Onan generator issues

[Khaos13]

Hello All. My name is Dan and I live in Ft. Lauderdale. My neighbor and good friend just bought a 1994 26' Tioga Arrow and he needs help. So do I!

I've been a merchant mariner for most of my life; captain AND engineer. I've always said (until now) that I can fix anything. I worked on yachts for 30 years and in the GOM oil fields for the last 10. I've worked on just about every type of diesel made in the last 50+ years. EMD's, Alcos (locomotive engines) and the usual Cats, Detroits, etc.

The Onan generator on this RV is a challenge however and that's what brought me here. I've only been tinkering with it for the last few days and I already hate it! I look forward to talking with anyone who can shed some light on this frustrating piece of gear as well as other issues that I am sure will arise.

Thanks in advance for your help.

Cheers,
Dan

 

[Tom]

Hi Dan and welcome to The RV Forum. I suspect that your prior experience will be quite helpful to others here. A number of us are/were recreational boaters, but few are/were pros in the marine world.
What's the Onan issue you're having trouble with?

 

[Gizmo100]

Welcome to the RV Forum Dan

I'll let others help with the Generator.

 

[RVMommaTo6]

Hi Dan, welcome to the forum! My dad has a place in Ft Lauderdale, beautiful place to live!

 

[Khaos13]

Good morning Tom. Thanks for the warm welcome.

Our generator issues seem to be common problems for a lot of folks here. It runs for a minute or so then shuts down. I've done a lot of testing and believe the problem is DC power to the fuel pump and and fuel cutoff solenoid at  the carb. I removed the plunger from the fuel solenoid and got the engine to run but only for a minute or so. After shutdown, I'd open the bowl drain and no fuel came out. Ah haa... fuel pump! I disconnected the fuel line at the carb, ran it to a small bowl and hit the start switch. Plenty of fuel flow. I disconnected the hot wire to the fuel pump and added a jumper so I could connect it directly to battery power (at the starter solenoid) and started it up. Every time it started to die I'd touch the wire to battery power power for a few seconds and the engine would continue to run. While running, I put my meter on the original pump wire and no voltage. I did the same to the fuel cutoff solenoid and no voltage. (Strangely, leaving the fuel pump hot wired to battery made it run worse.) BTW, with the start button activated, the voltage at the original pump wire and fuel shut off solenoid is 11 VDC. With the start button released the voltage dropped to zero. I believe that some protection device is causing the problem. Perhaps it's hertz or voltage inconsistencies, oil level sensor etc. That's where I'm at now with troubleshooting. Today's mission is to isolate and bypass that protection so that the pump and cutoff solenoid are getting voltage.

Aren't you sorry you asked?  Have a great weekend!

P.S. I know this isn't the place to post all of this but you DID ask.  8)

 

[darsben]

You do not mention which ONAN you have but if it starts then stops it could be the low oil level safety. The safety will allow the engine to start and then shut it down
Another possibility is some ONAN's will shut down if there is no load on the Genny after 30 seconds

 

[Khaos13]

Hello. The generator is a 1994 Onan MicroLite 4000. Interesting news about load detection. There has been no load on this gen while testing. In fact, I?m not sure it is producing AC power at all. The darn thing is in such an awkward place to work on and I really don?t want to remove it. The ergonomics of this gen are terrible. I can?t see why the manufacturer was so concerned with keeping it small that they made it nearly impossible to service. A few more inches would make all the difference. For the measily 4 kw and all of the issues with it, I?d go with the Honda portable and solar panels.

BTW, I?m sure you?re aware of the biblical references to Onan. Working on this thing makes feel as the biblical Onan must have felt; a futile exercise.  ???

 

[phil-t]

Flight Systems
Has some very good troubleshooting guides.  They also sell parts and control boards.

Good luck with that genny.

 

[Khaos13]

Great tip Phil. Watched a video, read some tips. Knowledge is never too heavy a burden to carry. Have a great Memorial Day.

 

[NY_Dutch]

If the generator runs until you let go of the start switch, it could be the oil level switch or the voltage regulator. The generator will not continue to run if it doesn't detect power being generated. There does not need to be a load on it, just the correct voltage range, and the circuit breakers do not need to be on for the control board to sense the voltage.