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7500 Onan Generator won't Start


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I have a 04 Camelot 38 ' PST (original owner) and the generator wouldn't start (fault code 3, needs service).  Gen has 347 hours on it.  I serviced the gen (oil change, oil, air and fuel filter). Before I serviced the gen it would not start (did not turn over).  The light on the switch both inside and outside flashed 3 times then repeated.  The service was due anyway.  It had been 6 or 7 weeks since I had started it and was going to exercise it.  It ran fine after we returned home from our summer trip.  I have a full tank of fuel, oil is just under the full mark and the coolant is full.  I'm not sure if any of the items (oil level, fuel level and coolant level) would stop the gen from just turning over.  I have checked the voltage at the rear of the gen and have 13.8VDC.  With the covers off I measure the same at the starter solenoid.  The 3 fuses (2 15amp and 1 25 amp) under the external start panel are good (checked with a meter not just a visual).  Chased the ground wire attached to the gen back to the frame and it is good (clean and tight). Not sure if there is a way to check the solenoid.  The old school way to start a car if the solenoid was bad was to take a screwdriver and short out 2 poles and it would start or at least turn the engine over. There are only 2 poles on the solenoid and they are positive and negative so that won't work.  Any suggestions to what I might try to get the darn thing to turn over and hopefully start would really be appreciated.

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1 hour ago, NAMVET77 said:

I have a 04 Camelot 38 ' PST (original owner) and the generator wouldn't start (fault code 3, needs service).  Gen has 347 hours on it.  I serviced the gen (oil change, oil, air and fuel filter). Before I serviced the gen it would not start (did not turn over).  The light on the switch both inside and outside flashed 3 times then repeated.  The service was due anyway.  It had been 6 or 7 weeks since I had started it and was going to exercise it.  It ran fine after we returned home from our summer trip.  I have a full tank of fuel, oil is just under the full mark and the coolant is full.  I'm not sure if any of the items (oil level, fuel level and coolant level) would stop the gen from just turning over.  I have checked the voltage at the rear of the gen and have 13.8VDC.  With the covers off I measure the same at the starter solenoid.  The 3 fuses (2 15amp and 1 25 amp) under the external start panel are good (checked with a meter not just a visual).  Chased the ground wire attached to the gen back to the frame and it is good (clean and tight). Not sure if there is a way to check the solenoid.  The old school way to start a car if the solenoid was bad was to take a screwdriver and short out 2 poles and it would start or at least turn the engine over. There are only 2 poles on the solenoid and they are positive and negative so that won't work.  Any suggestions to what I might try to get the darn thing to turn over and hopefully start would really be appreciated.

Yes…a service fault

Three blinks indicates a service fault. Press Stop once to cause the two-digit, second-level fault code to blink. (Pressing Stop again will stop the blinking.)
 
First up, yes….OLD #CHOOL is good…but you need to understand and read the manual and the troubleshooting guides and such before you start “using old school” on it.
 
Here is a video.  All the code means…..you gotta problem!….but you need to know the sub codes.
 
Next up…..read.  Be aware…..this is a different critter.  It is a NEGATIVE start circuit.  All the wiring from the various start switches inside the MH or from the AUTO GEN START circuit is based on completing a ground….so, the old auto trick might cause problems or damage.  
 
IF I UNDERSTAND…. You have voltage to the two “battery terminals” on the rear of the genny.  That is great…..but, you have NOT verified that there is enough “juice” or current to actually turn over the starter.  Good you pulled the panel.  Now. I had a similar issue.  I went OLD SCHOOL.  I KNEW my house batteries were in great shape.  NO START.  I bypassed the troubleshooting….  I put s pair of Jumper Cables on the rear terminals from my TOAD.  Started the TOAD UP.  Hit the front start switch. VAROOM…started instantly.  Now, did I have a code? Maybe.  But I decided to test the batteries.  It was NOT the house batteries.  I used a VOM….bingo….
 
