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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 13581
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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I have an ONAN Quiet Diesel 7500 in my RV. Lately it is hard

Customer Question

I have an ONAN Quiet Diesel 7500 in my RV. Lately it is hard to start and doesn't want to run under a load. Not sure where to check to see what the problem could be.
Submitted: 1 year ago.
Category: Small Engine
Expert:  Hank F. replied 1 year ago.
Hello, my name is ***** ***** I am going to assist you with this. What is the full model number of the genset?
Customer: replied 1 year ago.
The other numbers on the Onan Quiet Diesel 750 is 7.5HDKAJ11451H. Are these the numbers you are looking for? It is installed on my 2005 Fleetwood Excursion.
Expert:  Hank F. replied 1 year ago.
Those are exactly the numbers I needed - thank you. Lets see what fault code is set in the controller.Go to the genset and use the switch on the set itself.Press 'Stop' 3 times within 5 seconds. The light in the switch will startflashing.If the light flashes 3 times, pauses for 3seconds, and flashes 3 more times, press and immediatelyrelease 'Stop' one more time.This will put the controller into Fault Read Mode.The light will flash (X) number of times, pause for 1 second, and flash for(X) number of times again. Count the flashes before and after the pause.This will be the Fault Code.Example: 2 rapid flashes, 1second pause, 5 rapid flashes is a Fault Code 25.There may be more than one Fault Code stored, so watch the lightvery carefully. If there is more than one code, it will display them all inorder, and then start over again. Be very careful not to misread a first level fault code (singledigit code) as a second level fault code (double digit code).The way to tell the difference is by the length of the pauses.There is a 1 second pausebetween digits of a second level code, and a 3 second pause between codes.For example, if it is flashing 2 times, 1 second pause, flashing 2times, 3 second pause and repeating, then this is a second level fault code of22.If it is flashing 2 times, 3 second pause, flashing 2 times, 3second pause and repeating, then this is a first level fault code of 2. What Fault Code are you getting?.I have made a short video showing this procedure.Click here to download it.
Customer: replied 1 year ago.
It just gives a rapid 3 flashes then pause and then constantly goes around to 3, pause, 3 pause as so on. So I don't know if that means 3 or 33 or 333 or what.
Expert:  Hank F. replied 1 year ago.
You need to pay attention to the length of the pauses between flashes, as shown in the video.This particular unit has both a code 3 and a code 33. It is critical to make sure to properly read the code.