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Fix your fuel leak from filter drain valve

108189 Views 66 Replies 52 Participants Last post by  Catch-All
I imagine that you guys down here in the basement are having troubles with fuel leaks like the superduty crowd is. I just posted some photos that may help out with this.

Here's some pix of a 94-97 van filter drain valve.

Auto part

Auto part Hardware accessory


Personal protective equipment

Personal protective equipment

Or you can go to my album that has more pix (hit the max of 5 inserted in a post) and some notes about disassembling the valve.

94-97 Fuel Drain Valve - TheDieselStop.Com Photo Hosting
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Braggi nailed it. With the 99-2003.5 F-250 or F-350 7.3L engine, it's almost always the Fuel/ Drain Valve.

Plan A - Buy & install a new valve assembly from Ford dealer (approx $65) or from NAPA (approx $46) or from
Plan B - Buy the three o-rings from DieselOrings for $6 + shipping. If you are in a hurry, you can buy two assorted size Viton (brown color) o-ring kits from Advance Auto for $7.99 per kit. Between the two kits, you will get the two o-rings of one size and one o-ring of smaller size that you need. has three grades of o-ring kits available - BEST Fluorosilicone (blue), BETTER brown Viton, GOOD Viton


DieselOrings has a comprehensive parts list that covers most of the common repair and maintenance problems you will encounter with the 7.3L engine.

My 2000 F-250 Lariat crewcab was leaking diesel intermittently for the last couple years. Even though I'd used Superchips to chip the truck several years ago, I began noticing the smell of raw diesel right after I'd changed out the fuel/ water separator filter. As part of the process, you have to cycle the fuel drain valve open to drain all the fuel (and any water) out of the fuel bowl. I think that's when the o-rings developed a slow leak.

I did a lot of research on the internets. Sites like this and YouTube helped me diagnose and narrow down the problem. (from DieselTechRon)
this clip is particularly good because he deals with all THREE o-rings. There are two o-rings (see BEFORE pic) that are the same size. There is a smaller, thinner o-ring that is concealed inside the stem. When I dis-assembled the valve I found that the smaller, inner o-ring had been replaced with a cheap, non-fuel resistant rubber o-ring! That's where the leak was.

-one T20 Torx bit $2.49 (get the short one)
-the three o-rings (Advance Auto) $16.00
-36inches high-temp fuel hose 3/8" I.D. (for attaching underneath to bottom end of fuel drain tube)
-one set of three Finger Drivers from Toolworks #TW690 (for tight spaces) available at Advance Auto for $2.99

-without chipping the engine, the 7.3L engine F-250 should be giving you 20 mpg on the highway at 2000 rpm (approx 67-70mph depending on tire size & rear differential gear ratio).
-with the engine chipped for "towing" or economy mode with even a basic chipping module (I used Superchips), you should be getting approx 26-27 mpg highway at 70 mph/ 2000rpm.

I'm not even a Shadetree Mechanic but everything I've read on the internets says that the two main things that can adversely affect economy are a fuel/drain valve leak and a clogged EBPV Exhaust Back-Pressure Valve & Tube.

Last Summer the Fuel/Water Drain Valve was in a temporary non-leaking mode and I did an EBPV Valve Sensor replacement. I also used brake cleaner and a length of thick, ribbed weedwhacker line to ream out and clean out the EBPV tube that runs from the sensor to the exhaust. On a 186 mile trip from Louisiana to Gulf Shores Alabammy I used exactly 7 gallons fuel at 70mph the whole way. I topped off the 30 gl tank before I got on the highway and topped it off again with 7.0 gls in Gulf Shores after stop & go traffice down Rte 59 in summer traffic. That's 26.6 mpg fuel economy without having to deal with that politically-correct Exhaust Fluid BS being shoved down our throats by the Environmental Industry.

Here's the best video clip I saw for dealing with the EBPV issue: (Trey Spooner)
Total Parts:
-Exhaust Back Pressure Valve sensor
-weedwhacker line
-can of Brake Cleaner

I hope all this helps!


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