Onan repair

ss3011 · 08-19-2012, 10:32 PM

I have the same problem with my Onan 4000 Microlite. I replaced the carburator about three years ago and that fixed it, but now it is back doing the same thing. It runs for five to ten minutes then shuts down and wont restart. I disconnected the fuel line, and when I crank it, plenty of fuel pumps out. I tried cleaning and blowing out all the passages of the carb, but still has the problem. I am thinking of buy another carb. If your generator gets fixed please post what they did to fix it. Thanks

Rich Biebel · 08-20-2012, 07:15 AM

Most later 4KY's have the coil mounted under the blower/flywheel.
The coil wire is part of the coil and it is a magneto type ignition.
The coil wire is at a very sharp angle as it routes to the spark plug.
The vibration of the engine and the bad angle of the wire often causes the wire to fail. It is a carbon core type wire and you lose spark as the unit gets hot......
Possibly your problem....

Fuel pumps are a piston design and even though you see fuel coming out cold.....it could still be your issue. If it was never changed and the unit has some hours on it.....it may be your problem....

The solinoid on the carbs fuel bowl energizes with the pump and allows fuel to flow. If has a ground wire and a B+. They don't fail often but do get stuck from a unit that sat with fuel in it....

joe176 · 08-20-2012, 11:13 AM

I had an issue with my RV Onan generator shutting off a few years ago .......Matt Schurman is the go to guy.....D1 super gas racer....brought the RV to his company in northern NJ ...( mind you I live on Long Island and RV repair places here are crooks) and he found it was a coolant sensor.....did a complete tune up on it which included removing this monster from the truck to get to the sensor for $700....was totally happy with Matt and his work....great guy to do business with.

Rich Biebel · 08-20-2012, 12:55 PM

Joe that was a difficult job as I recall....getting the generator out and back in was no bargain....

We have had others just as bad........

Front mounted diesels.....no slide and have to remove the front of the M-H to get the generator out....

Matt and I have worked together for 20 years now.....

Rich

joe176 · 08-20-2012, 09:55 PM

Rich I didn't know you worked with Matt......knew it had to be difficult considering the circumstances.....you "guys" did a great job !!!!!!!!!!!!!!!!

Rich Biebel · 08-21-2012, 09:50 AM

Joe I am the guy Matt says infected him with drag racing...

He usually says that after losing in the first round somewhere....LOL

ss3011 · 08-21-2012, 04:19 PM

That is interesting about the coil wire. I had pulled the spark plug out , then reattached the spark plug wire, and I cranked it over. Thought the spark was a bit weak, might be the problem . Can you change the coil without removing the generator from the motorhome ? Thanks for the tip !

08-19-2012, 10:32 PM	#1
ss3011 Senior Member Join Date: Feb 2002 Location: Southeast Michigan Posts: 909 Likes: 70 Liked 239 Times in 114 Posts	Re: Onan repair I have the same problem with my Onan 4000 Microlite. I replaced the carburator about three years ago and that fixed it, but now it is back doing the same thing. It runs for five to ten minutes then shuts down and wont restart. I disconnected the fuel line, and when I crank it, plenty of fuel pumps out. I tried cleaning and blowing out all the passages of the carb, but still has the problem. I am thinking of buy another carb. If your generator gets fixed please post what they did to fix it. Thanks

08-20-2012, 07:15 AM	#2
Rich Biebel VIP Member Join Date: Jun 2007 Location: Northern New Jersey suburbs Posts: 2,314 Likes: 25 Liked 544 Times in 213 Posts	Re: Onan repair Most later 4KY's have the coil mounted under the blower/flywheel. The coil wire is part of the coil and it is a magneto type ignition. The coil wire is at a very sharp angle as it routes to the spark plug. The vibration of the engine and the bad angle of the wire often causes the wire to fail. It is a carbon core type wire and you lose spark as the unit gets hot...... Possibly your problem.... Fuel pumps are a piston design and even though you see fuel coming out cold.....it could still be your issue. If it was never changed and the unit has some hours on it.....it may be your problem.... The solinoid on the carbs fuel bowl energizes with the pump and allows fuel to flow. If has a ground wire and a B+. They don't fail often but do get stuck from a unit that sat with fuel in it.... __________________ Rich Biebel S/C 1479 Stock 147R

08-20-2012, 11:13 AM	#3
joe176 Senior Member Join Date: Apr 2003 Location: NY Posts: 601 Likes: 36 Liked 41 Times in 9 Posts	Re: Onan repair I had an issue with my RV Onan generator shutting off a few years ago .......Matt Schurman is the go to guy.....D1 super gas racer....brought the RV to his company in northern NJ ...( mind you I live on Long Island and RV repair places here are crooks) and he found it was a coolant sensor.....did a complete tune up on it which included removing this monster from the truck to get to the sensor for $700....was totally happy with Matt and his work....great guy to do business with. __________________ Joe Franco SS176

08-20-2012, 12:55 PM	#4
Rich Biebel VIP Member Join Date: Jun 2007 Location: Northern New Jersey suburbs Posts: 2,314 Likes: 25 Liked 544 Times in 213 Posts	Re: Onan repair Joe that was a difficult job as I recall....getting the generator out and back in was no bargain.... We have had others just as bad........ Front mounted diesels.....no slide and have to remove the front of the M-H to get the generator out.... Matt and I have worked together for 20 years now..... Rich __________________ Rich Biebel S/C 1479 Stock 147R Last edited by Rich Biebel; 08-20-2012 at 02:03 PM.

08-20-2012, 09:55 PM	#5
joe176 Senior Member Join Date: Apr 2003 Location: NY Posts: 601 Likes: 36 Liked 41 Times in 9 Posts	Re: Onan repair Rich I didn't know you worked with Matt......knew it had to be difficult considering the circumstances.....you "guys" did a great job !!!!!!!!!!!!!!!! __________________ Joe Franco SS176

08-21-2012, 09:50 AM	#6
Rich Biebel VIP Member Join Date: Jun 2007 Location: Northern New Jersey suburbs Posts: 2,314 Likes: 25 Liked 544 Times in 213 Posts	Re: Onan repair Joe I am the guy Matt says infected him with drag racing... He usually says that after losing in the first round somewhere....LOL __________________ Rich Biebel S/C 1479 Stock 147R

08-21-2012, 04:19 PM	#7
ss3011 Senior Member Join Date: Feb 2002 Location: Southeast Michigan Posts: 909 Likes: 70 Liked 239 Times in 114 Posts	Re: Onan repair That is interesting about the coil wire. I had pulled the spark plug out , then reattached the spark plug wire, and I cranked it over. Thought the spark was a bit weak, might be the problem . Can you change the coil without removing the generator from the motorhome ? Thanks for the tip !