Originally Posted by TheMilnes
Update: We called Freightliner, and they said there's no pressure at that point. It's suction. He then asked if both filters were from the same batch? We think so. Our next door neighbor is a mechanic for the county. He's never had a fuel filter split. He's wondering if we may be over-tightning the filter. Current filter is from a different batch. Fingers crossed.
What they should have stated is that there "should" be no pressure at the filter. It is not possible for the filter to rupture at zero to low pressure, I suspect the racor filter housing could handle up to ~100psi (although not necessarily rated for 100psi). In any case, the problem is that the fuel pressure from the high pressure pump to the injectors, or perhaps more likely the fuel "gear" pump above the filter is pressurizing the filter when it should be bypassing the filter and passing the excess pressure to the fuel return line. (or a high pressure filter is used)
I want to also make sure you are aware that while diesel is not easy to light with a match, a diesel mist under high pressure is extremely flammable and even without a spark, enough heat can ignite it. I would be very hesitant to simply change the filter again and wait and see if the problem reoccurs. If it does light up on fire, you will need a fairly large extinguisher if you even catch it in time.
I have worked on all types of diesel (and gasoline) engines over the years (not as a career) and familiar with the older systems, this is the system I think your may be and if check out page 2 it shows the gear pump and a series of solenoids over and above the filter, this "integrated fuel system module" (IFSM) is computer controlled and what I suspect is that one or more of the fuel return passages are plugged (perhaps partially) or one or more of the solenoids is malfunctioning... or the filter really is supposed to be a high pressure filter and isn't as noted below.
In any case, you should double check and see if this PDF is a match for your cummins fuel system and if so (or even if not so) I would highly suggest getting everything checked out in a diesel shop before something major occurs (fire), unless you are mechanical and can get the tools and a service manual. (I would try to get a filter from Cummins first though and try to compare it to the racor).
If you look at pages 13~14, they specifically state that the filter is a "Pressure Fuel Filter" so with that in mind, I suppose it is certainly possible that the genuine cummins filter may be designed to handle a lot more pressure than the Racor even if they are a match for the size. I couldn't find a service manual for the IFSM system, but I suspect all the answers could be found in one.
One other point, on page 5, this pdf states "The 380 psi high pressure regulator, installed in the IFSM between the gear pump and the filter, is a
safety valve to prevent damage in case of a stuck fuel shutoff valve or other blockage in the fuel lines after the gear pump."
this statement to me implies that the filter may actually have a lot of pressure on it ~380 psi.
btw, not sure why the link says "recall" in the name of the file, I didn't see anything in the pdf about a recall.
The fuel system developed for the Signature and ISX engine was constructed to deliver precise injected fuel quantities with precise injection timing at high injection pressures. The system consists of six high-pressure unit injectors and an integrated fuel system module (IFSM) containing actuators that provide various fuel pressure pulse widths to individually control injection quantity and injection timing, a pump and regulator for fuel supply pressure, a 10 micron pressure side filter, and various sensors for system monitoring. The system is controlled by an advanced electronic control module (ECM), which makes fueling and timing decisions based on temperature, barometric air pressure, boost pressure, exhaust gas pressure and throttle position.