Good Sam Club Open Roads Forum: Onan 4000 generator cranks but won't start
Open Roads Forum Already a member? Login here.   If not, Register Today!  |  Help

Newest  |  Active  |  Popular  |  RVing FAQ Forum Rules  |  Forum Posting Help and Support  |  Contact  

Search:   Advanced Search

Search only in Tech Issues

Open Roads Forum  >  Tech Issues

 > Onan 4000 generator cranks but won't start

Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 4  
Next
SJ-Chris

San Jose, Ca

Senior Member

Joined: 09/24/2017

View Profile



Good Sam RV Club Member

Offline
Posted: 07/22/21 04:31pm Link  |  Quote  |  Print  |  Notify Moderator

Hi all,

I have a 2015 Cummins Onan RV QG 4000 generator. It has somewhere between 300-1000hrs (not sure, I've only owned it for about 2 years and it was a previous rental...might not be the original generator on this RV and I don't trust the hour meter coming from the rental company). About 1 year ago, I replaced the oil, air filter, and spark plug. Since then there has been 50-100 hours. Up until recently it has been working fine.

Recently, it won't start. It cranks and cranks very strong, but doesn't start.

To troubleshoot so far here is what I have done to no avail...
- I have a full tank of gas in the motorhome.
- The motorhome is level.
- Altitude adjustment set to 0 (I am near sea level).
- I checked the oil to make sure there wasn't too much (it is to the low end on the dipstick as most seem to recommend).
- I swapped in a good spark plug to make sure that wasn't the problem, and it didn't fix it.
- I checked the air filter and it seems fine (...even tried starting it without the air filter and it didn't start).
- I changed the fuel filter with a new one, primed it and tried starting it several times and that didn't fix the problem.
- I disconnected all the batteries (and my solar) per someone's suggestion to "reset" the generator. Hooked everything back up and it still didn't fix the problem.

It still cranks very strong...just doesn't start.

The only error code I could get from the lights was '4' (which is over-cranking). I don't think in all the testing that I did I ever let it crank for more than 10-20 seconds at a time.

I have reached the current extent of my generator knowledge! lol.... I'm hoping some of you can help me expand that knowledge with some more suggestions/recommendations.

One thing I've learned about owning an RV (...I actually have 3 now) is that it makes sense to try to learn to fix as much yourself as possible because RV mechanics are a)busy, b)expensive, and c)a hassle to drop off/pick up/etc. Plus, it's fun/satisfying when we can fix our own rigs and not be as dependent on others.

Thanks in advance!
Chris


San Jose, CA
Own two 2015 Thor Majestic 28a Class C RVs

gbopp

The Keystone State

Senior Member

Joined: 08/03/2008

View Profile


Online
Posted: 07/22/21 05:42pm Link  |  Quote  |  Print  |  Notify Moderator

Did you try spraying starter fluid into the intake while it's cranking? If it starts and runs a few seconds you probably have a fuel delivery problem.

SJ-Chris

San Jose, Ca

Senior Member

Joined: 09/24/2017

View Profile



Good Sam RV Club Member

Offline
Posted: 07/22/21 06:04pm Link  |  Quote  |  Print  |  Notify Moderator

gbopp wrote:

Did you try spraying starter fluid into the intake while it's cranking? If it starts and runs a few seconds you probably have a fuel delivery problem.


Thanks for the suggestion. Please help me understand how to implement your suggestion...

I assume the "intake" (carb?) is basically where the air filter is sitting, right? So would I remove the air filter and then spray starter fluid in there while cranking? The way the air filter housing is situated, I cannot see inside there so that will make it a bit challenging.

I guess something like this would work?
https://www.walmart.com/ip/STA-BIL-Starting-Fluid-22004/764691516?wmlspartner=wlpa&selectedSellerId=0&wl13=5766&adid=22222222420449455996&wmlspartner=wmtlabs&wl0=&wl1=g&wl2=c&wl3=501107745824&wl4=pla-293946777986&wl5=9032145&wl6=&wl7=&wl8=&wl9=pla&wl10=8175035&wl11=local&wl12=764691516&wl13=5766&veh=sem_LIA&gclid=CjwKCAjwruSHBhAtEiwA_qCppnLIDPa5g5DilwKFOS9sPvo0Jw7f8NKKMvDtZkLdTiH-NhoFiSPzRhoCEYsQAvD_BwE&gclsrc=aw.ds
Does it usually come with some sort of straw so that I could get it in closer to where the carb is (...the air filter housing is probably 4-5 inches deep).

I'll give it a shot. Thanks!

Any other suggestions?

