After reading another post on generator filters this morning, my mind sort of drifted off...........In a DP (mine is a 2005 Fleetwood 39S Excursion with a Cat C7 and Onan 7.5 and a 100 gal fuel tank) how often does the generator fuel filter really need to be changed?Back at the lower right corner of the main radiator my engine fuel filter has a clear bowl that I check all of the time for water and junk. Never had a problem with any water, never seen more than maybe two drops in it. I've been lucky, buy most of my fuel at Sam's Club when they're handy.The main engine takes fuel from the bottom of the tank. The generator engine takes fuel from someplace higher, from a 1/4 to a 1/3 tank level - therefor it's not taking fuel from the bottom of the tank where the water and junk would be if there was any.I usually ignore the mfg's change recommendations. Depending on my situation (severity of service, fuel conditions, and so on) I usually change my lubricants and filters sooner or later than the recommendations by the mfg. So after all of the above, since the generator is drawing fuel from someplace higher up in the tank unlike if this was a stand alone generator drawing fuel from the bottom of its own tank, and that I've never gotten water or junk in my main fuel filter from the bottom of the tank, how often do I really need to change the generator fuel filter? I would say not very often - where is it going to any contamination from?Your thoughts?Bill

From reading your post it appears to me that you are wanting folks to justify your thoughts of not having to change the genie fuel filter because of ????? I personally would not do that as the small price for the filter in question vs the possible cost of something going wrong is a mute point. There are/will be times when lack of use/time in service, etc would appear to support your thinking on maintence items. Your rv, your choice. I'm not one that thinks that way as these thinks can/are "expensive" to fix.

As I said, I often change filters sooner than recommended. I just can't find a reason for the generator filter to get dirty. I guess I could change them a couple of times a year just to be safe. I do carry two spares of all the filters with me and I think three or four main fuel filters. I do like to be safe, but don't like to waste money either.Bill

What IS the recommendation ?How easy is the filter to get to ?I see no reason NOT to go with the recommendation. The little gen filters can't be THAT expensive......can they ??

I change my engine primary fuel filter when it will not make 100% power going up a hill which has been around 25K miles ... 500 hours. My generator is approaching 600 hours and it's second oil change on the original fuel filter. Will change it when I have it opened up for the oil change.Different strokes for different folks.PS: I usually cut my filters open... You can learn a lot. I also usually put a clear inline filter before the primary making it easier to see what's going on.

I believe that Cummins Onan specifies every 500 hours for the fuel and air filters, every 150 hours for the oil and oil filter and spark arrester.

Thoughts on how often to change a DP's generator fuel filter

20 Replies

JumboJet
Explorer
Aug 25, 2015
Changed my fuel filter this afternoon. Less than a cup of diesel fuel drained into the pan I held while loosening the lines. 15 minute job. Primed according to instructions and it started up and ran smooth.
Snomas
Explorer
Aug 24, 2015
My gen set shut down after 40hr of running and found out it was caused by the fuel filter that had 150 hrs on it. Put in new filter and now runs great.
Vulcan_Rider
Explorer
Aug 24, 2015
ssia2485 wrote:
Those type filters are easily changed and you can go well over 500 hours if you are using the generator regularly.

I would absolutely agree with that....IF it were a gas engine.

Diesel fuel tends to accumulate more and different kinds of contaminants though, including MOLD......especially where it's hot and damp.
ssia2485
Explorer
Aug 24, 2015
Those type filters are easily changed and you can go well over 500 hours if you are using the generator regularly. Cant hurt to change it sooner though. Best to carry an extra one just in case. I use my generator a lot.
DSDP_Don
Explorer
Aug 24, 2015
When I service my generator, everything gets done. Oil, oil filter, fuel filter and air cleaner. I do it between 12-18 months depending on usage.

There are a couple of secrets to change the fuel filter. First, use a fuel line wrench to keep from ruining the fuel line nut. Second, I save plastic plugs, like the tip off of a tube of silicone. I use it to plug the fuel line once it's off. Third, tie a rag around both wrists before you start. This keeps the diesel fuel from running down your arms.

