Join Date: Mar 2019
Location: Bay Area, CA
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2018 F350 Fuel Tank Drain The Easy Way
Hi all - Recently had an experience with F350 SD KR that I wanted to share. Im sure that there are many posts on draining the fuel tank, but I couldnt find anything on 2018. What prompted this whole thing was I was looking on how to energize the fuel pump relay to pump contaminated fuel (diesel and gasoline) out of the tank. After some looking I read that the fuel pump relay was now part of the fuse box or some such nonsense, so that was a no go. So beings as i did not want to drop the tank, which had 55 gal in it, had to look for another way. I will note that the truck had been started and ran a short minute with said fuel, then shut down when it was realized what had happened.
I realize there are many out there who are used to performing stuff like this so I apologize for the lengthy post. Just want to make sure I explain well. Also, please excuse the crude drawing, as I could not take photos when all this was happening.
What I used:
2 people if possible
12 gauge stranded wire (2 lengths 6-10 ft long)
2 female crimp connectors
2 alligator type clamps
1/2" dia. heater hose about 6 feet
1/2" dia. copper tubing 2-1/2" long (any smooth metal fitting that same size would work)
12 V car battery
1/4" or 5/16" dia. rubber hose about 12" long to fit over fuel rail
Several fuel can or buckets
Please see crude drawing.
From drivers side you can reach up under the bed and unplug the connector on top of fuel tank.
Crimp the connectors onto 12 gauge wire on one end of wires, the alligator clips on the other end. Make sure your female crimp connectors are the correct size for the connections at #3  in picture.
Connect your wires to #3 & #4.
Under the hood -undo the clip and unhook the line on the fuel filter that is closest to the firewall. This is the in from tank line. Slide the 1/2" dia heater hose over the copper fitting and insert copper fitting into the line you disconnected. Make sure to put the other end in container your draining into.
Hook the alligator clamps to the battery (doesnt matter which way. ) The pump should start running. If nothing is coming out of hose, just switch the leads on battery and it should start working.
Continue draining the tank til empty. Of course disconnect your battery leads when your switching containers.
**Note: since this was diesel contaminated with gasoline, I replaced the fuel/water separator filter under the truck by the tank and the fuel filter under the hood. Cost is around $100. Both are easy to change out.
Now would be the time to change these filters out. If your not changing filters, then go ahead and put some fresh diesel in tank.
Hook up your leads to battery again and pump some fresh fuel thru the tank line. You can disconnect your hose at this point and hook it back up to the fuel filter.
On the fuel rail, disconnect the black hose with the white connector (this is the return line) and attach the 1/4" or 5/16" rubber hose (whichever one fits) and hook up your battery leads again to make sure that whatever contaminated fuel might be in there gets pumped out. 10-15 secs or until decent stream comes out. Make sure other end is in container.
Hook the hose back on fuel rail, reconnect your fuel pump connector under the truck and you should be good to go.
Truck started perfect and runs great. Hope you dont ever have to drain your tank, but if you do, I found this to be really easy compared to dropping the tank.
"Nothing solves a problem like an aluminum bat and a wood chipper."-Author Unk
2018 F350 SD KING RANCH
1990 RAM 12 VALVE CUMMINS