Why RAM Cummins 2500 fill tube leaks diesel when fueling

Why diesel fuel leaks down the back of the fill tube onto the ground when topping off fuel tanks.

[@Zukgod1]

Very helpful, thank you. Historically when adding fuel additive I've used a long funnel and didn't have an issue. This morning I couldn't find the longer funnel so I grabbed one with a stubby neck and started dumping it in. It went all over the driveway. After watching your video I ran out with a long screwdriver and flipped the second flap (that I didn't know was there) and what hadn't leaked out dropped in the tank.

[@Dunne1025]

Today added injector cleaner and freaked out when I saw it dripping from this exact spot! Just had a FASS system installed and thought it was from that? Excellent video and explaining! I have learned so much from your videos and have the same truck! I’ve done my own oil changes , prior fuel filters and diff fluid change all from your videos! Saved me a shit ton of $$$. Thanks for taking the time to do these videos!

[@getonss]

Great explanation! Thanks for sharing. I’ve got some diesel coming out of the little hole. I thought it was coming out of the relieve valve.

[@clockworkbike]

Great video! I appreciate you explaining the intricacies of these trucks.

[@supporterofsanity]

Yep gotta bury that nozzle in there or your gonna get spillage. Good camera work!

[@shiznit93274]

Yay. First comment. I found out the hard way about the spillage when topping off. I no longer top it off high. Let it stop and then give it one more click about 15 seconds later. No more spills and I am sure I have enough fuel to get where I am going. Great video as always. I enjoy watching every one you post.

[@MarionBlair]

Yes, that's the key, don't bring the fuel up close to the green neck.

[@LWFG1]

Thank you. You’re a genius. I got fuel trapped in this space. Leaked all over the ground. Complained to the dealer. I brought it in. They supposedly replaced the fuel filler neck and said it was cracked. Defective. Now, when filling with fuel, I make sure to put the fuel nozzle all the way in and stop filling after the first click off. Dealers are stupid.

[@MarionBlair]

Yea, it's definitely a point of confusion and even the damn dealer can explain such a simple thing. They should know better.

[@francissullivan6400]

Great video..I bought my 2014 last year with 38k on the odo..and it came with that cheap red plastic plug..I said W.T.F is this ..WHERE IS THE CAP..and explained the newer models dont have them..I would not take ownership of my truck until he located one..now I hold onto that plastic fill plug like it was made of gold..GREAT VIDEOZ. keep them coming from a GOD FEARING PATRIOT stuck in COMMUNIST NEW YORK

[@frankmjr6571]

Found that out adding fuel injector cleaner, started spilling on the ground. Found out Dodge added that feature to prevent people from adding DEF fluid to the fuel tank. A small amount will probably make it into the tank, but it will prevent a few gallons from entering.

[@BlackAtomAnt]

Same thing happened to me.

[@leonardrice2830]

This did help, thx! I had a habit of keeping my 2018 Ram 3500 CTD full to tippy top. No issue at first, but then got the leaking problem at subsequent fill ups. I took a clean section of flexible aluminum tubing and screwdriver guided by flashlight and verified that second flapper/valve. I think over filing causes fuel to accumulate between the external and second valve. Add cap, & some fuel just sits there between inner & outer valve. I dried up everything underneath & gonna run w/o cap, see what happens.🤔

[@2009reezen]

genos garage makes a great full cap for our trucks. very worth it in my opinion.

[@MarionBlair]

Yea, I got one of their originals. Not as nice as the latest ones but it keeps water out.

[@allincamo]

Marion, you need to invest in one of them magnetic diesel fuel caps. EBAY. sells then 20-25 bucks. I have one and glad I do , prevent water and dirt that gets in behind the door.

[@kixforrest2358]

I have learned after the fuel nozzle shuts off automatically the first time: I get my $$ amount to the next dollar & stop filling. No more pumping until the tank is completely full.

