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Mark Rinker
04-24-2009, 05:55
I always assumed that the 'Change Fuel Filter' message was simply based on a preset mileage counter, but an experience yesterday leaves me wondering if it isn't 'smarter' - i.e. reading a drop in fuel rail pressure. In the morning, the message came up at startup. Hadn't seen it before, but it made me consider the mileage on that particular filter, which was approaching 15K.

By that afternoon, immediatly after a re-fill in southern Illinois, I got an SES light and limp. Read the code with the Predator, sure enough low fuel rail pressure. Reset the code and resumed a safe highway speed with the oversize boat, until a suitable exit was found. After changing the filter, the message alert has disappeared, without any pedal-dance to reset the indicator.

Maybe this thing is smarter that I thought...?

Also - I carry a strap wrench, but never need it. Mechanix Gloves and the red aluminum tool for removing the WIF sensor is all thats needed, if you only twist them hand tight. A good trick learned from JK. When re-priming, I use the rounded end of the red tool into the dished top of the primer button, gaining some advantage by using both hands to drive the button down firmly until fuel is seen at the breather. Saves on sore fingers. I can usually do a filter with zero fuel spillage under the hood, and be back running in the truck in about 10 minutes - a little longer if its -10 below...cussing takes time.

More Power
04-24-2009, 10:21
What's your owner's manual say about changing the fuel filter and the 'Change Fuel Filter' message?

It would make sense to include a 'Change Fuel Filter' message into the programming whenever a fuel-rail pressure related DTC is detected, though I don't know how the ECM would know you changed the fuel filter.... ;)

Jim

Mark Rinker
04-25-2009, 06:23
Thats an easy one, Jim!

If the message was based on the fuel rail pressure falling outside a preset range, or experiencing a % drop from its previous nominal pressure, all the ECM would need to know is the rail pressure was now back to normal = don't display the 'CHANGE FUEL FILTER' message at startup.

Just speculation, but its what I experienced. Maybe resetting the SES with the Predator also reset the Fuel Filter Life counter? That would explain things, but I know that using the Predator to clear codes does NOT reset the Oil Life counter. I'll look at the OM today and see what it says. (My guess is it will be predictably vague, and written by someone that has never driven a Duramax. :)

I'd like to get to the bottom of this one, if they have built some 'smarts' into this message, I'll follow its guidance. Otherwise I'll stick with the ~15K mile change intervals.

Kennedy
04-25-2009, 20:06
Mark,

Are you sure it was change fuel filter and not water in fuel? I've heard of the WIF light on high restriction.

Mark Rinker
04-26-2009, 05:48
Yeah, it was the change message, not the water message.

I have never seen a WIF message on a Duramax...? Seems to me you'd have to have ALOT of water in the filter before it would float that sensor! Had a 3208 Cat in a Ford L8000 that lit up regularly.

Mark Rinker
04-28-2009, 11:33
Okay, okay so this morning I go to start the truck, and the CHANGE FUEL FILTER message illuminates again.

WTF?

Back to thinking its just mileage based...but why so random, once the threshold is met? Hmmm...