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Using return fuel line for additional filter?

015point9
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wil440

wil440

Posted
Posted (edited)
2 hours ago, 015point9 said:

Is there any logical reason why I can't install a filter in the return fuel line?   

 

My fuel supply line goes from fuel tank to Airdog (95 or 100?) then directly to VP44 and very happy with the way AD is plumbed and mounted.  

I have done quite a bit of testing on the fuel system on my truck and one thing I noticed is that my idle fuel pressure is around 8 psi with mechanical pump and Cat filters, it does rise rather fast with rpm, anyway I did restrict the return a little to check what would happen to the fuel pressure, it went very high very fast so thats one reason not to put any restriction in the return line, the other is return fuel cools the vp so restrictions wouldn't be good, the other reason not to do it is fuel returning should be very clean if your fuel filters are doing their job, only debris that will ever be in the return line is if the vp or injectors are making metal and you'd know about that rather fast I'd say.

One thing I will add, I have a lot of fuel returning back to tank in the return line even at 8psi

Edited by wil440
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Tractorman

Tractorman

Posted
Posted
6 hours ago, 015point9 said:

Is there any logical reason why I can't install a filter in the return fuel line? 

 

Never restrict fuel return lines or offer a potential fuel restriction such as using a filter in the return line.  Diesel fuel injection pumps / lift pump systems are essentially hydraulic systems.  The rules of fluid power flow and pressure apply to both.  The bulk of the fuel system is plumbed is  a series circuit from the lift pump, through the VP44 injection pump and the return lines.  Any restriction added to the return raises the pressure upstream in order to push the fuel through the line.  Flow is constant and  pressure is accumulative in a series circuit.  You won't see it on a fuel pressure gauge on the lift pump circuit because the gage compares fuel pressure in the line to atmospheric pressure.

 

If a filter on a return line circuit became seriously blocked, fuel lines and components upstream could see pressures higher than they were designed for - such as VP44 pump case, seals, and low pressure return fuel lines.

 

- John

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NIsaacs

NIsaacs

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33 minutes ago, Mopar1973Man said:

Exactly. I would never put a filter in the return line of the fuel system. 

 

Same reason I will not put a filter in the return line of the power steering either. 

 

 

That's apples and oranges. Hydraulic systems all use return filtration. Even your wood splitter. The bypass valve in the filters will save the system from high return pressure.

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