[@miket7756]

Great video I'm sure I did the same thing by overfilling. Problem now is 3 days have past and I ran the truck down to 3/4 but I still have diesel dripping very slow leaving a stain on my driveway. Is it possible its caught in that area and dripping out very very slowly? Any way to clear it or just wait a few more days for it to empty out? Thank you 🙏

[@anthonycameron3783]

I have a 2019 2500 cummins and went to fill it up the other day and i guess someone forgot to let the nozzle sit there for a while cause when i went to put it in fuel spilt out and a little went into the cap before the nozzle did noticed a little drops comin from under the door area and kinda glanced up there noticed the 2019s i guess they added a little tube from that little hole u pointed out now

[@AD-zy5gr]

Thank you sir!

[@leonardrice2830]

Update. Since last post, I've gone by the car wash, soap pressure washed the inside of panel where diesel & DEF goes. I've filled tank several times, making sure nozzle is pushed all the way in, thus engaging first & second check valve. 🤔 Guess what? No leaks! 😄 No dripping diesel!

[@gunfreak565]

The check valve below the trap door lid is to prevent fuel from escaping in the event of a rollover.

[@MarionBlair]

Good point, thanks

[@ronmoore3987]

Yes very good, who knew--!

[@skipnick]

already made the mistake of overfilling and made a mess. but at least the fuel didnt shoot out the top! perhaps another reason the overflow is there; if the fuel did reach the top of the filler neck, where debris may be sticking, it would cause the debris to flow into the tank more easily? just a thought, thanks for the video!

[@goducgo]

How do you fix it. Resting the fuel nozzle on it will break it eventually.

[@marxvadar2614]

Thank you!!!!!!

[@historygradstu]

Hi Marion, I just discovered leaking fuel too ( 2017 2500 6.7) Probably overfilled. The filler neck tube inside the fender well looked the same as yours did. I also noticed fuel between the first and second check valve as shown in your video. I depressed the second check valve and the remaining fuel between the two check valves of course went down the filler tube. But heres the rub: I was down to 3/4 of a tank and I still saw fuel leaking on the concrete in the same area ( small amount, maybe 2 ounces)...would the fuel trapped between these two check valves be the culprit? Or is the little drain slot after the second check valve? Thanks if you can help

[@MarionBlair]

It's the Overflow the little drain slot, once it starts leaking it does it for a long time because there's some foam stuff that absorbs a lot of diesel and it will finally quit, more than likely unless you have another problem which I don't think you do

[@MarionBlair]

The leaking for days is a very common complaint when that happens. I wouldn't worry about it. I think it will go away. If you want to expedite it, you can get under the fuel door with some rags and you'll probably see it's dripped on the hoses, fender etc...

[@historygradstu]

@@MarionBlair Thanks Marion I do appreciate it...it does make a mess. I wont overfill from now on and will look between those two check valves too. I bought one of those filler caps too off of ebay...kinda didnt like that plastic red stopper that came with it. Oh, that steering wheel tie rod recall thing...I probably wont do anything on that, I checked it, its good and tight and still has the paint markings from the factory showing everything is still the same...I will still keep an eye on it. Now that grid heater bolt getting sucked into the intake kinda has my attention though!. thanks again Marion!

[@MarionBlair]

@@historygradstu yes no doubt the killer grid heater issue is there but I also think it's rare. I don't question that it happens but a friend I have at the dealership has never heard of it in 28 years. I know the dealership information is a pretty low bar but all he has seen is solenoid failures. But I'm not dismissing it, and I will keep an eye on it.

[@danlora1478]

This is the only source for my issue. Thank you. I was worried I would have to replace my fuel filler neck due to a leak. I guess I don't. What I did develope was a crack on the outer green lip that the nozzle sits on when filling. Put some super in that crack(going to get the right adhesive next week) and I wrapped a #28 clamp around to give it a little strength when the refilling. What adhesive can I use to fix that crack? Thank you for the info.

[@MarionBlair]

One of the Permatex silicon gasket maker products would probably do it but I like your idea of a hose clamp. That'll probably keep the crack from spreading.

[@danlora1478]

@@MarionBlair I read somewhere someone had a crack and someone suggested a clamp. So I went with it. Thx for the Permatex suggestion.

