DougC 2,641 #1 Posted May 13, 2016 I installed a new fuel filter a month ago on my 88 520H Onan and can now see if there is fuel in the filter. After installation and initial start up and run time of about 15 seconds the filter filled to about 1/2 way like my 95 520H runs all the time. A few days ago after I mowed for about an hour I pulled up to the garage and hopped off the tractor seat to grab a drink of water and glanced down to see if the air intake screen needed to be cleaned off as it idled and noticed there was about 2 drops of fuel in the filter as it was still sitting there running. I shut it off and went in the house for lunch. ( Gunsmokes on at noon....) An hour later I came back out and started it up and very quickly the fuel filter was 1/2 full of fuel. Have any of you guys had this happen on yours? I don't know if I have a fuel pump failing or why a cool down would make any difference to a fuel pump issue or if the old 1,375 hour Onan is having valve and low vacuum related problems. Share this post Link to post Share on other sites
lynnmor 6,704 #2 Posted May 13, 2016 I have 3 520's and they all act like that, always did. Share this post Link to post Share on other sites
DougC 2,641 #3 Posted May 13, 2016 Huh.... I never noticed my 95 doing that but maybe I just wasn't paying attention. It still ran fine, had no surging or fuel starvation symptoms. Interesting.......It may be a normal condition. Still bugs the H@LL out of me though....... Share this post Link to post Share on other sites
WheelHorse_of_course 99 #4 Posted May 14, 2016 This observation is a common one, but this is perfectly normal. As long as fuel is going in, and fuel is coming out there is no need for there to be fuel in the filter per se. Just one of those weird things! 1 Share this post Link to post Share on other sites
953 nut 51,018 #5 Posted May 14, 2016 This is about like the post the other day about PTO clutch temperature; if it ain't broke, don't fix it. Runs fine, enjoy some more seat time. 1 Share this post Link to post Share on other sites