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Toribk 09-27-2019 08:04 AM

I'm glad to see Diesel Dan came out to lend his experience as this helps everyone.

Here are a few things I've learned over the years that might help a few others that feel a bit of trepidation changing their own fuel filters......and please, feel free to comment or add if you like.

I always start off by placing a clear plastic drop cloth under the engine to protect the floor from fuel. I then take a large disposable aluminum turkey pan and fill it with a bag of kitty litter as a cheap absorbant for fuel seepage during the filter exchanges. I wear my nitrile gloves as well.

I have the Cummins ISC 8.3L engine that has the primary filter (fuel/water seperator) and the secondary filter mounted directly to the engine.

The FW seperator is gravity fed, so it is best to do your filter changes when your fuel gauge is just above your 1/4 tank mark. Also, remove your gas cap to take any residual pressure out of the fuel delivery system. This tip I originally got from Freightliner in Gaffney.

Now, I have the Alliance (Freightliner private label) brand filter and separate detachable bowl that attaches to the bottom of the filter that has a short pigtail harness for the "water-in-fuel" detection sensor. So, since it is screwed together and installed as one unit, I bought a second bowl and pigtail connection to make the exchange much easier.

I assemble my new filter and bowl together, pre-fill it (yes...I'm a pre-fill advocate) with fresh fuel through the outer holes of the filter casing with the center hole plugged, and then set it aside until I'm ready to do the exchange. I then loosen the installed FW seperator with my NAPA heavy-duty (webbing) strap wrench with both a 3/8 and 1/2 drive fitting and then swap the two filters as quick as possible by hand. The turkey tray and kitty litter catch the majority of fuel during the exchange. I tighten the new filter by hand as tight as I can get it and then just a quarter turn more with the strap wrench.

Now that the FW seperator is done, I put my gas cap back on, cycle my key off and on (without starting the engine) about three times to get the fuel pump cycling and make certain the FW seperator gets topped off with fuel and then start the engine. I have found that both pre-filling the filters AND changing one filter at a time, with a start-up in between,
virtually eliminates starting problems. Just my experience and observations at both Cummins and Freightliner service centers I have visited....though unlike the DIY'r, they tend to do BOTH filters at once to save time.

Once I have verified the FW seperator is fine and there is no fuel leaking, I shut off the engine and in the same fashion, remove and replace my secondary (engine) Fleetguard (Cummins) fuel filter. The secondary filter has both an outside and CENTER rubber gasket, so make certain they both come off and are in place when the new (pre-filled) filter is installed. Hand tighten, then just a quarter turn more with the strap wrench to fully seat the gasket (s).

Repeat the starting procedure cycling the key 3 times on and off and start her up. Check for any fuel leaks.

Another thing I use is "3 in1 Oil" to coat my gaskets on the both the filters and the fuel bowl O-ring during assembly and installation. Just use a tiny drop on your fingertip to rub on each gasket so there is nothing excessive, yet enough lubricant for the gasket to turn and compress firmly without binding.

I know this was long winded, but it may help and instill confidence in others that want to save the time and cost of running the coach to a service center for a relatively simple maintenance procedure.

FLSteve 11-01-2019 08:30 PM


Originally Posted by dvmweb (Post 4965540)
Well, Diesel Dan came out and had a look. He showed me a priming pump/bulb on top of the water separating filter. He pumped it about 20 times, went in and cranked the engine about 1/2 minute and it fired right up. Whew!

dvmweb thanks for this post. I was in the same boat as you were and after reading it I went back out and had the engine running in about a minute. I guess I was just not cranking it long enough as I was afraid I might overload the starter. It started after about 10 - 15 seconds.


imnprsd 11-05-2019 12:14 AM

I have an electric fuel pump so I don't have to "hand pump," but I hear those who do say it's easier to prime if you only replace one filter at a time... start the engine... then replace the other filter. I think would start with the secondary filter first if you have 2 filters, but it may not matter. (Let us know if it does.)

I don't have personal experiences on this recommendation so maybe someone can back me up on this recommendation or say it's just an old mechanic's tale.

There are a lot of things you can do to service your RV and keep it running. Don't forget to search on YouTube also. The best way to learn is to watch a video.

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