Why my Davco Fuel Pro is draining below collar and doesn't fill?

Ok, So here's the deal. My Davco does not fill up, and the level will actually drop to below the collar then rise to an inch above the next day and vice versa,but never more. Things I have done so far,

-Fuel pressure test, result OK

-Changed filter and the spring at the top of the housing

-replaced the check ball and spring at fuel inlet

-replaced gaskets and checked for leaks, none found

The last filter was in there for more than 80,000 miles and the paper was starting to break down.

The truck starts and runs fine and does not seem to have any loss of prime. Fuel is not going into the coolant. Nor is coolant making it into the Davco.

Answer this question I have this problem too

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9 Answers

There has to be air getting in somewhere.

How does it start? Do you have to crank on it?

I had that problem once and all mine was the O ring must have had a crimp on it somewhere. I changed out the O rings and it was fine. I could also see bubbles when the engine was running.

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The truck starts fine, no problems. There is no air bubbles, and no leaks.

by Ross Farrant

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Might be the check return valve that isn't working properly.

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http://www.davco.com/diagnostics.html here is the Davco website help page

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I have consulted the davco website. The only symptom that is like what I'm going through is th air getting into the system. However I do not have any air bubbles coming up in the housing. Fuel level was below the collar again this morning.

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the glass will get fuller as the filter gets dirty. The filter gets dirty or plugged from the bottom up. So the dirtier the filter, the higher the glass will stay full.

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I know how it is supposed to work....

by Ross Farrant

well then if you know so &@!$ much about it why are you on here asking?

by Mark French

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was at mats,was talking to the davco rep, he mentioned the exact problem you are having he claims that if you put the wrong micron filter in, the bowl may never fill up,check to see if you have the right filter.

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Thanks Tony, I will double check the filter number.

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I had a similar problem on mine... I was rather embarrassed to admit it, but I put the large 'o' ring in the wrong place. I had it between the screw on ring and the housing. It should have been between the metal, and the housing to make a good seal. It was allowing air in, and would never stay up with fuel, but would run fine. Let us know if that helps. Good luck!

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Ross, I just went through about the same thing. I did have bubbles in my dome. I checked and replaced the o-rings and filter, all of the fuel lines. After doing all of this it was still getting bubbles, so I ran a line directly from the tank from the fill hole on the tank. No bubbles or loss of prime. I then isolated each tank individually without gout through the tee. The problem turned out to be in the left tank. I haven't had it fixed yet but I have isolated that tank and do not have to deal with the problem until I get home. I hope this helps, good luck.

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Ross Farrant will be eternally grateful.

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