Primary fuel fiter change procedure?

[Robby W.]

Much to my surprise I didn't fine much information on changing fuel/water separator filters on motor homes, mostly info on to, prefill, or, not to prefill the new filter. I'll follow the Cummins 5.9 ISB manual and replace dry and then bump the starter 3-4 times to prime.

Should I open the valve on the bottom of the old filter and drain it before removal? Should I do this till the fuel stops? Will the fuel stop? I'd kind of like to know what to expect before I removal.

Thanks in advance for any advice,

Robby
Iowa

[palehorse89]

Originally Posted by Robby W.

Much to my surprise I didn't fine much information on changing fuel/water separator filters on motor homes, mostly info on to, prefill, or, not to prefill the new filter. I'll follow the Cummins 5.9 ISB manual and replace dry and then bump the starter 3-4 times to prime.

Should I open the valve on the bottom of the old filter and drain it before removal? Should I do this till the fuel stops? Will the fuel stop? I'd kind of like to know what to expect before I removal.

Thanks in advance for any advice,

Robby
Iowa

Hi Robby, From your manual, your ISB has a lift pump(fuel) to prime and feed the high pressure fuel pump just like the ISC engine. Everyone on here does it a bit different, some even fill the new filter with transmission fluid........
On my ISC, I open the bottom drain, let the biggest part of the fuel drain out, mine does not stop, as there is a lot of fuel in the lines clear to the front.......so after the biggest majority is drained out, spin it off, I pre-fill my new one(starts easier) before the reinstall. I have tryed it both ways and find the pre-fill is easier and faster when starting the engine. If you choose to install the new filter dry, you can do so, when ready to start the engine, "Cycle" the ignition key on and off 12-15 times leaving it "on" for a minute or two each time, doing this is letting the lift pump pump the fuel into the new filter and purge the air out of the fuel system. Good luck, both ways work......it up to you.........I am sure others will chime in also to help ya out with this question.
Some reading for you to look at https://www.google.com/search?q=filt...+site:irv2.com

[jacwjames]

I have both a primary and secondary filter. I usually drain the filters so that I don't spill fuel while changing.

I change one at a time. I will drain and remove the old filter, install the new filter and turn the key on ~30 seconds (I do not bump the starter) then off & repeat this 3-4 times until I hear the fuel pump stop. I then start the engine and let it run for a little while. I then change the 2nd filter.

I do not prefill the filters. I bought my RV used but I did get all the manuals which included a Cummins Operators Manual. If you read the manual it will explain the correct procedure which specifies to not to prefill. This is probably to prevent contamination.

As you said there are different opinions on this but I follow the manual.

Good Luck

[Robby W.]

Thank you so much Jim and PaleHourse.

I feel a lot better now. I still haven't located the secondary filter yet, I don't even know what it looks like, line filter, spin on canister or element in a bowl.

Robby
Iowa