The House Battery Ground was “partially open”.  As in, the battery ground cable looked GREAT on the ground stud behind the battery box. I did it NON Conventionally.  I checked the resistance from the House ground to a REAL Ground.  Hmmm…4 ohms?  Then did the chassis….ZERO Ohms. What was happening was that every time I opened or closed the battery tray (pulled in or out), I had different readings on the House….but a solid ZERO Ohms on the Chassis.  I finished my trip.  Loosened the House Ground stud nut….rotated the terminal and burnished or polished the mating surfaces.  That was in 2015….45K miles later…..no issue.
 
My advice….if you can jump off and it starts and runs great…..nothing inside is wrong.  So, I would start there. NOW, had I had a clamp on AMMETER and a helper, the correct way is to measure BOTH the Voltage and the Amperage.  In my case, I would have seen a big voltage drop and very low current….as in, the batteries looked weak…but In actuality, it was a high resistance open connection.  Same symptom as yours…started great…..then stopped one day.  The high resistance connection finally caught up with me….
 
If it doesn’t start with jumper cables….then follow the book and get the sub code and start to troubleshoot.  The manual is easy and clear,..
 

 
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Thanks Tom.  I'll try to jump start it to see what happens but first I'll have to get the better half to help while I read the voltage while she tries to start the gen.  The batteries are only 6 months old (4 Trojan batteries) and should be good but I'll have to check anyway.  I also have a clamp on meter and I'll have that on too.  She won't be happy cuz it hasn't been above 30 degrees for several days.  The MH is in a garage and the temp is around 40 inside.  I keep the MH plugged in all the time.  Just tryin to get the darn thing to work.  More to follow.

Don

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37 minutes ago, Dr4Film said:

Don, are you holding the start position of the switch (top) long enough in this cold weather? The colder it is outside the longer you may have to hold it down to get the engine to turn over.

Richard has a good point.  

BUT….if you are getting the dreaded “3 digit code”, then you have to do the next step.  Here is a link to the codes.

https://manuals.heartlandowners.org/manuals/Electrical/Generator/Onan 5500/Onan Troubleshooting Codes.pdf

BUT….if you read, it is “daunting”.  BUT, one of the codes is a LOW OR NO Battery fault.  Mine had that, as I explained.  My logic is simle first….put jumper cables ON,  it don’t crank…..then start reading and following the troubleshooting.  It CRANKS…. Clean all the terminals….that includes the front ground to the Chassis and the rear House (or Chassis).

BTW….this is common.  You MIGHT loosen the two rear terminals.  Rotate sideways a few times.  BE AWARE…..these are copper or bronze studs. If you torque them like steel, you will break one.  A very astute member who is an expert inadvertently did that….so be aware …

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Generator Update.  Thanks for all the inputs.  After reading all the comments I looked closer for the error codes.  After the 3 digit code I pushed the switch again and got a code 19 (governor issue).  Nothing very specific.  After looking into governor problems I took a resistance reding on the two wire lugs on the governor and the readings were within parameters. I had already cleaned all the terminal connections I could find on the generator and chassis.  After doing all this the generator now starts.  I let it run for about 10 minutes and everything was running good so I put a load on it.  It ran for 15 minutes and shut down.  Wasn't real happy about that.  After waiting a couple minutes I started it up again, waited a few minutes and loaded it up again with the same results.  I have the top, right side and rear panel off and I'm hoping that it wasn't getting proper cooling since everything was open.  There were no error codes.  I have the fan belt off and a couple hoses off so I can't do any more troubleshooting until I get the parts back so I can run it again.  Hopefully once it is all closed up it works as it should.  I have done a complete service on it.  

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4 hours ago, NAMVET77 said:

I have the top, right side and rear panel off and I'm hoping that it wasn't getting proper cooling since everything was open. 

Had a similar experience where I did some service on the generator, fired it up, ran a bit and then shut down.  Realized that with the cover off the fan air was not being forced through the radiator.  Put cover on and all was good.

