Re-occurring fuel issue. need help please

[HardRockNM]

If your filters are losing prime you will either have a blockage or you are sucking in air somewhere. It sounds like you have eliminated a blockage so that leaves sucking in air. Whichever filter that is losing prime the air leak will be in the line before the filter that loses prime. I would carefully check your lines and every place they make a connection. It is possible to have a leak in the suction side of the fuel system and not have fuel leaking.

One of the mines I work at has a CAT 980G with this problem; it's got a pinhole letting air in, so needs to be primed at the beginning of the day and whenever the machine is shut down for more than around five minutes. The dealership mechanics can't find the leak, so they just deal with it.

 

[thepumpguysc]

Sorry everyone.. I'm alittle late to this party..
As u probably know, when u pulled the filter down & heard a rush of air, its vacuum.. the supply pump on the engine/inj. pump IS PULLING fuel.. but none available which means either the LONG RUBBER HOSE is collapsed or theres a rag in the tank..
I wish I had a nickle for every hose I replaced on a TD466.. I have a tail lite bulb that i rigged up on a stick w 2 long leads that i clip on the truck batteries.. to look into fuel tanks.. works like a dream..
Most of the DT's I've worked on have a hidden water separator up behind the passenger side wheel well..

 

[old-iron-habit]

On my old 1974 International 8V71 Detroit on my slasher truck I had similar issues, Turned out the fuel hose from the tank to the fuel pump was flattened out where it laid over the frame, Just closed up from it own weight laying on the frame. New hose and ran like new again.

 

[Coaldust]

Like PumpguySC said, this inlet filter screen often gets overlooked.

 

[tech1234]

UPDATE: solved!

It was a fuel treatment cap (the little penny sized ones that pop off, not the screw ones) someone must have dropped in the tank at some point. It was getting sucked up and blocking the fuel flow. Truck is back to running well! Thanks for the help guys

 

[Nige]

Kudos for posting the update, but I wonder if it was really necessary to start two threads regarding the same issue..?