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2014 e250 bluetec
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Discussion Starter · #1 · (Edited)
hi, first time posting here.

i have a 2014 e250 bluetec with 48k miles. while i was driving yesterday, the diesel fuel splashed out from the bottom middle part of the car that made my full tank of fuel nearly emptied in 5 minutes! the check engine light was on and the acceleration couldn't pass 30 mph!

i had done the AEM recall in june 2021, and in august 2021, i accidentally put unleaded gas in this diesel tank, and the dealership had to drop the tank and cleaned everything out (suspension components and blow out all the lines, etc...).

would this fuel splashing be caused by any jobs that were done by the dealership? thanks!

Situation: when i accidentally put unleaded gas into the diesel tank less than a month ago, i didn't turn on the engine, and immediately had it towed to the dealership for repair. however, the towing guy did accidentally turn on the engine for one second and immediately shut it down when he was trying to put the car to neutral for towing...

Update 1: got the diagnosis from the dealership. "Found 2 failing fuel lines going from fuel tank to high pressure pump leaking!" with the unleaded gas be immediately removed and all system cleaned, is it possible for these plastic lines to be damaged like this?

Update 2: the dealership that my car is currently at says they found no causal factor or responsibility on the dealership, who did the repair, for the needed repair!

Update 3: reported to mercedes usa headquarter but the "highest" person i can go replied that since there is nothing hq can do! so it's ok for two fuel lines to break at the same time and possibly caused deadly accident! i told that person that if no one is at fault, then it might be a bigger problem, because it might be a bad design that needs to be recalled to prevent any accidents. but that rep just ignored me! i guess mb owners life don't matter!

Update 4: got the car fixed, hopefully, and the shop foreman stated that there is no sign of damage visually or in the locking function of the plastic lines. there is no sign of damage to the internal seals of the lines and the steel fuel lines. however, the plastic fuel line disconnects within a minute when running the engine! due to there are no visible damages to the plastic line, the shop foreman suspected the incorrect fuel has jeopardized the integrity of the plastic material of the fuel line, causing it to be unable to withstand the operating fuel pressure. does it make any sense at all?! at least it doesn't make sense to me. every time when i asked if there is any possibility that this could be a human error, by previous repair shop, they never gave me an answer and just jump straight to the incorrect fuel. i strongly felt that dealerships are trying to cover for each other... i kept both "failed" plastic fuel lines with me hoping i will be able to investigate further.
 

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I don't know exactly what lines that car uses, or how they connect, but my guess is when they put the lines on they forgot to tighten one or more clamps, fittings or whatever is used, then later it popped off and your pump drained the tank as you described. Usually lines like that will not completely pop off, but instead the pressure will force the line to back until the pressure that forced it off is vented, so there's a good chance the line is still pointed in the right direction and feeding the eng, but at barely any pressure while the rest is dumping all over the ground, which explains the 30mph. If the line has split from old age then it would no doubt start slow and you'd notice the smell and/or puddle where you park. A mech would also notice a bad line, either old or damaged. So basically I blame the mech either way but I'm not buying it leaked due to age, so damage or error, and damage is error so error period.
If you took it to the same dealer that did the cleaning then it's possible they covered up the mistake by claiming the lines were bad. Just my opinion but I don't see how else it could've happened. It's also weird they said two lines were bad. So they forgot two clamps, or said that to sound more convincing that it was due to age?
And no, gas won't hurt the line, at least not any fuel line I'm aware of. If plastic like you said then it's probably Teflon which can not only handle just about anything, it should last decades. If it's Nylon then it'll have a shorter life, but it would still last much longer than yours is old and the mech would notice if it was at risk. For typical older cars I see fuel lines leaking at 15 to 20+ years, and they all weep gas slowly, then a drip, then worse and worse until you notice. Never seen one dump like you said, but I have seen them dump when people forgot to clamp them.
So (imo) splitting, cracking or whatever failure they claim is extremely unlikely. The fact they were in there working those exact lines, then they leaked days later, narrows it down to all but guaranteed they caused it. Imo.
This is one reason I don't let people touch my cars. People make mistakes all the time and I see it at my work all the time. Things that people know how do, yet they manage to do it wrong anyway. Or they think they know how, but don't, which is also very common. I know this because I'm usually the guy they call to figure out what's wrong.
 

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2014 e250 bluetec
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Discussion Starter · #3 ·
I don't know exactly what lines that car uses, or how they connect, but my guess is when they put the lines on they forgot to tighten one or more clamps, fittings or whatever is used, then later it popped off and your pump drained the tank as you described. Usually lines like that will not completely pop off, but instead the pressure will force the line to back until the pressure that forced it off is vented, so there's a good chance the line is still pointed in the right direction and feeding the eng, but at barely any pressure while the rest is dumping all over the ground, which explains the 30mph. If the line has split from old age then it would no doubt start slow and you'd notice the smell and/or puddle where you park. A mech would also notice a bad line, either old or damaged. So basically I blame the mech either way but I'm not buying it leaked due to age, so damage or error, and damage is error so error period.
If you took it to the same dealer that did the cleaning then it's possible they covered up the mistake by claiming the lines were bad. Just my opinion but I don't see how else it could've happened. It's also weird they said two lines were bad. So they forgot two clamps, or said that to sound more convincing that it was due to age?
And no, gas won't hurt the line, at least not any fuel line I'm aware of. If plastic like you said then it's probably Teflon which can not only handle just about anything, it should last decades. If it's Nylon then it'll have a shorter life, but it would still last much longer than yours is old and the mech would notice if it was at risk. For typical older cars I see fuel lines leaking at 15 to 20+ years, and they all weep gas slowly, then a drip, then worse and worse until you notice. Never seen one dump like you said, but I have seen them dump when people forgot to clamp them.
So (imo) splitting, cracking or whatever failure they claim is extremely unlikely. The fact they were in there working those exact lines, then they leaked days later, narrows it down to all but guaranteed they caused it. Imo.
This is one reason I don't let people touch my cars. People make mistakes all the time and I see it at my work all the time. Things that people know how do, yet they manage to do it wrong anyway. Or they think they know how, but don't, which is also very common. I know this because I'm usually the guy they call to figure out what's wrong.
thank you for your input! your input makes much more sense than what the dealership's shop foreman has said that there is no sign of damage visually to the plastic lines and locking function, but it just won't stay connected!?! and he ruled out every possibility except the incorrect fuel! they refused to factor in any possibility of human error! they are treating customers like 3 year old kids. oh, i have included updates on my original post as well. i wish you were the one who diagnosed my car for this problem. cheers!
 
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