expose the brush block.

 

In the center of the brush block are 2 round holes with a single bare wire coming out of them. These are the brush leads. Use a small diameter probe to stick down in these holes until it hits the brush. Mark the probe where it is flush with the brush block. Remove the probe and measure from the mark to the tip of the probe. If this measures 1" or more, the brushes are worn and must be replaced.

 

Leaving all wires hooked up, remove the 2 screws securing the brush block by turning each screw about 4 turns at a time. The brush block must come out straight, as it is made of ceramic and is very fragile. Be very careful to not drop the screws. It can be harder to get them out than to get a lollipop from a 2 year old. Use the wires to hold the brush block and guide it out.

 

Examine the brushes. They should not have any chips or cracks and should be worn in a smooth arc pattern. They should slide freely in the slots in the brush block. Clean the brush block with electrical contact cleaner.

 

I realize that you have already cleaned the slip rings, but we need to ohm them out to check for the proper resistance. They should read about 20-30 ohms.

 

Reassemble the set and see how it runs. If this did not help, please let me know and we will dig deeper.

 

Ask Your Own Small Engine Question
Technician: Hank F., Technician replied 8 years ago

Were you able to do these checks yet?

 

Ask Your Own Small Engine Question
Customer reply replied 8 years ago

I have not had time to check these yet. I will get to it by the end of the weekend. Thanks for your help.

 

 

Customer reply replied 8 years ago

okay, I just went ahead and picked up a new set of brushes and installed them. I then tried and there was no change. It is still not working. What should I try next?

 

Technician: Hank F., Technician replied 8 years ago

Check the slip rings and clean if necessary.

 

What is the ohm reading on them?

 

Ask Your Own Small Engine Question
Customer reply replied 8 years ago
You exactly should I check the ohm of the slip rings. I went through the brushes and I only get about 6 ohms.
Technician: Hank F., Technician replied 8 years ago

If you are only getting 6 ohms on the brushes, this would indicate a short in the windings of the rotor.

Low resistance equals low voltage output.

 

Unfortunately, the time has come to disassemble the set, pull the rotor, and inspect it for damage.

If there is physical damage, you are going to need to replace it.

 

Ask Your Own Small Engine Question
Customer reply replied 8 years ago
I was out messing with the generator again tonight an noticed that the fan on the back air condtioner would run but high speed was more like slow speed while the generator was running. I then tried to kick in the AC and it would pull the generator down but there was not enough juice to make it go. It leads me to ask this question, If the windings were bad wouldn't that mean there would be no voltage at all intead of just low voltage. I just want to make sure before I pull the thing out to repair it.
Technician: Hank F., Technician replied 8 years ago

No, it can still produce voltage.

The windings in the rotor will be shorted together, but not necessarily to ground.

A short to ground will cause the set to not produce electricity.

 

There is one other test you can do, but would require the use of a frequency meter.

Do you have one?

 

Ask Your Own Small Engine Question
Customer reply replied 7 years ago

Ok, sorry it has taken me so long to get back you. I moved, my email changed and I needed to get things checked out. I bought a manual for the thing and checked out the windings. I also took them out to be sure and had a rewinding shop look at them and they checked out fine both times so i put it back together and same thing.

 

Could the problem be with the rectifier?

Technician: Hank F., Technician replied 7 years ago

I am sorry about not replying last night - we have been working lots of over time at work, and I did not get home until well after midnight.

 

I am not going to be so naive as to say that the rectifier will not cause this - I have seen some pretty strange things happen - but a bad rectifier will normally either cause the fuse to blow or windings in the stator to melt.

Your set should not have a rectifier in it. Onan had a bad problem with the rectifier in a couple of sets, including this one, shorting out and melting stators. The rectifier is supposed to be removed from the set. The rectifier is not needed.

Here is how to remove it. This is assuming you have the internal rectifier - a small square block, about 1-1/4" square with 4 connectors, one in each corner, and is mounted inside the control box on the back wall.

If you have the external rectifier - an aluminum device a bit smaller than a pack of cigarettes with 3 terminals, mounted to the back of the set above the starter, this will not be necessary.

- Disconnect all leads from the rectifier.

- 2 of the leads are marked 'AC'. Cut the connectors off these 2 leads, and cover the leads with heat shrink tubing, or as an alternative, with a wire nut and electrical tape.

- Secure these leads so they can not come in contact with any ground source.

- One lead is marked CR10+ K1B+. The other end of this lead is connected to the starter solenoid. Simply remove this lead completely.

- The last lead is marked CR10- R6, and goes to a resistor mounted to the back of the set. Since you have the set out, remove this lead completely. An alternative is to cut the connectors of both ends of the lead and tape the ends.

- Remove the resistor.

- Remove the other lead from the resistor and discard it.

 

What exact readings did you get on all windings of the generator when you tested it?

