Onan Marquis Gold 7000
 

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

Re: Onan Marquis Gold 7000
 

Almost the same deal changed regulator and that fixed everything

Re: Onan Marquis Gold 7000
 

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

Re: Onan Marquis Gold 7000
 

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

Re: Onan Marquis Gold 7000
 

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

Re: Onan Marquis Gold 7000
 

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

Re: Onan Marquis Gold 7000
 

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

Re: Onan Marquis Gold 7000
 

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.

Re: Onan Marquis Gold 7000
 

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......

Re: Onan Marquis Gold 7000
 

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.......

Re: Onan Marquis Gold 7000
 

It shut down again. This time it is a code 41.
GENERATOR ROTOR FAULT—CODE NO. 41
(Controller unable to sense field or output voltage)
Restarted and ran for about 15 seconds and gave the code 36 again.
Is that a controller issue or generator issue?
Dan

Re: Onan Marquis Gold 7000
 

Thanks for the info Rich. I will try the fuel line crimp and see how it shuts down. I agree about the deflector. This genset has run for 2000 hrs without one, why would that be a problem now. Might have to bite the "controller" bullet. Where is the controller located? Is it behind the stop/start panel?
Dan

Re: Onan Marquis Gold 7000
 

Rich,
After crimping the fuel line and observing how it shuts down, it's definitely different than how it has been shutting down. It shuts down abruptly when running normally. I will order a new controller. Mine is the HGJAB model. Is the controller the 300-5047 or 300-5374?
Thanks again.
Dan

Re: Onan Marquis Gold 7000
 

The ECU is mounted behind the start/stop switch in a second section.

You have to remove the battery cable....remove that front switch box section. 1 10mm bolt to remove it.

3 10mm bolts hold the rear box with ECU inside.
2 bolts forward.....1 bolt in the rear....behind the box and down...
1 connector with a snap lock disconnects the ECU from the wiring harness......Pull it and examine the pins carefully for any that look discolored.....might be your problem but probably not...

ECU is held in that rear box with 2 screws......slide right out....
Heat sink on one side gets some air from the machine when it runs...


2000 hrs......is well more than enough to have this problem.....

Make sure the brushes are good if you did not check them....they also fail and cause odd shutdown faults.....easy to check...

Look at the upper area of the generator end....behind the switch area.....
2 wires going into a holder....one 10mm bolt......
Brushes are there....remove bolt....slide brush rig out.....brushes are about an inch long when new.....If one is bad it will cause the surface it rises on to be in bad shape.....sandpaper on a wooden stick will clean it up if needed.....they car copper slip rings....
Brushes are easy to get.....#212-1303 and probably also available from Parts for Techs...

Re: Onan Marquis Gold 7000
 

Rich,
Thanks for the advice. I removed the Controller and checked the brushes. They looked good but are only about 1/3" long. I ordered a new brush block and brushes. I'll post again after I change the parts and run the generator.
Dan

Re: Onan Marquis Gold 7000
 

Update.
I installed the new ECU and brushes. Generator has been running now for over 4.5 hours w/o shutting down.
FYI. I purchased the ECU from a company called Flight Systems in PA. It has a 2-year warranty. $329
Thanks again for your help Rich.
Dan

Re: Onan Marquis Gold 7000
 

Glad to help.

We have sent many PC boards to Flight for testing and repairs.
We also have used some of their replacement components for Onans like voltage regulators.
The control sold by ASAP is probably a Flight....

Re: Onan Marquis Gold 7000
 

Found my answer

Re: Onan Marquis Gold 7000
 

Rich,
I noticed that my air compressor in my trailer was starting slowly. I checked and generator was only putting out 91VAC.
I reinstalled the old controller and the generator output was back to 119VAC.
I sent the new unit back to Flight Systems. They told me that the new controller (300-9374) was checking good. I think they are having trouble with their unit since my old controller makes the generator output normal.
They were going to recheck their controller.
I'll let you know what they say.
Dan

Re: Onan Marquis Gold 7000
 

They are guaranteed I believe so ask for a replacement.

I have had some that were not right from them.

Electronics !!!

Re: Onan Marquis Gold 7000
 

UPDATE:
After talking to Tom at Flight Systems. He gave me the resistance readings and pinouts to check brushes/stator/quad readings. All checked OK. After another phone conversation with him, He wanted me to check the freq output of my generator. I was only getting 55 hz. He said that their modules will decrease the output voltage to 90VAC if the freq drops below 57 hz. I adjusted mine up to a no-load setting of 62 hz. Looks like the governor spring is weak (probably due to heat).
I hope all this info may help someone else.
Dan

Re: Onan Marquis Gold 7000
 

I assumed you had already verified your generator was running at the proper speed......It would always be checked along with voltage and at the same time.....

HZ or Frequency is engine speed on any NON inverter type gas or diesel generator....

Re: Onan Marquis Gold 7000
 

As it turns out. When I tried to check the freq, (with lights, ACs, etc.turned on) my meter was too sensitive and would get crazy readings (259, 165, 312). I found out this is due to noise being backfed to the system with all of the load connected. When Ichecked the freq with no-load, it gave me a steady reading. That's when I found the real problem. No I'm wondering if my old controller is bad or the freq issue was causing the shutting down?
Dan

Re: Onan Marquis Gold 7000
 

I use Fluke meters and really can't think of why you would have a noise problem causing a meter to read incorrectly.....

I have 2 Flukes and they read frequency with or without loads applied with zero issues.......

Re: Onan Marquis Gold 7000
 

The meter I was using is by Amprobe. If I checked the freq without any load, it was steady at 62 hz. As soon as I turned on any device, (lights, AC, air comp), the freq reading on the meter would jump around.
Dan