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6 hours ago, NAMVET77 said:

Generator Update.  Thanks for all the inputs.  After reading all the comments I looked closer for the error codes.  After the 3 digit code I pushed the switch again and got a code 19 (governor issue).  Nothing very specific.  After looking into governor problems I took a resistance reding on the two wire lugs on the governor and the readings were within parameters. I had already cleaned all the terminal connections I could find on the generator and chassis.  After doing all this the generator now starts.  I let it run for about 10 minutes and everything was running good so I put a load on it.  It ran for 15 minutes and shut down.  Wasn't real happy about that.  After waiting a couple minutes I started it up again, waited a few minutes and loaded it up again with the same results.  I have the top, right side and rear panel off and I'm hoping that it wasn't getting proper cooling since everything was open.  There were no error codes.  I have the fan belt off and a couple hoses off so I can't do any more troubleshooting until I get the parts back so I can run it again.  Hopefully once it is all closed up it works as it should.  I have done a complete service on it.  

Assume your PM incudes the Thermostat and gasket and a new heat sensor.  That and the drive/fan belt was the list of parts most experienced owners always carried.

 

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No to the thermostat and gasket. I just replaced the sensor 2 years ago. Guess I need to get the part numbers for the thermostat and gasket. 

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  • 2 weeks later...

Just an update on my generator issue.  I have been waiting for a belt for a week.  Supposed to be here tomorrow.  As soon as it gets here I will install it and put the panels back on and run it .  The last time I ran it, it ran for 15 minutes and stopped.  Since I had the side, back and top panels off I'm thinking it got to hot with all the panels off (air not properly circulating).  At least is was starting.  That was the original problem, not starting.  Once they are all back on I'm hoping my issue with shutting down goes away.  At least it did start.  More to follow.

Don 

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  • Solution

First I want to thank everyone for your input. Now I know a little more than I did before working on the generator. I received the new belt today and installed it right away. Checked everything real close then started it up. It started right away. Let it run for 15 minutes then put a good load on it and ran the genny for a half hour. It ran flawlessly. No error codes. So on to the next project (rebuild the air valves). Thanks everyone. 
Don

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  • 3 months later...
Posted (edited)

This is an older post but a good place to start. 

My wife is on a trip to a dog show, she stopped in Lexington at the Horse Park and ran the generator all night, next morning headed out and shut the generator off cool enough for the dogs with just the dash air.  She then made it Normal IL and stayed at a campground that night with electric, next morning getting ready to leave was going to run the generator but it wouldn't start.  Just clicks.   She stopped and got fuel, only took 75 gallons so I doubt the generator ran out of fuel, I know that it kicks off at 28 gallons in tank so she had +45 gallons.   She is now in Bloomington IL at the dog show.  

Trying to figure out what's going on, she face timed with me and let me listen to the clicking.  I had her go ahead and start the coach engine and try again same thing.  Had her recover the fault codes.   Got 3 blinks, had her press the stop button again and got 3-6, general service fault.  

What is the procedure for recovering a second fault code???

Prior to the trip I did do an inspection, oil change, air filter change, and installed a new belt.    I did not do a fuel filter change, I did one last year so few hours on fuel filter and I figure since I have a FASS system the fuel would be pretty clean from the polishing affect.   I did check the battery connections on the rear bottom of the generator both inside and out, they were good.   Since doing the service I started the generator 5-6 times before my wife left on her trip. 

Any comments. 

I've tried to call a mobile RV repair facility, no answer, left message.    Does anyone have the contact info for repair service near Bloomington.  She is headed to another show in Dundee Michigan after this, may have to try there. 

 

Edited by jacwjames
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I don't know about your generator spec but our 12.5 spec A has a couple of fuses behind a small removable panel by the breaker. One of them (F1) is for starter solenoid power. Your onan service manual would show it if the same.

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2 hours ago, jacwjames said:

This is an older post but a good place to start. 

My wife is on a trip to a dog show, she stopped in Lexington at the Horse Park and ran the generator all night, next morning headed out and shut the generator off cool enough for the dogs with just the dash air.  She then made it Normal IL and stayed at a campground that night with electric, next morning getting ready to leave was going to run the generator but it wouldn't start.  Just clicks.   She stopped and got fuel, only took 75 gallons so I doubt the generator ran out of fuel, I know that it kicks off at 28 gallons in tank so she had +45 gallons.   She is now in Bloomington IL at the dog show.  

Trying to figure out what's going on, she face timed with me and let me listen to the clicking.  I had her go ahead and start the coach engine and try again same thing.  Had her recover the fault codes.   Got 3 blinks, had her press the stop button again and got 3-6, general service fault.  

