Community Forums

greatlakes · 05-05-2014, 07:21 AM

So last year when I did my annual maint /filter changing I replaced my fuel filter and pre filled it thinking it was the right thing to do. It was a Napa filter.
This year I have an actual oe filter and noticed printing on the filter that says for isc engines do not pre fill filter.
So I did not and cycled the key a few times to cycle the fuel pump before starting. Fitted it up and it stalled after a few seconds. I felt like crap.
Turned it over again and after cranking for 15 seconds it fired up again and is running fine.
So obviously the isc engines have a way to bleed off any air?

Skip426 · 05-05-2014, 09:27 AM

Most newer Cummins engines have an electric lift pump to deliver fuel from the tank to the high pressure injector pump, and the high pressure " Common Rail " Cummins system will bleed any air out.
Filling a new fuel filter, prior to install ; can introduce contaminants, from your fuel container along with the unfiltered fuel ; into the high pressure pump & Injectors , so always follow manufacturers instructions on fuel & oil filter installation.

Muddypaws · 05-05-2014, 09:36 AM

I made a filter filler out of a small funnel and an inline filter. Fuel goes through the inline filter and in the input side of the new filter. It's worked well a couple of times.

But next time I'm planning on installing a mechanical lift pump.

jmoffat · 05-05-2014, 09:40 AM

different engine so maybe differant answer but I have a CAT C9 and I replaced the fuel filter last year and did not prefill the filter per instructions in owners manual I do not have a manual pump and as far as I know I do not have a electric pump to prime the filter. Bottom line could not get the engine to start had to call a technician to help and he took off the fuel filter filled it up with deisel and after a few tries the engine started. Am getting a manual hand pump installed next month at a Cat dealer Just saying

Jim

lanerd · 05-05-2014, 09:48 AM

If you fill the fuel filter by pouring the fuel into the small holes around the circumference of the filter, the fuel will then pass through the filtering mesh and fill the center of the filter. You should never, never pour unfiltered fuel into the center of the filter to fill it. Sometimes the filter will come with a plug for the center hole....use it to keep the new fuel from getting into the center.

This also holds true for the oil filter too!

Ron

Vanwill · 05-05-2014, 09:53 AM

Much debated subject--prefilling filters on ISC and later engines. True, the electric lift pump should eliminate the need for prefilling. If you do not prefill on the earlier engines, you will have a helluva mess on your hands. On the ISC and later, if you do not prefill, you will only have a helluva mess on rare occasions.

I think the Cummins position is understandable. They want to guard against warranty expense due to someone inexpertly prefilling the filters. I'm sure there are even those who have prefilled using the center hole. But regardless the vintage of the engine, there will always be competent mechanics who will choose to carefully and correctly prefill the filters. I am one of those. I have a plug for the center port. Frankly, even if you pour contaminated fuel in the OUTER part of the filter, you will have no problem. Pour it in the center hole, and if it's the primary filter, you'll probably be OK. Pour contaminated fuel into the center of the secondary filter and you may engender a very, very expensive repair.

The great majority of the time, if you change your filters by the Cummins-approved method on your ISC and later engine, you will experience only a minor hiccup and have to restart the engine a few times.

So, I think the choice is up to the individual, based on his abilities and experience. I would never consider arguing for either method.

Van W 2000 Dynasty 36 (ISC-350), pulling one Harley
Eastern NC

96 Wideglide · 05-05-2014, 07:35 PM

Quote:

Originally Posted by lanerd

If you fill the fuel filter by pouring the fuel into the small holes around the circumference of the filter, the fuel will then pass through the filtering mesh and fill the center of the filter. You should never, never pour unfiltered fuel into the center of the filter to fill it. Sometimes the filter will come with a plug for the center hole....use it to keep the new fuel from getting into the center.

This also holds true for the oil filter too!

Ron

This is the method I used, and the motor started up like I'd never touched it.
I'll add one thing..... I changed one filter at a time, starting with the separater (primary), then started and let the motor run a few minutes before changing the secondary.

Mike Canter · 05-05-2014, 07:49 PM

Rob, the way your motor started then stalled then started after 15 seconds is perfectly normal and expected. Most secondary fuel filters use a 10 micron screen because one piece of dirt almost that small will block and injector. That is small enough that you would not see it in the fuel that you are pouring into that filter. I think you did a great job and if I was you I would keep doing it that way and not risk messing up an injector.

Muddypaws · 05-05-2014, 07:59 PM

I built a funnel/filter with an inline fuel filter and carefully allowed it to drain into the outer holes in the filters.

However! Walking through HER motorhome with a filled fuel filter even when it's in a sealed plastic bag is a terrifying experience! Before I do it again I'm going to get the mechanical pump that goes on top of the filter housing. When I looked for them a few months ago they were about $50 and looked simple to install.

powerboatr · 05-05-2014, 08:53 PM

my cummins fleetguard filters have a removable plug in the center so you can fill them, without worrying about pouring it in the center hole.(make sure it get pulled before installation)
this year i did the pre fill and it made a world of difference on the first start up routine

96 Wideglide · 05-05-2014, 09:03 PM

5 micron secondary on a newer Cummins.
If you have a steady hand, good container your pouring from, it's pretty easy to pre-fill the filters thru the outside small holes.

greatlakes · 05-06-2014, 06:21 AM

Quote:

Originally Posted by lanerd

This also holds true for the oil filter too!

Ron

I typically pre fill oil filters but I've never worried about putting it in the center hole. Basically because the oil is coming from a clean plastic container that I just opened. Not a fuel can that can gather particles. Plus its typically dumped into the top of the motor unfiltered and isn't as delicate as the fuel system.
I think its more important to wipe down the area around the fill cap before opening. I've watched people knock crud on top if the engine right into the valve cover.
Either way I suspect most guys here take better care when changing filters than most shops would.