Maxforce 13 fuel issues

Its also strange, I have the housing bolts loose and a clear line coming out. I can see some air and if I shake the housing it gets much worse. I have tried everything to try to get good seals on the housing. I have replaced the bottom seals and many o-rings. There is one oiring on the bottom that I acnnot find a good match for. Davco does not sell or even list it as an item.

 

I don't see anything in the tanks and I blew air down through the pickup tubes. It all looks clean. I have taken all of the fuel lines apart and replaced the orings. Also when I ran a big clear line from the housing to the inside of a tank it did the same thing.

 

I am trying to avoid purchaseing a new unit when i don't need it if something else is the problem. Just like what you are explaining.

 

Can the restriction be after the housing and before the pump? Perhaps the clear line going from the housing to the primer bowl is to small. Or could it be after the primer bowl ?

 

"I have tried everything to try to get good seals on the housing. I have replaced the bottom seals and many o-rings."
"I can see some air and if I shake the housing it gets much worse." This is indicative of a loose fuel line fitting or one that needs to be sealed.
What did you try? Did you remove anything threaded into the Davco, remove it and clean the male and female threads, then use tape and reinstall? Check for cracks, even use a magnifying glass. Use a small pick and brake clean to clean the threads if necessary. Also makes a difference how the tape is wrapped. Tape gets wrapped clockwise if looking at from the threaded end.
What Davco do you have? Navistar should be a Davco 483 or 488. The link for the parts list is below.
"I have replaced the bottom seals and many o-rings" Not sure what you are talking about as the whole unit only has 2 o-rings and some seals for the drain valve.
Service Parts Information - Product Support (davco.com)

 

Look at this diagram, There is an o-ring on the bottom of the big hex bolt on the very bottom the the unit.
https://www.davco.com/media/davco/forms/F3086.pdf

 

Fuel Pro 382 Coolant Heated Bottom Plate

 

Every fuel line fitting that goes on the unit whether it is for an International or Freightliner or Pete, ect. has a boss type o-ring that fits in a grove cut in the filter housing but they will not sell an o-ring.

 

It is a 382, I think it is an o-ring seal but I have tried 3 seperate units (not new) and they all do the exact same thing. Different filters, different bowls, ect. I used to be a pretty good trouble shooter, I know I am missing something, that is why I am reaching out for help.