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Old 07-18-2020, 06:29 AM   #1
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THOR #14093
Generator only runs with engine on

I have 2015 Axis 24.1. Never had any issues with the Onan 4000 generator. Suddenly, about 2 weeks ago my generator started acting up. Right now I can't start the generator at all. The generator will start only with the engine running. As soon as I shut the engine off, the generator stalls out in about 5-10 min. My gas tank is more than 1/3rd full, all house batteries connections are good. I just replaced Onan's air filter and also will replace the spark plug and fuel filter. I have primed the gen several times with no success. Last time I checked the house batteries they were showing 12+ V.
I will double check the batteries conections again.
What other steps I need to take in order to correct this problem? Are the 5 year old deep cycle 12V batteries dying?

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Old 07-18-2020, 01:42 PM   #2
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The gen typically starts from coach (house) batteries, so check the charge and condition of your coach batteries (water levels if wet cell etc). If they are at rest (unloaded) and reading only 12.0 vdc they are almost fully discharged, so when you run the engine the alternator probablystarts charging the coach batteries enough to start the gen again. Sounds like your coach batteries need a full charge to 12.6 VDC approximately (if they are not damaged and will take the charge). If they won;t take a full charge or are damaged, it may be time to replace them.
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Old 07-18-2020, 02:33 PM   #3
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Quote:
Originally Posted by Rysiek View Post
I have 2015 Axis 24.1. Never had any issues with the Onan 4000 generator. Suddenly, about 2 weeks ago my generator started acting up. Right now I can't start the generator at all. The generator will start only with the engine running.
So does it start with the engine running or not? If it does, than you have a problem with supply voltage from the house batteries - either they are too dead to start the generator or the 100 amp DC breaker from the house batteries to the generator is tripped.


Quote:
Originally Posted by Rysiek View Post
As soon as I shut the engine off, the generator stalls out in about 5-10 min. My gas tank is more than 1/3rd full, all house batteries connections are good. I just replaced Onan's air filter and also will replace the spark plug and fuel filter. I have primed the gen several times with no success. Last time I checked the house batteries they were showing 12+ V.
I will double check the batteries conections again.
What other steps I need to take in order to correct this problem? Are the 5 year old deep cycle 12V batteries dying?
Sounds like a fuel starvation problem to me - again related to lack of good 12 VDC to the generator. In this case, the fuel pump. Once you remove the engines alternator voltage from the supply to the generator the fuel pump can't keep up and starves the generator.


Definitely a possibility
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Old 07-18-2020, 03:00 PM   #4
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If the generator continues to run for a few minutes after you shut down the engine, then it sounds like a electrical problem with the fuel system or the bird is supplying enough power to run generator with the engine running, when you shut engine off the impulse fuel pump is not running and the generator runs till it runs out of fuel,I know that most of these newer generators will not run if its own charging system isn't charging, I would look there and at the coach batteries as suggested.
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Old 07-18-2020, 03:35 PM   #5
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Thank you all for the help. I am going to check the voltage before and after I charge the house batteries today to see if they will hold the charge. I checked the water level and both batteries are good. Thnak you again.
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Old 07-19-2020, 01:47 AM   #6
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I need to add one more thing. Month ago I removed both house batteries in order to clean them but also to build the battery enclosure. I sprayed the battery terminals with the cleaner and than to protect against corrosion I applied another chemical. I wonder if applying all that stuff to the terminals would cause my charging issues?
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Old 07-19-2020, 07:33 AM   #7
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I just brought the coach home. Before I plugged it to shore power I have decided to check the voltage under different scenarios:
1. No shore power, switch flipped to NOT IN USE - both batteries read 12.3V

