Fuel filter, to prefill or not to prefill?

[CountryFit]

My engine is a Cummins ISC with 2 diesel fuel filters: FS1022 (bigger) and FS1212 (smaller). In the past, I've always prefilled filters regardless oil or fuel, but I just noticed a diagram on the side of FS1022 saying "Do not prefill for ISC". Has anyone run into this? What did you do?

(Thought - If an ISC engine has only one filter, it might make sense to do so to prevent from contamination; but my engine has 2 filters, and FS1022 is a primary filter, will that make a difference?).

[Mjay]

I think you have the wrong filters on. FS stands for fuel separator, which is the FSXXX, next filter should be a FFXXXX, where the FF stands for fuel filter.

The FS XXXX is to separate any water/condensation that enters the system, the FF XXXX filters the fuel.

[CountryFit]

yeah it sounds like weird but that was how it was set up. initially i was wondering why they used two separators... according to cummins, there should be only one filter, the coach manufacturer decided to add another. the set up was from country coach.

[Mjay]

I have the FS 1212, then a FF 5324. I realize they are not the same rigs.

Of all the diesels i have worked on, they always has a separator, followed by the filter.

Yes, you can pre fill the filters, just be carefull to keep the dirt out.

[lanerd]

My owner's manual says it not necessary....just cycle the ignition key two or three times and that will fill the filters. My previous mh with a C7 Cat had a small hand pump on the side of the filter housing and all you had to do is pump that a few times to fill the filter (after it's been installed, of course).

However, if you do fill filters first, make sure you do not get any fuel in the center hole....only on the smaller holes that surround the large center hole.

[NHRA225]

Always-- Always Pre- Fill your fuel Filters !
Oil Filter Too !

[Dr4Film]

My 2002 Monaco Windsor with the ISC 350HP came spec'd for this filter set-up.

The Primary filter came with the Racor S3201T (P) and the Secondary came with the Fleetguard FS1022 (S).

When I replace the top part of the Primary filter I use Fleetguard FS1242 (P) 10 mc. The bottom part is a plastic clear bowl which gets used over again.

Both of these are water separator filters BUT that's the way Monaco had setup the engine from the factory.

I do have other filters in my list of records that will work on this engine.

Some people claim that you need to have a 30 micron filter for the Primary and a 10 or under micron filter for the secondary. I don't disagree BUT I have been using the 10 / 10 micron filter for years now and it works for me so I haven't been in a hurry to switch to something different.

Some people say to use the fuel pump to fill the filter before trying to start but my filters have always been pre-filled with clean diesel by the service techs before starting the engine.

If you plan to change your own filters, always change one and then start the engine making sure it runs OK before changing the other one.

Dr4Film ----- Richard

[CountryFit]

thank you all for the info.

richard - looks like monaco and country coach do the same thing. i just googled web, fs1022 is 10 micron filtration and fs1212 is 20 micron. it has been like this from day one and engine is still good at 70kmi

agree with lanerd and chuck, prefilling to the small perimeter holes should be no harm.

[Dr4Film]

Originally Posted by CountryFit

thank you all for the info.

richard - looks like monaco and country coach do the same thing. i just googled web, fs1022 is 10 micron filtration and fs1212 is 20 micron. it has been like this from day one and engine is still good at 70kmi

CountryFit,

Make sure that your Secondary it smaller or the same micron than your Primary filter not larger.

Dr4Film ----- Richard

[jimbo2013]

I use 10 & 2 mic, did a lot of research and works well.

there are several water separators as good or better than Racor for half the cost

[dons2346]

I do not pre fill the fuel filters as it is not required for the ISC motor. Put them on dry and use the ignition switch to cycle the fuel pump to fill the filters.

Your first filter in line should have the clear bowl on the bottom and have the "water in fuel" sensor on it and it is a 10 micron filter (FS 1003 or FS 1022 depending on installation). The second filter is the 2 micron filter(FF5488)

[CountryFit]

well, i am not sure which one is primary and which one is the secondary. below photo shows my actual filters - at the left the big one is fs1022, at the right the smaller is fs1212. both have a water valve at the bottom.




does fuel go to the smaller one --> lifter --> the big one? I thought it is the other way around. if latter, there will be a problem, the big one is a 10 micron filter and the smaller is a 20 micron... but from the spacing, apparently CC made it impossible to install other way around...

[Bob&AnnaMari]

This is a very interesting thread. I would strongly suggest going with whatever the documentation on your coach says. My documentation is very clear that you do not pre-fill the filter.

Granted I have only changed mine twice, but in each case there has been no problem having the fuel pump circulate the fuel until all the air is evacuated. My documentation clearly states that there is a definite possibility of fuel contamination if you pre-fill.

I just figure if mounting them empty works, why fiddle with filling them first?

[Dr4Film]

CountryFit,

To be absolutely sure, I would trace your fuel line coming from your Fuel CAPS or Fuel Rail System which is on the engine back to your secondary filter and then you will know which one it is.

Obviously your Primary and Secondary are different than mine. My Primary has the water bowl at the bottom and the Secondary has the Water-In-Fuel sensor at the bottom.

I have attached photos of my fuel filter system, Primary on the LEFT, Secondary on the RIGHT as you are facing the engine compartment.

Dr4Film ----- Richard