DEF Fill Issue
Thread Starter
|
Laughing Gas
Joined: Feb 2011
Posts: 991
Likes: 6
From: Newberry Springs, CA
DEF Fill Issue
Greetings all,
Had an interesting thing happen tonight and need some help. I got the "100 miles to go " warning yesterday. I picked up 2, 2 1/2 gallon boxes of Blue DEF, knowing that since it was THAT low, it would likely take both. Well, I uncorked the first box and started to fill the tank, it got to about 2 gallons and then started puking back out through the tank fill. I stopped, let it settle down and started to fill it again, it immediately started backing up again.
Not sure WTF is going on, but I know for a fact that 2 gallons will not fill that tank, anyone else come across this?
Thanks in advance,
Had an interesting thing happen tonight and need some help. I got the "100 miles to go " warning yesterday. I picked up 2, 2 1/2 gallon boxes of Blue DEF, knowing that since it was THAT low, it would likely take both. Well, I uncorked the first box and started to fill the tank, it got to about 2 gallons and then started puking back out through the tank fill. I stopped, let it settle down and started to fill it again, it immediately started backing up again.
Not sure WTF is going on, but I know for a fact that 2 gallons will not fill that tank, anyone else come across this?
Thanks in advance,
FTE Legend
Joined: Mar 2017
Posts: 31,969
Likes: 9,197
From: Western NY
Greetings all,
Had an interesting thing happen tonight and need some help. I got the "100 miles to go " warning yesterday. I picked up 2, 2 1/2 gallon boxes of Blue DEF, knowing that since it was THAT low, it would likely take both. Well, I uncorked the first box and started to fill the tank, it got to about 2 gallons and then started puking back out through the tank fill. I stopped, let it settle down and started to fill it again, it immediately started backing up again.
Not sure WTF is going on, but I know for a fact that 2 gallons will not fill that tank, anyone else come across this?
Thanks in advance,
Had an interesting thing happen tonight and need some help. I got the "100 miles to go " warning yesterday. I picked up 2, 2 1/2 gallon boxes of Blue DEF, knowing that since it was THAT low, it would likely take both. Well, I uncorked the first box and started to fill the tank, it got to about 2 gallons and then started puking back out through the tank fill. I stopped, let it settle down and started to fill it again, it immediately started backing up again.
Not sure WTF is going on, but I know for a fact that 2 gallons will not fill that tank, anyone else come across this?
Thanks in advance,
I replaced my DEF pump and sending unit this fall in my driveway. Its a doable jobnon the ground but a PITA... There's a sleeve in there that goes inside the tank first before the sending unit gets placed inside the tank. I wonder if there's an issue in there for some unknown reason...
Standby for pics.
These are after I pressure washed the top of the DEF tank... and I was installing the new sleeve and sending unit/heater.
You can see the bend in the fill hose from it hanging over. I would check to make sure your hose is not twisted up for some reason. Also do you use a factory fill hose that has a vent hose in it?
New sleeve and sending unit going in.
New sleeve in
Sending unit in with sleeve, top of sending unit shown there before being placed in the sleeve in tank.
Installing tank back in. Note the fill hose. Check for that. Have you done any work to it lately?
Last edited by Overkill2; Dec 19, 2025 at 09:23 AM. Reason: Add to post -- pics
Thread Starter
|
Laughing Gas
Joined: Feb 2011
Posts: 991
Likes: 6
From: Newberry Springs, CA
Thanks for the input all, much appreciated.
I can generally get about 6500 miles out of a full tank, but I tow occasionally and drive fast. I only had a half a tank this last time and got 3300 miles out of it.
I did notice some crystallization around the fill pipe, that may be an issue. They replaced my tank heater about 2 years ago, I'd like to think they may have cleaned the tank when they did, but I could be wrong.
Gonna try the cleaner route first, if that doesn't work I may have to go Overkill's route.
Will update when I know something, thanks again!
