Onan problems
Hi. Looking for help with my gen. I did a lot of searches and applied all the suggested solutions and still no luck. Here is a recap: Onan microquiet 4000, Model 4KYFA26100K, 2007, 600 hours A few m...
Forum Discussion
A bit of info about the normal operation of an Onan fuel pump might be of some value to anyone interested in the topic.
I had the opportunity to tear one apart that came out of a Onan 5500. The fuel pump consists of a solenoid that is activated with 12 Volt pulses that in turn cock a spring and the spring provides the fuel pressure (a spring loaded solenoid that acts like a piston pushing the gas through a check valve). There is no feed back loop to the pulses, they just come a couple every second or so and cock the spring whether it needs cocking or not. That is what makes the noise which can be heard when pushing the priming switch. As far as I could determine the O rings around the solenoid (piston) were not up to maintaining the fuel pressure. So the worse the O ring the more noise because of the longer strokes.
I was able to successfully replace the Onan pump with a 3rd party pump from an auto parts store. They too work on the basis of a spring driven piston (solenoid) through a check valve.
I had the opportunity to tear one apart that came out of a Onan 5500. The fuel pump consists of a solenoid that is activated with 12 Volt pulses that in turn cock a spring and the spring provides the fuel pressure (a spring loaded solenoid that acts like a piston pushing the gas through a check valve). There is no feed back loop to the pulses, they just come a couple every second or so and cock the spring whether it needs cocking or not. That is what makes the noise which can be heard when pushing the priming switch. As far as I could determine the O rings around the solenoid (piston) were not up to maintaining the fuel pressure. So the worse the O ring the more noise because of the longer strokes.
I was able to successfully replace the Onan pump with a 3rd party pump from an auto parts store. They too work on the basis of a spring driven piston (solenoid) through a check valve.