Lastly, never use a trouble light (110 volt) when changing fuel filters.
Executive45
Explorer III
Aug 24, 2015
FormerBoater wrote:

While it is 500 hours, Speedco changes mine every time I get the genny serviced (100-125 hours per year).

They do so many it seems to be very easy for their techs.

THIS is what I do as well...Dennis
holstein13
Explorer
Aug 23, 2015
I just checked my Cummins / Onan generator manual. It says to change the engine oil and oil filter every 250 hours and to change the fuel and air filter every 500 hours. That seems reasonable to me.
FormerBoater
Explorer
Aug 23, 2015
FIRE UP wrote:
Well,
First off, GETTING to the fuel filter on a 7.5QD is easy. CHANGING it is another story. Because of the way that filter sits in it's area, and the way the lines attach etc., it's quite often going to put diesel down your arm and, into your arm pit. Not always but, often. I keep a hand full or nice clean rags ready and, usually don't have to fight that flow of fuel. With the correct tools, some patience and, maybe a little luck, I can change that filter in about 5 or so minutes.

Now, one thing, it does make for an easier time if, your generator is on a slide. That helps because it slides out to where your access to the bottom is not as hard. I've also changed it by pulling the side panel off (another benefit of slide out generators). When that panel is off, it makes it REAL EASY TO CHANGE IT.

As for the OP trying to justify his less than normal time change interval, well, that of course is up to him, its his. I can see his reasoning and, it sort of makes sense. But, I think that there's still some suspended contaminates, possibly rust or, dirt particles etc. that are MAYBE floating around at various levels of that fuel tank. And, eventually, that generator filter will pick those up. Just how soon, who knows?

Like other posters have stated, filters are cheap insurance. I change the one and only fuel filter on our coach, annually whether it needs it or not, based on mileage etc. I change the oil at more of a frequency too, based on my mileage, not the recommended. Again, it's cheap, compared to replacing any of the expensive components that are tied into that engine and, the engine itself.
Scott

While it is 500 hours, Speedco changes mine every time I get the genny serviced (100-125 hours per year).

They do so many it seems to be very easy for their techs.
FIRE_UP
Explorer
Aug 23, 2015
Well,
First off, GETTING to the fuel filter on a 7.5QD is easy. CHANGING it is another story. Because of the way that filter sits in it's area, and the way the lines attach etc., it's quite often going to put diesel down your arm and, into your arm pit. Not always but, often. I keep a hand full or nice clean rags ready and, usually don't have to fight that flow of fuel. With the correct tools, some patience and, maybe a little luck, I can change that filter in about 5 or so minutes.

Now, one thing, it does make for an easier time if, your generator is on a slide. That helps because it slides out to where your access to the bottom is not as hard. I've also changed it by pulling the side panel off (another benefit of slide out generators). When that panel is off, it makes it REAL EASY TO CHANGE IT.

As for the OP trying to justify his less than normal time change interval, well, that of course is up to him, its his. I can see his reasoning and, it sort of makes sense. But, I think that there's still some suspended contaminates, possibly rust or, dirt particles etc. that are MAYBE floating around at various levels of that fuel tank. And, eventually, that generator filter will pick those up. Just how soon, who knows?

Like other posters have stated, filters are cheap insurance. I change the one and only fuel filter on our coach, annually whether it needs it or not, based on mileage etc. I change the oil at more of a frequency too, based on my mileage, not the recommended. Again, it's cheap, compared to replacing any of the expensive components that are tied into that engine and, the engine itself.
Scott
Kayteg1
Explorer II
Aug 23, 2015
Lot of manual are following general rules written 20 or 50 years ago.
They do not take into account that about decade ago all gas stations tanks have been replaced with dual walls and the common before problem with condensation and corrosion in fuel doesn't exist anymore.
My RV are not driven a lot, but on my truck the fuel filter recommendation was 30k miles.
I made 89k before the engine start slowing down on the grade.
Having tools handy took me 5 minutes on the side of the road to replace the filter.
Most of big engine also have air filter minders. I installed one also on wife car and those routinely let me drive 100,000+ miles on air filter on California roads .... or 2000 miles on dusty Mexican roads.
YMMV
Generator fuel filter? What is it? ;)