Is your meter analog or digital?

Is is capable of measuring frequency?

 

Ask Your Own Small Engine Question
Customer reply replied 7 years ago
I am not sure because I had my dads shop check them out with the manual. Then I had an electical rewind shop take a look at them and both said they are not the problem.
Technician: Hank F., Technician replied 7 years ago

Remove the rectifier as described above, and let me know what happens.

 

Ask Your Own Small Engine Question
Was this answer helpful?

How JustAnswer works

step-image
Describe your issueThe assistant will guide you
step-image
Chat 1:1 with a technicianLicensed Experts are available 24/7
step-image
100% satisfaction guaranteeGet all the answers you need
Ask Hank F. Your Own Question
Hank F.
Hank F.
Hank F., Technician
Category: Small Engine
Satisfied Customers: 15,978
15,978 Satisfied Customers
Experience: Certified on Onan and Generac generators

Hank F. is online now

A new question is answered every 9 seconds

How JustAnswer works:

  • Ask an ExpertExperts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional AnswerVia email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction GuaranteeRate the answer you receive.

JustAnswer in the News:

Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.

What Customers are Saying:

You did one super job of explaining to me everything there is to know about this fridge. I'm looking forward to asking you questions in the future.

JimmyBagley, IA

Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help.

Mary C.Freshfield, Liverpool, UK

This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!!

AlexLos Angeles, CA

Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult.

GPHesperia, CA

I couldn't be more satisfied! This is the site I will always come to when I need a second opinion.

JustinKernersville, NC

Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around.

EstherWoodstock, NY

Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know.

RobinElkton, Maryland

< Previous | Next >

Meet the Experts:

Curtis B.

Curtis B.

Technician

15,517 satisfied customers

have worked on and around most engine models for 35 yrs./Polaris ATV expert

Rick

Rick

Factory Authorized Trainer

4,218 satisfied customers

Outdoor Power Equipment technical trainer since 1990, covering eight states.

Jon K.

Jon K.

Small Engine Diagnostic Expert

2,995 satisfied customers

Gold certified Stihl tech, Service Manager for a rental/repair shop.Certified in most small engines

James W

James W

Small Engine Troubleshooting Expert

2,986 satisfied customers

7 years as Mechanic & Parts Manager for Brother who has Owned Lawn & Garden Repair shop for 35 years

Vince O.

Vince O.

Small Engine Technician

2,927 satisfied customers

Over 30 years experience repairing lawn and garden equipment. Chainsaws, mowers,blowers and trimmers

