Paccar water seperator

[Bigcam3cummins]

Has anyone had problems with the paccar fuel filter not staying full. I have gone though the fuel system from the filter back to the tanks looking for a restriction or something should I be looking some else?

[Waterloo]

I don't think they are supposed to stay full during normal operation. I have the Davco unit on mine, when the filter is changed it may have 1/2 inch of fuel showing through the plastic dome, and as the filter ages the fuel level rises. Personally, I just drain the water off periodically and change at every other service. I have never seen mine full other than the time it hit -30 on the thermometer...

[scottydogtruck]

Two culprits on this.....

1. Check the large O-ring that goes on the plastic housing after you replace the filter...if it doesn't seal properly, it will not fill up. The bowl is supposed to be full, and if it isn't, it will cause you to not have enough fuel going to the pump and have acceleration problems.

2. Check to see if the pressure relief fitting on top of the unit is closed up. if it isn't, will cause it not to fill.

Also check to see if your electric pump is working properly...small round unit between the frame and the engine, below your high pressure return filter.

[scottydogtruck]

Here's the two culprits...

[Optimanzltd]

(05-08-2016 )Bigcam3cummins Wrote:  Has anyone had problems with the paccar fuel filter not staying full. I have gone though the fuel system from the filter back to the tanks looking for a restriction or something should I be looking some else?

Hi, I used to sell those davco filters for a living. They are not supposed to be full.
The idea is that the fuel level shows how dirty the filter is, low level and the paper is doing its job and is nice and clean.
As the fuel filters through the paper it slowly " blocks' the paper and the fuel level rises slightly looking for cleaner easier flowing paper to go through.
When it reaches a high level it is time to change the element.
There is usually a black line on the top part saying maximum level, or change filter when it reaches this level.
The way the element is designed allows you to change it and fill the bowl with fuel from the top and you never get dirty fuel on the clean side of the filter.
Most outfits should be able to sell you the correct spanner for undoing the bowl and the top nut, a 2 in one tool .
With older type screw on filters people used to fill them with fuel before fitting them and you get dirty fuel on the clean side.

[Waterloo]

(05-08-2016 )Optimanzltd Wrote:  

(05-08-2016 )Bigcam3cummins Wrote:  Has anyone had problems with the paccar fuel filter not staying full. I have gone though the fuel system from the filter back to the tanks looking for a restriction or something should I be looking some else?

Hi, I used to sell those davco filters for a living. They are not supposed to be full.
The idea is that the fuel level shows how dirty the filter is, low level and the paper is doing its job and is nice and clean.
As the fuel filters through the paper it slowly " blocks' the paper and the fuel level rises slightly looking for cleaner easier flowing paper to go through.
When it reaches a high level it is time to change the element.
There is usually a black line on the top part saying maximum level, or change filter when it reaches this level.
The way the element is designed allows you to change it and fill the bowl with fuel from the top and you never get dirty fuel on the clean side of the filter.
Most outfits should be able to sell you the correct spanner for undoing the bowl and the top nut, a 2 in one tool .
With older type screw on filters people used to fill them with fuel before fitting them and you get dirty fuel on the clean side.

That is the way I have always understood how these work. Is the Paccar unit somehow different than the Davco unit because of its mounting position? Seems they would work on the same principal, when the bowl is full, change filter? Myself I never wait that long and change out every other service.

[overshot]

I think the paccar filter work in the opposite way. When the fuel level in the bowl gets low thats when you change it. But , I change it every time I do the PM.

[overshot]

(05-08-2016 )overshot Wrote:  I think the paccar filter work in the opposite way. When the fuel level in the bowl gets low thats when you change it. But , I change it every time I do the PM.

Well, I am wrong. Apparently the bowl stays full. You are supposed to change it at certain interval.
Or when you have a loss of power, oops that's way to late.

[Bigcam3cummins]

My understanding is the filter should be full, fuel gets sucked from the top so if it the fuel is down in the bowl would it not be sucking some air... Could it be the check valve by the primer pump? If it was the priming pump itself is it not support to run for so many seconds and shut off the check valve will close allowing the gear pump to bypass the primer pump.