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Topic: Proper procedure to drain water from fuel filters (Read 1168 times) previous topic - next topic

Proper procedure to drain water from fuel filters

Good evening everyone,
What is the proper way to drain water from the fuel filters?
I think I have two in the engine compartment,
There is one at the back of the coach on the right side and another under the coach also on the right side.

I think there are also two filters for the generator accessible from the drivers side forward compartment.

Thanks
Frank & Daisy
NO LONGER  "looking for the perfect Foretravel
36' or less non slide preferred."  She has been found and is ours.
2003 U320 36' non slide  Unit 6103
Cummins ISM 450
Allison 4000MH

Re: Proper procedure to drain water from fuel filters

Reply #1 –
The filter in the front compartment is for the aqua hot and there should be a filter for the generator located to the rear and outside of the generator box.
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins

Re: Proper procedure to drain water from fuel filters

Reply #2 –
Lt,  Open the drain on the water separating fuel filter and catch the draing fuel in a clear container, clear glass or clear plastic cup.  After draining 1/2 to 1 cup, stop the drain.  Then examine the clear cup to see if there is a line between water on the bottom and fuel on top.  If no line, test to see if all is fuel or water.  If all fuel, you are good to go and all is well.  If all water keep draing till fuel comes out.

Most of the time, you get fuel only.

When I flew Cessna planes, drained each fuel tank before each flight.  Only once did I get water, it was all water, so no line.  But did not look right.  So drained a second time, got a line with water on bottom and fuel on top,  Drained a third time, all fuel and a good flight.  The planes had a special drain cup in each one.

Hope this helps
Rudy Legett
2003 U320 4010 ISM 450 hp
2001 U320 4220 ISM 450 hp
1995 U320 M11 400 hp
1990 Granvilla 300 hp 3208T
Aqua Hot Service Houston and Southeast Texas

Re: Proper procedure to drain water from fuel filters

Reply #3 –
Yup, you are not draining a particular volume.  If draining an ounce or two into a clear container shows only clear diesel, close it, you are done!

Both contaminants-- water and dirt are heavier than diesel and will be at the bottom of the filter where the drain is located.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Proper procedure to drain water from fuel filters

Reply #4 –
You may have to let some air in somewhere to get anything to run out.

Re: Proper procedure to drain water from fuel filters

Reply #5 –
On my 1996 U320, the water/fuel separator is mounted on the frame behind the rear passenger tires. When the fuel level in the fuel tank is low (less than half), air will suck into the separator when the drain valve is opened. Air in the separator is not a good thing, so I often check for a line on the clear bowl attached to the bottom of the separator (indicating water) but will only attempt to drain water when the fuel tank is above 3/4 or when parked on a fairly steep uphill (puts fuel level above separator).
Wyatt
96 U320 40 WTFE, build 4943
84 Toyota Supra towd
2015 Jeep Wrangler towd
Victoria, BC, Canada

Re: Proper procedure to drain water from fuel filters

Reply #6 –
Quote from: P. Wyatt Sabourin –
When the fuel level in the fuel tank is low (less than half), air will suck into the separator when the drain valve is opened.

This is true of any of the fuel filters/ models.  If the level of the fuel in the tank is below the level of the filter drain, it will "siphon" fuel back to the tank rather than draining out the filter. If above, fuel will run out the filter drain.

This is affected by: amount in the tank, installed level of the filter, as well as whether nose is higher or lower than the back. 
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Proper procedure to drain water from fuel filters

Reply #7 –
so will air getting into the filter affect anything as stated above?
do I need to loosen the fuel cap to let air in?
Frank & Daisy
NO LONGER  "looking for the perfect Foretravel
36' or less non slide preferred."  She has been found and is ours.
2003 U320 36' non slide  Unit 6103
Cummins ISM 450
Allison 4000MH

Re: Proper procedure to drain water from fuel filters

Reply #8 –
Quote from: Lt403 –
so will air getting into the filter affect anything as stated above?
do I need to loosen the fuel cap to let air in?
It should not be necessary to loosen a fuel cap because the fuel tank is vented.

Fuel tank venting question. ???
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"It goes without saying..."

Re: Proper procedure to drain water from fuel filters

Reply #9 –
Letting air into the filter will create a stumble the next time the engine is started.  Just don't drain too much, and be prepared to rev the engine on start-up until you clear the stumble.
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Proper procedure to drain water from fuel filters

Reply #10 –
If I suspect that there is air inside the fuel separator, I will suck it out rather than dealing with the engine stumbling.
I have a hand air pump hose (used to pump up bicycles tires) and attach the open end to a hand vacuum pump. Attach hose to schrader valve on top of the fuel separator housing and pump until diesel appears. I built this simple device when I replaced the OEM fuel/water separator.
Wyatt
96 U320 40 WTFE, build 4943
84 Toyota Supra towd
2015 Jeep Wrangler towd
Victoria, BC, Canada