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Hank F.
Hank F., RV tech - emphasis on gensets
Category: RV
Satisfied Customers: 14994
Experience:  RV tech since the beginning of the millenium.
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Onan emerald 3 propane fuel generator will start then die.

Customer Question

onan emerald 3 propane fuel generator will start then die. sometimes starts and runs fine.
tried holding start switch on still dies. oil level is full. Its in my fith wheel trying to everything I can before I have to take complete unit in to dealer. Any help
Submitted: 1 year ago.
Category: RV
Expert:  Randall replied 1 year ago.

When was the last time you had the LP pressure at the tank regulator checked and adjusted? That would be the first place to start if you haven't done that in the last year. Some are adjustable and some aren't. If you need a new one I would go with a Marshall as they are about the best one out there. About $40 or so. Once we rule that out we can go further as all follow ups are included in our fee.

Customer: replied 1 year ago.
all this was serviced two weeks ago. also by passed propane regulator, went straight to carb with propane source. same thing. Starts then dies. had problems on the road. traveled two more days. stopped and set up started right up. shut unit off havnt been able to start it since. cranks, starts then dies.
Expert:  Randall replied 1 year ago.

When you say "serviced"......what all did thy do? Many shops never bother to check the LP pressure. If this uses low pressure LP, you can't just take it out of the tank directly. It has to be at the correct pressure.

Customer: replied 1 year ago.
I told them the problem that was going on, and of course while it was in the shop it started and ran fine, I can only assume that they would do all the checks and services. this propane conversion is two years old. it started for me prior to leaving on vaction.
one other thing, generator was running fine air conditioner on, to reduce the load I switched the refridg to gas, heard the transfer switch click, generator reved up, died, hasnt started since. I was told possibly a bad circuit board, this advice was based on the intermittent condition.
Expert:  Randall replied 1 year ago.

Pretty strange...........I will go ahead and opt out of this question as we have a really good Onan tech here that works on these for a living. I suspect he can get this sorted out for you. I don't know if he is around this week-end or not. I will keep an eye on this as I am curious as to what he might think is the problem. I don't know any good reason for this not starting when that is all you did.

Expert:  Hank F. replied 1 year ago.

What is the model number of the genset?

Customer: replied 1 year ago.
Expert:  Hank F. replied 1 year ago.

The single most common cause of this issue is that the set is no longer producing electricity.

Remove the control panel from the front of the genset.
Set your meter to ACV.
Connect the black lead to a good ground.
Connect the red lead to the back of the circuit breaker (either one), on the terminal farthest away from you.
Press and hold the start button for 6 - 8 seconds, and note the voltage.
How much voltage is there?

Customer: replied 1 year ago.
140 v
Expert:  Hank F. replied 1 year ago.

If you are getting 140V at the breaker, you need to connect a frequency meter to the circuit breaker and test frequency while it is running.

What frequency do you get?

Customer: replied 1 year ago.
Out of frustration, I just started and ran the gen set on wd-40. Clearly I must have a propane regulator issue
Expert:  Hank F. replied 1 year ago.

It is very possible.

There is a diaphragm inside the demand regulator that can get dirty or stiff, and create problems.

But unless you have had gaseous fuel training and have the proper equipment, this is not something you can test yourself. The regulator is not inexpensive, and I really don't recommend replacing it unless it has been tested.

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