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I wasn't questioning if it existed or anything just curious what it said and their reasoning.
yea, i figured that.
we question because we want to learn.
otherwise we would just be making uneducated guesses at ways to properly repair things.
if i remember correctly, the reason for the TSB was that the one way valve could fail allowing air into the fuel filter which allowed the filter to back drain to the tank causing a hard start condition.
by capping off the port and line, you eliminated an air intrusion point to the filter housing.
It's a spring check valve to keep back pressure on filter to bleed air out. There's a flow restriction orifice in the end of the barb to limit flow. The check is designed to prevent flow from the return line into it. The spring is around 1psi at my best guess. Its similar to a ball point pen spring. The check ball appears to be PVDF/Kynar, the seat in the filter head is ground into the aluminum housing.
I'm not going to pull the one on my parts truck, there's no way this valve could be assembled backwards because the spring would pass through the check ball seat and into the filter head.
the ones on my trucks were opposite of that. i wonder if someone took it apart and put it back together backwards?
Unless they used and oversized spring it would have fit through the ball check seat and gone into filter. There's no seat ground into the brass fitting either.
I would just pull your fittings and look at them to see what they look like. I dont see how the injector caps would have enough pressure to overcome the incoming filter pressure with an open return line leading to the tank.
easiest way to test is to remove the fuel filter before starting cold. if it is full, the fuel system is fine.
So the filter was full, but that **** was stuck on there, don't know when it was last changed, what's the best filter for these? Price isn't that big of an issue my dad always changes his every third oil change or right before a long trip and never had problems. I have access to to wix, and a Donaldson dealer if they make one that fits
i use the napa 3417 filter, it is made by wix if i remember correctly.
it is also a one piece with water drain, less chance for leaks and easier to put on.