I can generally get about 6500 miles out of a full tank, but I tow occasionally and drive fast. I only had a half a tank this last time and got 3300 miles out of it.
I did notice some crystallization around the fill pipe, that may be an issue. They replaced my tank heater about 2 years ago, I'd like to think they may have cleaned the tank when they did, but I could be wrong.
Gonna try the cleaner route first, if that doesn't work I may have to go Overkill's route.
Will update when I know something, thanks again!
FTE Legend
Joined: Mar 2017
Posts: 31,969
Likes: 9,197
From: Western NY
Thanks for the input all, much appreciated.
I can generally get about 6500 miles out of a full tank, but I tow occasionally and drive fast. I only had a half a tank this last time and got 3300 miles out of it.
I did notice some crystallization around the fill pipe, that may be an issue. They replaced my tank heater about 2 years ago, I'd like to think they may have cleaned the tank when they did, but I could be wrong.
Gonna try the cleaner route first, if that doesn't work I may have to go Overkill's route.
Will update when I know something, thanks again!
I can generally get about 6500 miles out of a full tank, but I tow occasionally and drive fast. I only had a half a tank this last time and got 3300 miles out of it.
I did notice some crystallization around the fill pipe, that may be an issue. They replaced my tank heater about 2 years ago, I'd like to think they may have cleaned the tank when they did, but I could be wrong.
Gonna try the cleaner route first, if that doesn't work I may have to go Overkill's route.
Will update when I know something, thanks again!
Trending Topics
Tuned
Joined: Aug 2024
Posts: 409
Likes: 139
Yours sounds different, maybe a crystallization issue, but I've noticed the factory DEF gauge is somewhat inconsistent. I've had mine puke out DEF twice now after I try adding a whole jug. Super annoying. I usually refill it when it drops to the 60-65% range. Seems like 63% can mean different things on different days cause one time it'll take the whole jug and another time it'll spill out.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 6 Best Deals Available on New Fords & Lincolns Right Now
Brett Foote
This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level
Verdad Gallardo
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
FTE Legend
Joined: Mar 2017
Posts: 31,969
Likes: 9,197
From: Western NY
My buddy just had a 2016 6.7 in the shop where the DEF tank read okay on the gauges but it was at the 500 mile warning. They contacted me via text because they knew I did the DEF pump/sending unit job this year. Plus they asked about the harness behind the fuel tank where mine was opened and one of the fuel sending unit wires was shorting on the fuel tank.
They dropped the fuel tank to inspect the harness and found nothing wrong. They dropped the DEF tank to check the wiring and connectors -- all good. That particular truck was sprayed with anti-rust stuff, do not know what, but my buddy said they cleaned the tank vent fitting because I'd assume it had dirt collected on it from the spray job, they re-installed the tank and it took 5 gallons because the tank was empty when they dropped it. All good now...
As to the OP, I wonder if this possibly could be a venting issue or if there is crystallization in the DEF fill hose or the fitting there.
My buddy stated for his 19 GMC K2500 6.6 Duramax, he used the Rislone additive and said the crystals he had at the DEF fill port just melted away when he put it in his DEF tank. FYI.
They dropped the fuel tank to inspect the harness and found nothing wrong. They dropped the DEF tank to check the wiring and connectors -- all good. That particular truck was sprayed with anti-rust stuff, do not know what, but my buddy said they cleaned the tank vent fitting because I'd assume it had dirt collected on it from the spray job, they re-installed the tank and it took 5 gallons because the tank was empty when they dropped it. All good now...
As to the OP, I wonder if this possibly could be a venting issue or if there is crystallization in the DEF fill hose or the fitting there.
My buddy stated for his 19 GMC K2500 6.6 Duramax, he used the Rislone additive and said the crystals he had at the DEF fill port just melted away when he put it in his DEF tank. FYI.
Thread
Thread Starter
Forum
Replies
Last Post