[@tomwilson7806]

Hey Marion A little off the topic but the manual for my 2014 Ram diesel says to use straight diesel not biodiesel. I can't find it. What do you say? Thanks Tom

[@MarionBlair]

I say it all has 10 percent.

[@4wdiesels]

My 2015 Ram ecodiesel did this bad if I topped off. It had the same filler neck. My 2019 Ram 2500 Cummins doesn't do this anymore. They redesigned it. It is still capless but has a better vent. By the way, mopar sells caps for both styles old & new. Different part # beginning with 2019s. I added it to both trucks.

[@Reeltinyphish]

I use the big rig pumps because I have a 42’ toy hauler. I spill diesel all over the place. No matter how fast I let the flow go, it spills. Does the nozzle not go deep enough?

[@MarionBlair]

I have not had a problem with the big rig pumps for the most part but I don't keep them wide open when I'm pumping

[@HonkeyKongH]

Hey Bud, have you heard of the nozzles not clicking off at all? The only way I know the truck is full is if I hear it start to leak out. It’s a 2014, 2500 with the 6.7 (obviously). But it either does the thing where it clicks every two seconds or it doesn’t click off at all. And I end up making a mess at the local WaWa. Any tips?

[@MarionBlair]

No, the main issue that I've heard of and had personally was the thing clicking off prematurely. If I wiggle it around and get it to the right side of the fill hole,, that seems to help

[@HonkeyKongH]

Marion Blair I’ll Have to see if Maybee I can shove her down a little further and wiggle to the right, appreciate it

[@motodude93]

Could this be why I smell diesel inside the cab? I have a 2015 ram 3500 that I just noticed starting to smell like diesel or perhaps an exhaust leak inside the cab. Seems to be worse when I turn on the heater my thoughts are it's an exhaust leak but then I came across this video. Any thoughts?

[@MarionBlair]

Don't think it would smell in the cab but maybe. Any leaks under the truck when parked??

[@jacobdiaz6432]

7-11-19 Have you had any challenges filling your tank where it won’t except any fuel. It happened to me last night where it would only take like 80 since it looks like that bowl that’s in there is not allowing fuel to flow through. Just wondering

[@MarionBlair]

Yes, in fact I have an issue yesterday. Some pump some more sensitive than others. You have to get the nozzle in as far as it will go and then wiggle it around from side to side until you find which point it will take the fuel better, it's the vent line that's being blocked by the nozzle and causing it to click off. Unfortunately it's normal, just have to fight it

[@jacobdiaz6432]

Thank you for responding that ball in there seems to be blocking the flow it doesn’t go down.

[@MarionBlair]

You have to push past that second check valve (what looks like a ball) otherwise, it won't take any fuel. Push the nozzle in hard all the way till all of the nozzle is in. It won't hurt anything.

[@5cent27]

Experiencing this with my ecodiesel today haha. Guess I over filled the tank. 🤦‍♂️

[@chrisveach2105]

I would assume that the little drops of fuel coming off the bottom of the fill tube is from my over fill. Over filled it on Thursday and still getting some dripping off the fill tube almost a week later.

[@MarionBlair]

Yes, it takes a while to stop.

[@floydwilliams3321]

I actually think it might be for water to get out cause if you add some fuel additive Without using a funnel it just runs out that little hole good video buddy

[@MarionBlair]

I agree, that a good thought, you don't want water collecting in there and running into the diesel/ DEF tank.

[@700TwinPolaris]

Hi. My 2nd check valve broke off and it is sitting in the fuel filler neck making it hard to fill up. Do I need that second check valve or can I just get rid of it completely? Also do you have a video on how to take apart the fuel filler neck so I can get that piece out of there? Thank you!

[@MarionBlair]

By second check valve, do you mean the top one? Neither one of them are necessary for the operation of the engine. The lower one is probably there to keep diesel from spilling out in case of a roll over. The top one does nothing, IMO. Otherwise, probably not needed. The tank is vented from a small line off the tank. Keep a cap on it to keep dirt out. I don't have a video on taking the neck out, sorry. I'd try to fish it out with a grab.