What is the procedure for recovering a second fault code???

Prior to the trip I did do an inspection, oil change, air filter change, and installed a new belt.    I did not do a fuel filter change, I did one last year so few hours on fuel filter and I figure since I have a FASS system the fuel would be pretty clean from the polishing affect.   I did check the battery connections on the rear bottom of the generator both inside and out, they were good.   Since doing the service I started the generator 5-6 times before my wife left on her trip. 

Any comments. 

I've tried to call a mobile RV repair facility, no answer, left message.    Does anyone have the contact info for repair service near Bloomington.  She is headed to another show in Dundee Michigan after this, may have to try there. 

 

OK, so that three flash followed by six is a fuel supply issue. More than likely it's a plugged fuel filter or fuel line. Make sure to replace the filter and make sure you have good new fuel and fire it up
 

OK, that what a 3-6 code is

I can tell you that the ONAN is way more sensitive to filters and also fuel "debris" than the engine. Buddy had some questionable fuel. Changed engine filters. Took 2 changes of Genny to get back to normal

 

Double dosing with Starbrite StarTron Diesel additive is a quick fix to clean up the fuel

AMAZON has it

My PERSONAL experience, without the codes was bad grounds at the Battery Box. I got NO NOISE or clicking

The only way to isolate Battery is to put Jumper Cables on the rear studs and hook up to a vehicle

That worked and mine started easily.  Batteries were new Trojans. So found the corroded Ground and cleaned it  

that's all I can offer from a personal or hands on standpoint

 

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In my experience, with my generator,  code 36 would not stop it from cranking if that is the problem. 36 means the generator stopped without the controller telling it to do so and it doesn't know why. Typically a fuel problem but not always. If the starter solenoid clicks, the fuse I mentioned earlier would not be the problem.

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Posted (edited)

The generator didn't stop while running, she shut it down and now it won't start. 

I'll have her check the small fuse first, that's the simplest thing to start with.    If she can get the genny to turn over and it still doesn't start then we'll look at the filter. 

 

FWIW, I've had the FASS system on the coach of almost 3 years, continually polishing the fuel.   When I was having trouble with a CEL last year first thing I did was change filter, I dumped each filter out and there was minimal sediments.  I use both Biobor & Startron on a regular basis.   Not saying there might not be a fuel quality issue but I'd be surprised. 

Edited by jacwjames
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13 minutes ago, jacwjames said:

The generator didn't stop while running, she shut it down and now it won't start. 

I'll have her check the small fuse first, that's the simplest thing to start with.  

OK…past that.  Clicking means a start signal.  Then, past a fuse, then try to start with Jumper cables attached.  My Genny ran fine.  Pulled into CG….was at CG for 2 days.  The Power went south and my Surge Protector said LOW AC.  OK…hit it.  Nada.  Jumper cables….bingo…started.  I FiNALLY kept opening and closing the battery trays and found a high resistance circuit….but got them to close with minimum resistance.  Cranked fine for another 4K and 2 months on road.  Cleaned the grounds….that was 9 years ago,  Never ONCE failed to crank since then.  An intermittent high resistance connection is a buggar to chase down…

good luck…

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Thanks Tom,

My biggest obstacle right now is walking her through how to check/change the fuse, beyond that I'm guessing it going to take a shop or mobile mechanic. 

She is traveling with dogs and in hot weather they need to be kept cool, so it's kind of an emergency situation. 

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1 hour ago, jacwjames said:

Thanks Tom,

My biggest obstacle right now is walking her through how to check/change the fuse, beyond that I'm guessing it going to take a shop or mobile mechanic. 

She is traveling with dogs and in hot weather they need to be kept cool, so it's kind of an emergency situation. 

Fully understand….you gotta get it fixed….

Keep us posted….

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Checked all 3 fuses under the access cover above start switch.  All good

Yes, she's tried other start switches, what is strange is the start switch on generator the starter just clicks, witch on the dash it turns over but still doesn't start.

So onto trying to change the filter.   I had a spare filter in the spare parts storage container so that parts covered. 

She's just crawling under the rig now, she was muttering some choice words a minute ago, so I'll let you know how it goes🙂

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