2. No shore power, switch flipped to IN USE, interior lights off - both batteries still read 12.3V

3. No shore power, switch flipped to IN USE, interior lights on - both batteries read 12.1 V

4. With the shore power, switch flipped to IN USE, interior lights on - both batteries read 12.7V
I left my coach plugged in to shore power overnight. Will see what is going to happen tomorrow. I will run exactly the same tests.
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Old 07-19-2020, 09:30 AM   #8
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Originally Posted by Rysiek View Post
I need to add one more thing. Month ago I removed both house batteries in order to clean them but also to build the battery enclosure. I sprayed the battery terminals with the cleaner and than to protect against corrosion I applied another chemical. I wonder if applying all that stuff to the terminals would cause my charging issues?
You didn't spray the post prior to installing the terminals?
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Old 07-19-2020, 06:57 PM   #9
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You didn't spray the post prior to installing the terminals?
I believe, I did. I guess I need to disconnect everything and clean the posts really well. What I was thinking
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Old 07-20-2020, 02:16 AM   #10
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I believe, I did. I guess I need to disconnect everything and clean the posts really well. What I was thinking
I have disconnected house batteries, cleaned the posts and cables very well, tightened up all connections, checked if the battery cells are wet, checked if the gen or the converter breaker were not tripped, checked the oil level and ... the generator would not start. The control panel shows that house batteries are fully charged (the coach was plugged in to shore power overnight). I have measured the voltage and the house batteries, unloaded were reading 12.7, with lights on 12.6.
Now, I started the coach's engine and in couple of minutes the generator was running perfectly. It started without any hesitation. Checked the voltage at this point to see 13.7V.
Than I stopped the coach's engine and the generator would stop as well in about 5 min after that.
No I am really confused an buffled. All of this sounds like fuel starvation. Right? Should I replace the fuel filter and fuel pump next? ⁹<
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Old 07-20-2020, 03:01 AM   #11
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Originally Posted by Rysiek View Post
I have disconnected house batteries, cleaned the posts and cables very well, tightened up all connections, checked if the battery cells are wet, checked if the gen or the converter breaker were not tripped, checked the oil level and ... the generator would not start. The control panel shows that house batteries are fully charged (the coach was plugged in to shore power overnight). I have measured the voltage and the house batteries, unloaded were reading 12.7, with lights on 12.6.
Now, I started the coach's engine and in couple of minutes the generator was running perfectly. It started without any hesitation. Checked the voltage at this point to see 13.7V.
Than I stopped the coach's engine and the generator would stop as well in about 5 min after that.
No I am really confused an buffled. All of this sounds like fuel starvation. Right? Should I replace the fuel filter and fuel pump next? ⁹<
When you say "will not start"; is it cranking over?
Did your house batteries ever reach 13.7 VDC with SP plugged in?
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Old 07-20-2020, 05:20 AM   #12
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When you say "will not start"; is it cranking over?
Did your house batteries ever reach 13.7 VDC with SP plugged in?
The generator is not cranking over at all. But as soon as I start the coach's engine it starts flawlessly abd right away

No, the batteries never reached 13.7 VDC. After being plugged in to SP for about16 hours the batteries were at 12.7 VDC.
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Old 07-20-2020, 01:40 PM   #13
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This is a head scratcher for sure. Sounds like your coach batteries are fully charged now at 12.7 vdc unloaded. In order for them to have charged, the converter connections to the coach batteries must be good (use/store is on; all breakers, use/store latch relay connections good). So why does the gen starter not kick on when you operate the gen start switch from coach batteries only (with engine not running)?


Letís try some additional things to see if we can get a bit more information: with use/store on:
1. Have you tried starting the gen with the switch right on the gen (with coach engine off)?
2. Start the coach engine and let it run for 5 minutes. What DC voltage reading do you get on the house batteries? It should be high 13ís or in the 14ís. It should be the same as what the chassis battery charging voltage is.

3. With engine off, operate and hold the emergency start relay switch near driver seat and then try to start the gen. Might need the DW to help unless you have very long arms.
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Old 07-20-2020, 07:44 PM   #14
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Originally Posted by javelin View Post
This is a head scratcher for sure. Sounds like your coach batteries are fully charged now at 12.7 vdc unloaded. In order for them to have charged, the converter connections to the coach batteries must be good (use/store is on; all breakers, use/store latch relay connections good). So why does the gen starter not kick on when you operate the gen start switch from coach batteries only (with engine not running)?


Letís try some additional things to see if we can get a bit more information: with use/store on:
1. Have you tried starting the gen with the switch right on the gen (with coach engine off)?
2. Start the coach engine and let it run for 5 minutes. What DC voltage reading do you get on the house batteries? It should be high 13ís or in the 14ís. It should be the same as what the chassis battery charging voltage is.

