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Genset Fuel Filter Change


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Did Genset service this AM on my Onan 12.5 HDCAB.  The worst part by far was removing and reinstalling fuel filter.  The fuel line coming from the pump is steel, the one to the engine is rubber.  How much easier it would be if that steel line was rubber too, like the newer models.  Then I could just bring the whole assembly out to change.  Has anyone changed that fuel line on a 12.5HDCAA or 12.5HDCAB?


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Mine is 7.5 kw but probably has the same issue. I hated that steel line. Very difficult to start the threads. I put a flex line in place of the steel one. Bought a flex line which was a little long and made a loop up and then back down. One end fitting on the new line was good to go into the end opposite the filter. On the filter end I cut the flex line and put a 90 degree barb fitting into the flex line with a hose clamp.

The only remaining issue is that all the fittings must be tightened very, very tight to stop leakage. Best to use flare wrenches and almost need to use a cheater on them. I have inspected the flares and they are either new (such as on the new filter) or there is no damage on them. Anyone else have this tightening issue?



02 Knight


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@scottjo02, Yes. I recall having to tighten the fittings on the 7.5 Onan in my Dynasty.  I always thought that working from underneath made tightening those fittings more difficult.

The 12.5k and 10k have a door for side access; that makes changing the oil filter an easy task, but on mine, the fuel filter change is a knuckle buster... there's barely enough space to make a 1/6 turn with a flare wrench.  A flare crowfoot would make that a little easier.    My 12.5 has a steel fuel line going from the fuel pump thru an internal wall.  One way would be to get a shorter steel line from the pump thru the wall, then go the rest of the way with a rubber hose.  Hoping someone has done this; looks like you need to take the case off.



 The newer 12.5 has rubber fuel lines both to and from the filter, and they're curved and long enough to actually pull the filter out.  Filter mounting looks completely different ... see below.



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Guest Ray Davis

I have a 7.5 kw gen and when I replace the filter I remove the drivers side cover.  It takes a few minutes but beats having diesel running down your arm.    Removing the side panel makes the whole job easier.

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