According to this, the filter could also have come in a replacement fuel pump.

 

saw that too... will ask the customer when he comes back in, but the pump looks pretty weathered... it certainly hasn't been replaced recently.

Water separator drain plug did come out... they are often seized into the cover very badly in my area. Got a fair bit of water when I drained it.

I wish I knew about the FF markings the first time I changed my own filter... I would have paid more attention to what they look like!

 

Is the new filter marked in a similar way? What was the fuel pressure when you checked it? I don't run a factory pump so I haven't seen a factory filter in a LONG time.

 

New filter (OEM Ford) had different numbers stamped on it (see pic below)

Fuel pressure sat around 50 psi at idle and fluctuated wildly while driving but my gauge has no damping... I use a filter cap with a tap feeding fuel pressure directly to a pressure gauge. This isn't the perfect setup, because it tests pressure before the second filter, but it's good enough for most testing and diagnostic work. The needle was bouncing a lot while driving, but I would say it was swinging between 30psi and 50psi under WOT. Not good for injectors! The Ford dealership already put in 4 new injectors for this guy (there were just throwing parts at it, obviously).

Here is the old and new filter side by side. They are also different heights, and with different sealing mechanisms on the bottom... really has me wondering about the history of this filter that was originally installed.

 

The new filter is the updated one but I don't know exactly when it came out. Been a while though. The old filter is horrible. I'm sure you're going to check the pressure after the filter change, but you might also want to look into doing a blue spring upgrade on the regulator. It can't hurt anything.

FWIW--my fuel pressure never jumped around idling or driving with a manual gauge. I think this is a good case for the blue spring upgrade also.

 

absolutely do the blue spring! I keep a couple of the blue spring kits on the shelf at all times... and I'm constantly ordering more... cheap, quick and protects $2500 worth of fuel injectors!

I haven't checked fuel pressure yet... just got the filters in last night... this truck needs a couple of front wheel bearings also, but I will be checking the fuel pressure again to see if the filters were causing the fluctuations in pressure.

 

I believe they came up with the new primary fuel filter with the introduction of the 6.4 model. I like the new ones cos they seat and seal better.

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