Wayne

Wayne

Engine Rebuilder

2,041 satisfied customers

many years on egine rebuilding, lawn mower,roto tiller,Truck,and small engines

RUSS

RUSS

SERVICE TECHNICIAN

1,723 satisfied customers

28 YEAR SERVICE TECHNICIAN

< Previous | Next >

Related Small Engine Questions
I have an Onan Marquis 7000 generator, and carb is bad. I
I have an Onan Marquis 7000 generator, and carb is bad. I can't find a replacement anywhere. Is there an alternative that would work? … read more
Curtis B.
Curtis B.
Technician
Associate Degree
15,517 satisfied customers
How's its going from Arizona I have a Onan marquis gold 5500
How's its going my names Quentin from Arizona I have a Onan marquis gold 5500 an it was running fine on my last camping trip two weeks ago went outside today to run the generator why I cleaned the tra… read more
Hank F.
Hank F.
Technician
High School or GED
15,978 satisfied customers
I bought a 1995 Fleetwood Motorhome last month that came
Hello, I bought a 1995 Fleetwood Motorhome last month that came with an Onan Marquis 7000 Model number 7NHMFA26106D. The generator has been difficult to start form the beginning from a weak starter to hard starts without firing and once it does fire would die as soon as I let off of the start switch either form inisde the motorhome or at the generator itself. I found that if I hold down the star switch for several seconds after it initially seems to fire is the only way that the generator will continue running. I replaced the oil pressure sensor already but that did not solve the problem. … read more
Hank F.
Hank F.
Technician
High School or GED
15,978 satisfied customers
I am not getting 120 volts when my generator is running.
I am not getting 120 volts when my generator is running. … read more
Hank F.
Hank F.
Technician
High School or GED
15,978 satisfied customers
I have Onan Marquis 5.5BGM FA. It has been working fine, although
I have Onan Marquis 5.5BGM FA. It has been working fine, although I have to remove and clean the brushes holder every 500 hours or so, due to carbon buildup. This morning would barely start and produc… read more
Hank F.
Hank F.
Technician
High School or GED
15,978 satisfied customers
There. I have a onan 7000 marquis its putting out only
Hi there. I have a onan 7000 marquis its putting out only 60 volts ac any suggestions its idles, but if you give it throttle it dies..… read more
Hank F.
Hank F.
Technician
High School or GED
15,978 satisfied customers
I have onan marquis 7000 generator in a motor home Model
I have onan marquis 7000 generator in a motor home Model #7nhmfa26105d the generator will not start and run unless you hold down starter switch and play with the governor linkage going to carb. What c… read more
Hank F.
Hank F.
Technician
High School or GED
15,978 satisfied customers
I have a food truck and i am looking into buying a new
I have a food truck and i am looking into buying a new generator. My food truck can run easy off of 5500 watts right now. i have an onan marquis 7000 right now but the voltage regulator keeps blowing … read more
Hank F.
Hank F.
Technician
High School or GED
15,978 satisfied customers
hello hank, trying to troubleshoot onan marquis 5000 model
hello hank, trying to troubleshoot onan marquis 5000 model bgm. the gen will start and keep running but will not make power.have already replaced control board and cleaned slip rings and replaced spri… read more
Hank F.
Hank F.
Technician
High School or GED
15,978 satisfied customers
I have a Onan Marquis 7000 generator model 7NHMFA26106D it
I have a Onan Marquis 7000 generator model 7NHMFA26106D it has a 20amp and a 30amp breaker the 30amp popped several times so I replaced the breaker with a new one. The new one does not pop nor is ther… read more
Hank F.
Hank F.
Technician
High School or GED
15,978 satisfied customers
I have an onan marquis 5000 generator in my rv and it was running
I have an onan marquis 5000 generator in my rv and it was running great and then the ac unit stopped and now I only have 53 volts output ... I replaced the brushes and the voltage regulator and still … read more
Hank F.
Hank F.
Technician
High School or GED
15,978 satisfied customers
My 1992 Pace Arrow RV has an Onan Marquis 7000 Model 7NHMFA2606C
My 1992 Pace Arrow RV has an Onan Marquis 7000 Model 7NHMFA2606C SERIAL B920450470. It has a full tank of gasoline, with no load on generator, fuel pump runs during a stand-alone test, unit starts & r… read more
mx4life158
mx4life158
polaris tech
Vocational, Technical or Trade Scho
10 satisfied customers
onan marine generator 1988 mdk,8.0 I have to I have to exite
onan marine generator 1988 mdk,8.0 I have to I have to excite the generator each time to produce 110 volts… read more
Hank F.
Hank F.
Technician
High School or GED
15,978 satisfied customers
Hank, I got a new board from Dinosaur for the Onan 7000 generator.
Hank, I got a new board from Dinosaur for the Onan 7000 generator. As soon as you let off the start switch it will cut off. Any idea William Honbarrier… read more
Hank F.
Hank F.
Technician
High School or GED
15,978 satisfied customers
Hello I have an Onan 7000 watt generator in my 1994 Bounder
Hello: I have an Onan 7000 watt generator in my 1994 Bounder Motorhome that when I went to start it the four way retifier completely melted. I've tried several tests to find that the windings,brushes,… read more
Hank F.
Hank F.
Technician
High School or GED
15,978 satisfied customers
I have an Onan Marquis 7000 watt generator(HMF)1993 in a Bounder
I have an Onan Marquis 7000 watt generator(HMF)1993 in a Bounder motorhome that when it started it melted the four way rectifier. I ordered and replaced the rectifier but the generator won't produce e… read more
Hank F.
Hank F.
Technician
High School or GED
15,978 satisfied customers
Onan Marquis 5000 96 motor home. Do not use very often. Started
Onan Marquis 5000 '96 motor home. Do not use very often. Started 2-4 wks apart when stored. Did not use 3 mths when camping this winter. Did not start at end of trip. Serviced when I got home, fuel fi… read more
Carey (Turtle) Moore
Carey (Turtle) Moore
Supervisor Fleet Maintenance
Vocational, Technical or Trade Scho
175 satisfied customers
We have an Onan 7000 that was workign fine in the motor home
We have an Onan 7000 that was workign fine in the motor home until we plugged in an electric saw. Now none of the 110 works and we have traced everythign we can. the 12 volt works fine.… read more
Rick Armour
Rick Armour
Car Restorer
Vocational, Technical or Trade Scho
286 satisfied customers
Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Disclaimer: Information in questions, answers, and other posts on this site ("Posts") comes from individual users, not JustAnswer; JustAnswer is not responsible for Posts. Posts are for general information, are not intended to substitute for informed professional advice (medical, legal, veterinary, financial, etc.), or to establish a professional-client relationship. The site and services are provided "as is" with no warranty or representations by JustAnswer regarding the qualifications of Experts. To see what credentials have been verified by a third-party service, please click on the "Verified" symbol in some Experts' profiles. JustAnswer is not intended or designed for EMERGENCY questions which should be directed immediately by telephone or in-person to qualified professionals.

Show MoreShow Less

Ask Your Question

x