-Chris

enblethen

Moses Lake, WA

Senior Member

Joined: 01/05/2005

View Profile






Posted: 07/22/21 06:13pm Link  |  Quote  |  Print  |  Notify Moderator

Did you check to see if spark is present at a plug? Possible bad coil.
Remove plug, connect plug wire, lay on metal surface and crank engine. Spark should be visible.


Bud
USAF Retired
Pace Arrow

2003 Chev Ice Road Tracker


SJ-Chris

San Jose, Ca

Senior Member

Joined: 09/24/2017

View Profile



Good Sam RV Club Member

Offline
Posted: 07/22/21 08:53pm Link  |  Quote  |  Print  |  Notify Moderator

Update:

I checked the spark plug. Took it out, then plugged it back into the wire connector and put it against the metal of the engine and when the engine cranked it produced rapid sparks. Yellow/white/orange in color (not blue). Is that significant?

Then I put the spark plug back in.

Then I took off the air filter and I sprayed some starter fluid into the carb area. At least that's what I tried to do. The spray can had a ~4" straw that helped me aim towards the carb opening but wasn't long enough for me to get it 100% into the carb, and because of the angle it was hard to see exactly what I was doing. I gave it 3-4 blast while manually holding the carb flap open. Then I tried starting it up. Didn't seem to make much of an impact and the engine just still cranked and cranked but didn't really seem to get any further. I tried spraying starter fluid 2-3 times more and still nothing. Because of some residual starter fluid spraying into the carb area (the housing that holds the air filter) at one point there was a tiny fire that started burning the excess fuel. I put it out within 5-10 seconds and it didn't look like it had any damage whatsoever. (I had a fire extinguisher next to me during all of this just in case!) Does this imply it is receiving the spark from the spark plug??

I'm not sure where to go from here. Any thoughts??

Thanks!
Chris

ROBERTSUNRUS

Salem, Oregon

Senior Member

Joined: 06/16/2010

View Profile



Good Sam RV Club Member

Offline
Posted: 07/22/21 11:04pm Link  |  Quote  |  Print  |  Notify Moderator

[emoticon] Hi, did you check the oil level?


"> Bob ">
2005 Airstream Safari 25-B
2000 Lincoln Navigator
2014 F-150 Ecoboost
Equal-i-zer
Yamaha 2400


SJ-Chris

San Jose, Ca

Senior Member

Joined: 09/24/2017

View Profile



Good Sam RV Club Member

Offline
Posted: 07/22/21 11:19pm Link  |  Quote  |  Print  |  Notify Moderator

ROBERTSUNRUS wrote:

[emoticon] Hi, did you check the oil level?


Yes, that was one of the first items I did. It was a little high. I sucked some out so that it is right around the bottom of the dipstick.

enblethen

Moses Lake, WA

Senior Member

Joined: 01/05/2005

View Profile






Posted: 07/23/21 06:44am Link  |  Quote  |  Print  |  Notify Moderator

When you removed the spark plug, was it wet, dry oily?

mgirardo

Brunswick, GA

Senior Member

Joined: 05/04/2007

View Profile


Offline
Posted: 07/23/21 07:09am Link  |  Quote  |  Print  |  Notify Moderator

Normally, you would spray the starter fluid while you starting the engine. Basically, start cranking, then spray it into the intake while it is cranking.

It definitely sounds like a fuel delivery issue. Less than a month after we bought our brand new Class C, with 3 hours on the generator, the fuel pump failed. Had it replaced under warranty. I don't know how much work it is to replace, but it isn't a very expensive part.

-Michael


Michael Girardo
2017 Jayco Jayflight Bungalow 40BHQS Destination Trailer
2009 Jayco Greyhawk 31FS Class C Motorhome (previously owned)
2006 Rockwood Roo 233 Hybrid Travel Trailer (previously owned)
1995 Jayco Eagle 12KB pop-up (previously owned)

Gjac

Milford, CT

Senior Member

Joined: 08/16/2006

View Profile



Good Sam RV Club Member

Offline
Posted: 07/23/21 07:24am Link  |  Quote  |  Print  |  Notify Moderator

Try disconnecting the fuel line to the carburetor and crank engine and see if any fuel is coming out. It could be a loose fuel pickup line or a bad fuel pump not allowing gas to get to the carburetor.

Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 4  
Next

Open Roads Forum  >  Tech Issues

 > Onan 4000 generator cranks but won't start
Search:   Advanced Search

Search only in Tech Issues


New posts No new posts
Closed, new posts Closed, no new posts
Moved, new posts Moved, no new posts

Adjust text size:




© 2021 CWI, Inc. © 2021 Good Sam Enterprises, LLC. All Rights Reserved.