The Cummins Onan QG3300LP which is often referred to as a
3.3KYFR-4858 or even by its part number
AO55EE855 is an LPG generator capable of producing 14.3 amps maximum power. This compact quiet
generator (68 dB) only weighs 83 kg has proven to be a very reliable workhorse. One of the key
factors to keeping your Cummins Onan generator reliable is regular servicing and keeping to the
When engines run on LPG the engine oil does not become
anywhere near the same as an
engine that runs on petrol. This key factor will allow increased running time as well as fewer oil
LPG is a gas, unlike petrol which is a liquid, using LPG as a
allows spark plug intervals to be
If you read the periodic maintenance schedule in the operations manual you will see that the schedule
for petrol and LPG are the same, in reality, you can increase the intervals as follows.
Periodic Maintenance Table
The first oil change should be kept at 20 hours, after that the engine oil
can be increased to every 300 hours. Also, the 500 hours can be increased to 600 hours, then I
would advise the brushes to be changed at 1200 hours if the generator is being worked at
75% load and above.
Periodic maintenance Schedule
The 1200 hour service
This service requires the following:
The parts to carry out the service are as follows:
Replace the brushes
Once the brushes are fitted then you reverse the procedure by re-fitting the flywheel and the
That part of the service is now complete.
Replace the spark plug
With that sequence of operations completed we need to
generator to get it warm ready to change the engine oil.
Check and adjust the valve clearances
Replace the air filter
Change the engine oil
The lubrication system is only splash fed, this means the engine has no oil filter
The final part of the service is to run the generator up and check the output
This should be measured with no load (maximum 249 volts) and on full load with a maximum of 215
The HZ the generator produces is directly proportional to the RPM. 1 x HZ increase
output requires the engines RPM to be raised by 60.
Now check the RPM of the engine and without a load. You need to read no more
than 51.5 HZ on
RPM) and no more than 52.5 HZ with no load 3150 RPM.
The above image shows the use of the rev counter. This reading was taken with no
would be producing 50.97 HZ. Now you need to check the engine RPM when on load. Once you are satisfied
you have set
the engine within spec the service is then complete. A word of warning, if you do not get the RPM within
spec the generator will automatically stop on code 14 – over frequency or 15 – under frequency.
All that's left to do is to put the generator back into the vehicle so it can produce prime power
for another 1200 hours.