3. With engine off, operate and hold the emergency start relay switch near driver seat and then try to start the gen. Might need the DW to help unless you have very long arms.
It is a big time scratcher. Thank you for your help.
Here are some answers:
1. Yes, I have tried starting the gen right on gen. Primed the gen first as well.

2. After coach is running for few minutes the DC voltage reads 13.7 DC.

3. I have not tried this idea. Will do that today.
Altough, I could not start the gen by pressing emergency start from the dashboard
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Old 07-20-2020, 09:24 PM   #15
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Let us know what you figure out on this one.

My question is.... will your Generator run for 30 min or an hour ..... as long as your Ford engine is running? If so I would say its NOT a fuel problem.

I say its something with the batteries or battery cables or perhaps the battery isolator?
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Old 07-20-2020, 11:22 PM   #16
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Let us know what you figure out on this one.

My question is.... will your Generator run for 30 min or an hour ..... as long as your Ford engine is running? If so I would say its NOT a fuel problem.

I say its something with the batteries or battery cables or perhaps the battery isolator?
Yes, the gen will run without any issues as long as coach's engine is running. Couple of weeks ago I drove for 6 hours and the generator was on most of the time powering the AC. After arriving home, I turned everything off, waited few minutes and was able to start the generator without engine running! But that wae it. Another attempt has failed and everything went back to "new normal": engine not running - gen will not start.
I have no idea what other steps I should take. At this point I am tempted to replace the fuel filter anrfuel pump.
On the other hand I am suspecting that all of this is caused by some faulty
electrical components. Should I start shoping for a new battery?
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Old 07-20-2020, 11:39 PM   #17
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Can I play

Since the experts are stumped lets try a simpleton view Is it possible to put a charger directly on the house batteries to see if it starts? If it does, I would have the batteries load tested and replaced.

If it will not start when you manually try at the generator with engine off, it simply must not be getting enough juice despite the apparent voltage to turn over.
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Old 07-20-2020, 11:55 PM   #18
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Originally Posted by Rysiek View Post
The generator is not cranking over at all. But as soon as I start the coach's engine it starts flawlessly abd right away

No, the batteries never reached 13.7 VDC. After being plugged in to SP for about16 hours the batteries were at 12.7 VDC.
I assume you are measuring house batteries at the batteries location? If Your house batteries never went over 12.7 VDC when plugged into SP then either your converter is bad or you have a disconnect between the converter and the house batteries. That disconnect could be:

The large reverse polarity fuses on the fuse DC distribution panel.
The USE/STORE/Battery Disconnect latching relay OPEN.
The 50 Amp DC breaker tripped.

Quote:
Originally Posted by Rysiek View Post
It is a big time scratcher. Thank you for your help.
Here are some answers:
1. Yes, I have tried starting the gen right on gen. Primed the gen first as well.

2. After coach is running for few minutes the DC voltage reads 13.7 DC.
What DC voltage? What/Where are you measuring this?
Trace the main power positive cable from the house batteries, through the 100 Amp DC breaker (verifying it is not tripped) to the generator. Without the engine running; what is the voltage from this positive lead at the generator to ground?

If you have the same voltage as you have on the house batteries (12. VDC at best), continue to measure this voltage while someone pushes the generator start button. If it goes below 10 VDC you have bad batteries.
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Old 07-21-2020, 02:10 AM   #19
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Quote:
Originally Posted by Rysiek View Post
It is a big time scratcher. Thank you for your help.
Here are some answers:
1. Yes, I have tried starting the gen right on gen. Primed the gen first as well.

2. After coach is running for few minutes the DC voltage reads 13.7 DC.

3. I have not tried this idea. Will do that today.
Altough, I could not start the gen by pressing emergency start from the dashboard
I have tried the emergency startup and gen start switch. No success, gen is not starting or even cranking.
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Old 07-21-2020, 02:27 AM   #20
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Can I play

Since the experts are stumped lets try a simpleton view Is it possible to put a charger directly on the house batteries to see if it starts? If it does, I would have the batteries load tested and replaced.

If it will not start when you manually try at the generator with engine off, it simply must not be getting enough juice despite the apparent voltage to turn over.
Brought the coach from storage. Checked the batteries, 12.4 VDC. I thought I will give a try and start the gen. The generator started flawlessly, but...it died after 1 minute.

Then, I put a charger directly on the house batteries. The gen would not start from interior control panel or from the power switch on generator.
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