Onan generator - runs 4-5 mins then quits

[vgorke]

just bought an RV - pardon the basic question..  I have a 7.5kw diesel Onan Genset.. in a Winnebago 40JD..  it runs for about 4 mins then seems to shut it's self down..  is this because there is no electric draw on it? is this a feature or an issue?

thanks
Newbie

 

[Ned]

When it shuts down, check the light in the start/stop switch.  It should be blinking a fault code.  If the first code is 1 or 3 blinks, there will be a second blink code.  Tell us what those are.  If you have the owner's manual for the Onan, this is all explained in there along with the code meanings.

 

[wileee]

This is an admission that I wasn't very smart when my generator would run for a few minutes, then quit.

I took it to Cummins/Onan, and they did a $450 repair, installing a new voltage regulator. 

The next month, it was doing the same thing.  Another $450 repair.  Last week, I took a different problem to them, which I had called them about in June.  They replaced the voltage regulator, AGAIN, and told me it was out of warranty, since it was past 90 days.

I think the only thing wrong with the generator, initially, was that the generator's fuel pickup in the vehicle's fuel tank was higher than I had thought.  When the gauge reads a little below 1/2, the tank is less than 1/4 full.  Since the generator's pickup is above the engine's pickup, it quits before it runs the tank dry and leaves you stranded.

Check your fuel level.  Fill the tank and try the generator again.  It would have saved me $900!

 

[Jeff]

If Cummins charged you 900 bucks for a voltage regulator when your gen was out of fuel I would be talking to management about a refund!

 

[afchap]

Most are supposedly set up so that the generator will not run when the fuel tank is below 1/4. ...but my generator has never stopped running due to fuel level, not even when the low fuel warning light is on.

 

[Gary RV_Wizard]

The "1/4 tank" is just an approximation. No rocket science - the people who assemble the motorhome just stick the generator fuel pick-up only part way into the tank. "Part way"  is probably just eyeballed, so it is quite possible for there to be some variation. Maybe even a lot in a few cases.  And the fuel gauge on the dashboard has no correlation to it either.

 

[Gary RV_Wizard]

One failure mode of the Onan 7500 is a shutdown after exactly 5 minutes of operation due to a failed coolant temperature sensor. The primary code will be a 3 and the secondary a 24.  If the controller board does not get a reading from the temp sensor for 5 minutes, it shuts down to make sure it isn't overheating.