ISC Fuel Filter Change

[tmw188]

So I did my first fuel filter change without pre filling them, I did the dry install method and it worked out. I wanted to do this while not being on the side of the rd trying it for the first time. So here’s my question. I noticed some small black chips in the primary filter bowl. Is it possible it could be PCs of fuel hose? I plan on looking at them closer tomorrow after I pick them out and lay them on a paper towel.

[tmw188]

There’s a great read in the current issue of Family RVing magazine on Diesel chassis maintenance. I would check it out. I’m a little confused however as to what they are calling the fuel water separator, and which one is the primary filter? When I bought my filters they call both of the them fuel water separators. I was under the assumption the one with the plastic bowl is the primary filter. The other with the sensor plug on the bottom was the secondary filter. Again in the filter description the are both called out as fuel water filters?

[tmw188]

Originally Posted by tmw188

So I did my first fuel filter change without pre filling them, I did the dry install method and it worked out. I wanted to do this while not being on the side of the rd trying it for the first time. So here’s my question. I noticed some small black chips in the primary filter bowl. Is it possible it could be PCs of fuel hose? I plan on looking at them closer tomorrow after I pick them out and lay them on a paper towel.

So an update on this. The chunks just seem to be sediment. I strained them out onto a paper towel and they were easily compressed between my thumb and finger and turned into dust basically. This is a little kit I put together for filter changes. Set the filter into the strainer and let the fuel drop into the container and repeat as needed. If fuel is good put it back into the tank. ATTACH]366911[/ATTACH]

[Ray,IN]

This might explain the sediment you found: https://criticalfueltech.com/faq.html

[tmw188]

That’s a long read but good. This seemed more like small dirty grease chunks that you could scrape off your engine? I didn’t take any pictures unfortunately I usually take pictures of everything.

[96 Wideglide]

Your secondary filter should be FF****.

Any filter that's FS****, is a water separating filter. On your Cummins, your going to want a 5micron secondary filter.

[tmw188]

Both fuel filters shown above are my filters and has FS on them and are both different. Both are called out as fuel water separator, that was my question. It’s obvious the one with the sensor built in is the water sensor and the other has the plastic bowl on the bottom that I’m calling the primary filter. In that write up I mentioned above they call out the primary filter as the the fuel/ water filter. Just a little confusion in my mind.

[wolfe10]

Yes, primary fuel filter is the first one the fuel get to from the tank. It has a courser filter media-- typically between 10 and 30 micron and also serves as water separator duty. I am a big fan of the clear bowl variety, as you can see at a glance if there is water or dirt in it.


The secondary fuel filter is finer-- typically between 2 and 5 micron (engine manufacturer specs how fine it needs to be and varies by engine and which fuel system it has.

[96 Wideglide]

Does your primary water separating filter with the clear bowl have the plug on the bottom for your water sensor to plug into?

[tmw188]

Originally Posted by 96 Wideglide

Does your primary water separating filter with the clear bowl have the plug on the bottom for your water sensor to plug into?

No it doesn’t that is on the second filter I show in post 2.
This is not a big deal I think I got the clarity I wanted. They both have some water collection capability the clear bowl filter is primary the one with the sensor is secondary.

[96 Wideglide]

Looks like a previous owner wanted a separator with the clear bowl, so then they installed a second separating filter on to satisfy the water sensor wiring.

Not going to hurt anything, but I'd make sure that secondary filters down to 5micron.

[tmw188]

The secondary is a 10 micron. This is a quote from old thread below.

At the last fuel filter change that was made at a service shop, they put a 2 micron filter on my 2002 ISC -- 350 HP Cummins engine. I have a two filter set up on my coach. The first filter was a 10 micron and the service shop put a 2 micron filter as the second filter. I started to experience a "studdering" from the engine when I put it under load and started researching and finally talked with Cummins. They said "never put a 2 micron filter on my engine -- it will starve it for fuel !" They told me that the two filters I should be using would both be 10 micron filters. I changed out the filters to two FleetGuard filters (one being the FS1022 mentioned above) and the other is another number FleetGuard (but it is also a 10 micron filter with the water sensor mounted on it). The engine now runs like a new engine and does not have any problems under load. In Service bulletins put out by Cummins they state (for my engine) to never use a filter less than 10 microns. Just thought I would throw this out as my experience with the smaller micron filters.

[wolfe10]

Originally Posted by tmw188

This is a quote from old thread.

At the last fuel filter change that was made at a service shop, they put a 2 micron filter on my 2002 ISC -- 350 HP Cummins engine. I have a two filter set up on my coach. The first filter was a 10 micron and the service shop put a 2 micron filter as the second filter. I started to experience a "studdering" from the engine when I put it under load and started researching and finally talked with Cummins. They said "never put a 2 micron filter on my engine -- it will starve it for fuel !" They told me that the two filters I should be using would both be 10 micron filters. I changed out the filters to two FleetGuard filters (one being the FS1022 mentioned above) and the other is another number FleetGuard (but it is also a 10 micron filter with the water sensor mounted on it). The engine now runs like a new engine and does not have any problems under load. In Service bulletins put out by Cummins they state (for my engine) to never use a filter less than 10 microns. Just thought I would throw this out as my experience with the smaller micron filters.

Sorry, but makes NO SENSE to have a 10 micron primary and a 10 micron secondary. The primary will catch everything and the secondary will "go along for the ride".


Please do confirm that 10 micron IS the correct final/secondary filter element-- many are 5 micron.


And, if 10 micron is the correct secondary, go with a 25-30 micron primary.

[jacwjames]

I looked in my manual, which lists the fuel filters, and both of mine were spec'd at 10 Micron.



I may look at going with a finer filter on the secondary since I've installed a FASS pump that has it's own filter but pushed fuel back to the secondary. I removed the original primary filter.