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Old 01-28-2021, 02:56 PM   #1
Join Date: Jan 2021
Posts: 96
Fuel Filter Fuel/Water Seperator

Trying to swap out my Fuel Filter and Water/Fuel separators.
When I pull the plug on the separator the suction continually pulls fuel from the tank and never empties. I have searched all over and do not see a shutoff to stop flow and maintain suction.
ISC 6.7
Winnebago Journey

Any advice?

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Old 01-28-2021, 03:07 PM   #2
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You will need to install a diesel-compatible ball valve on the inlet to your primary fuel filter. Not aware of any OE installations that came with one.

You are correct, if level of fuel in tank is above that of the fuel filter, fuel WILL run out.

But, that actually, is better than the alternative-- if level of fuel in tank is lower, fuel will drain back to the tank, leaving you with 30+ feet of AIR in the fuel line that will need to be purged!

Until you install the ball valve, just have a bucket under the filter, new filter with O rings on it ready to go and all tools at hand. Be sure to remove old O rings.
Brett Wolfe
Ex: 2003 Alpine 38FDDS. Ex: 1997 Safari Sahara. Ex: 1993 Foretravel U240
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Old 01-28-2021, 03:09 PM   #3
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I was afraid that was the solution.....thanks
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Old 01-30-2021, 02:21 AM   #4
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Any part of the fuel line from tank to primary water separator made from “rubber”? I have used fuel line crimp pliers or needle nose vise grips with a couple of plastic/rubber hose covers slipped over the teeth to squeeze hoses and block fuel flow.
Towr: 2007 Country Coach Allure 470 - 37 Sunset Bay Cummins 400 ISL, Coach #31563
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Old 01-30-2021, 05:36 AM   #5
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I've removed the line from the in side of the filter housing and zip tied it up higher than tank level to stop the flow. Much better than a diesel bath!
The Castles
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Old 02-05-2021, 10:31 AM   #6
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I took the head unit from the filter/separator down to the local Goodyear Rubber Products and bought some ball valves and had them install them with appropriate elbows, straight pipes, etc - one on in and one on out:


Works great.
Rick and Larrie Dee
1997 40' Newmar London Aire DP CTA 8.3 (Mechanical) 325 Spartan MM
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fuel, water

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