Onan Marquis Gold 7000

[voltdr]

Help,
While pulling a full load (2 A/C units, and stuff) my generator runs fine for about 30-45 minutes. Then just shuts off. It doesn't give any codes. It restarts immediately. I thought it may be getting hot. I put a fan on it and it seems better until I turn on the second A/C unit.
Any thoughts?
Dan

[sgasman]

Almost the same deal changed regulator and that fixed everything

[Rich Biebel]

If it shuts of immediately it is the Control Board. A common problem. Heat does cause it to fail. I have changed many of them. The machine might have low hours as I have changed them on fairly new machines as well as ones with many hours.

300-5047 is the part number up until about 2 years ago. Easy to change but a very expensive part.

You can buy a Cummins-Onan part or now an aftermarket is available...


http://www.partsfortechs.com/asapcar...yword=300-5047

[Sean Marconette]

Dan,

With Rich's help I was able to resolve the problems on my Marquis Gold 7000. I had replaced the control module with the factory replacement. A few years later same issue but worse, as the generator would not restart until everything was back down to ambient temp. I then replaced the control module with the ASAP. Problem solved. I had codes that were misleading with the OEM module.

If you are bored,
http://classracer.com/classforum/showthread.php?t=41189

Sean

[voltdr]

It's unusual because it would restart immediately after shutting down. I even put a fan blowing on the genset but that didn't seem to help. I replaced the fuel filter and the generator ran better the next day. I'm going to pull it out and check the plugs and make sure there aren't any obstructions restricting the air flow.
Thanks for all of the suggestions and help.
Dan

[voltdr]

Sean,
I read your link. I have suspected that could become a problem. When I put a fan on it I try to place it so it blows the exhaust away from the inlet. I am going to fabricate a duct to deflect the exhaust away from the air intake.
Thanks for the help.
Dan

[voltdr]

Rich,
I have replaced both fuel filters, checked the screen for obstructions (none). Installed a deflector to direct the hot air away from the genset. Ran generator for about 2.5 hours with both A/Cs on. Shut off but gave me a 36 code this time.
Dan

[voltdr]

After reading the Onan manual for code 36, It said to check the fuel supply and also the air filter. I put in a new air filter and it seems to be running good now. I'm going to let it run for awhile longer.

[Rich Biebel]

Code 36 is a common one. Points to a loss of fuel and means the ECU did not shot it down.

The 2 items most likely to cause these shutdowns are the fuel pump and the ECU/Controller.

The fuel pump and solenoid at the base of the carbs fuel bowl are both energized on the same circuit.

If the engine shuts down abruptly when one occurs.....it IS the ECU. The voltage for the pump and carb solenoid is dropping out from the heat.
May or may not restart immediately or after sometime....Typical scenario.

If the engine starts running unstable and lopes up and down for a short time, it is the fuel pump. Carb still has fuel in the bowl and once pump quits, it takes a while to up the fuel remaining in the bowl.

The pumps are piston type and tend to fail and often do.

I change them both and just did for an RV customer a few weeks ago with this intermittant shutdown issue. His wife needed the AC and he had no interest in maybe this or maybe that......change both and lets get it done now.

There is no fix for this other than what I describe.

Cummins has 2 different heat deflectors now for a machine that will help direct the hot air away from the inlet side...but my experience with these machines says they are not going to fix units with intermittent shutdowns due to a bad ECU......

I have changed many ECU's on gas engine units and diesels.....all for the same issue...loss of power on the circuit that supplies the fuel pump....

It needs to be relayed in my opinion......

[Rich Biebel]

Originally Posted by voltdr

After reading the Onan manual for code 36, It said to check the fuel supply and also the air filter. I put in a new air filter and it seems to be running good now. I'm going to let it run for awhile longer.

It is definitely not the air filter.

Crimp the fuel line going to the filter so no fuel can get to the pump.

Let it run......Observe how it shuts off......

Read the code...it will be a 36...

If that is similar to how your machine quits...it is the pump.

I have been working on these machines for close to 15 years....

I know them as well as anyone.....and know just about every scenario of failures....

I did learn a new one this week.......