[@700TwinPolaris]

Yes I have tried but unfortunately the flapper is to big to come out of the top hole. It’s just a nuisance when trying to fill the tank up.

[@700TwinPolaris]

By second valve I’m actually meaning the 2nd flapper thing

[@airlope22]

What is that blue tab to the right for?

[@Reeltinyphish]

DEF

[@garydevore3330]

If the full runs out can the vent filter get clogged?

[@MarionBlair]

No it won’t

[@hardtruth2039]

I ordered the diesel and pdf caps before I picked up my 2018 Ram 2500 Cummins. Made no sense to me why the cheap SOB’s didn’t put them on the truck from the factory.

[@petersannicolas8949]

Very hard to add diesel additive need a long enough funnel to put your fuel additive

[@BackriverRebel]

This is the one of two things that I dislike about my ram. No diesel fuel cap, and no locking fuel lid. What is up with that?

[@MarionBlair]

Yea, they cheeped out. Should have retooled and put a big door when they went to DEF injection.

[@ki6lkp]

I just don't learn! Shortly after buying this truck (6 years ago), I foolishly topped off the tank, WRONG, what a mess! With that, I printed a label to remind myself "Do not top off!". Well, I did it again today. Even at today's $6.50/gal, I added about 85 cents and made a big big mess. Moral of the story..., when the *#@_* thing clicks that it's full, hang it up. I say this over and over, "When it smells like cologne, leave it alone!".

[@floydwilliams3321]

Nonetheless it’s a piss poor design but they do offer a new aftermarket That goes in it that’s magnetized I got one the other day it was 45 bucks off of Amazon

[@MarionBlair]

Agree

[@DarrenMoore71]

I just bought a new RAM 2021 and got that cheap red thin plastic cap, I was like, what the hell is this. I just paid 90K for a truck and this is what came on it! BS. I did not know it was capless at the time. So the factory wants to ship it to the dealer with that plastic cap cover on it but then they expect you to remove it and use it capless??? The factory must not have faith in the capless system, if so why are the shipping it to the dealer with cap on it? Just recently, when I was fueling the truck, I placed it on my on bed and the damn wind blew it behind the truck cab and the bed and I couldn't get it out. Then I had to add DEF and just as the DEF tank fueled up. About a tablespoon of DEF splashed over into the diesel closure flap and I started freaking out because the DEF started slowing draining and disappear before I could get a rag and soak it up! I thought it was going into my fuel tank. I was so pissed off, and thinking why in the hell would they design something like this. In my opinion, there should be a cap on the diesel because you don't want to risk ANY getting into these tanks. I went and bought some water remover and pour it in the tank. I was in the middle of a long road trip on my way back home when this happened pulling my 5th wheel and drove 500 miles in one day, no issues. So assume everything should be fine. So ANY (ie water or DEF) liquid that sits on top of your fuel flap first closure will LEAK down into the filler tube, I hope to GOD that is draining on the ground somewhere. If it's just sitting between the filler tube then the next time you fuel up. You're draining that into your tank. The next time you fuel up add a little diesel on top of the first closure flap and you'll see what I am talking about, it will slow drain.

[@MarionBlair]

Agree, instead of making the fuel door bigger they cheeped out and put a fill tube that was so close and small, no cap would fit. Ford handled it the right way.

[@bayonne]

I hate this capless fill tube, It’s a real pain in the ass to add fuel additive. I have to stick a long skinny funnel down in the hole to open the second flap or the additive will not make it into the tank. Also, that green plastic top is weak, I have read of several cracking with rough handling of the fuel nozzle. It’s a shitty design.

[@MarionBlair]

I've noticed that also. I suspect it all because RAM didn't want to enlarge the door and do it properly. The new Ford Super duties have a huge door with with both DEF and Fuel with a stardust cap.

[@evilone6785]

bayonne I have found if you get the fill tube from a ford you can put in there and add additives and no mess. Got mine from my mustang

[@MarionBlair]

Me too, dumbest thing RAM every did. They didn't want to enlarge the door and retool so they cheeped out and stuffed it all in the old compartment. A diesel tank needs a cap, period and does not need check valves.