Onan 7500 Clicking Sound

[erniewjr]

My Onan 7500 has made a clicking sound the last two mornings like the glow plugs are sparking. I can stop it by quickly pressing the start switch. I am going to be away from the motorhome for a couple of weeks and don't want the clicking to happen when I am gone. I don't want to put the motorhome in storage mode since I want the heater to run if the temperature drops. What can I do to fix the problem or disconnect the circuit that causes the glow plugs to start clicking.

[wolfe10]

First suspect is that you are hearing the electric fuel pump. You can put your hand on it and feel it pulsing. OR, you can disconnect the wire to it and see if the noise stops.

It is normal/desired for the fuel pump to operate while the glow plugs are heating up.

[dickandlois]

erniewjr,

Good to see your first post! been a member for awhile!

Try this little test.

Press the stop side of the generator start switch and hold it down for a few seconds. This puts the generator in the prime mode.

You will hear a clicking sound. Does it sound like what you mentioned in you post?

Remember, there are 2 start / stop switches. One located outside on the generator, same area as the circuit breakers and the one you use inside the coach.

If you a trying to start the generator this is normal. IF not then one needs to look for the switch or something in the pump power circuit that is supplying power to the pump when its not supposed to be there.

If you are going away for a few days and the pump is cycling, you might want to disconnect the 12 volt ground wire at the back / bottom connection on the generator and do some testing when you return.!!

Rich.

[elkhartjim]

Thanks, Brett. I've always wondered what that clinking noise was and now I know.

[erniewjr]

I pressed the stop button and the sound is the same clicking sound I have been hearing. I will disconnect the 12 volt ground at the pump while I am gone. Thanks to everyone for the assistance.

[dickandlois]

Ernie,

Disconnect the ground at the DC Supply terminals, where the battery connections are.

I'm thinking that if you disconnect the ground at the pump, there is still the possibility of power going to the Glow plugs.

One more question, do you have a auto start system on your coach for the generator?

Rich.

[wolfe10]

Rich,

If the power to the pump is disconnected and the noise quits, he has ruled out the glow plugs and their circuit as the source.

If he disconnects both, he will not know whether the glow plugs or fuel pump is the source.

[dickandlois]

Rich,

If the power to the pump is disconnected and the noise quits, he has ruled out the glow plugs and their circuit as the source.

If he disconnects both, he will not know whether the glow plugs or fuel pump is the source.

Correct Brett! just not sure he wants to take the time now to run some tests, so I'm thinking of completely disabling the circuit until he returns from his trip.

Rich.

[erniewjr]

Rich,

I do have a auto start system but it is in manual mode. I will disconnect now then try to correct the issue when I return.

Thanks,

[john_harris]

While have not had issue with "clicking sound", I am glad to see Rich's comment about prime mode. When running generator on the road, I have failed to turn off generator before getting to the fuel threshold and run the line dry. It is then difficult to restart after fill tank. Sounds like I can use this to prime system and not keep cranking the genset.

Thanks, Rich,.