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Just got this 2017 450,
I was driving 80mph in the middle of Nevada and suddenly lost power,had to pull over and stop,car would crank and not start fuel gauge at 40% of tank,i thought timing was screwed up ,called towing and and told the guy lets try adding couple gallons before we go to a shop and the car started like nothing happened,i had this happen on old audi s8 d2 so im familiar with scenario,im guessing some pipe disconnected or something in the tank,i added 16.5 gallons of fuel before pump cut off,26.5 i think its total capacity
Sounds like it has a "saddle tank" (a tank with two chambers) and the transfer mechanism isn't working. Sorry, I have nothing more specific, even though I own one...
I have a ‘13 GL350. It does have a ‘saddle’ tank that sits above and on each side of drive shaft. There are also two fuel pumps, one on each side but only one feeds the engine. That would relegate the other to transferring the fuel as you stated. You should be able to determine if the pumps are working with diagnostic software but that might require the dealership or hopefully a good Indy you may know. Access to the pumps to replace are not fun as the exhaust and drivetrain need to be dropped in order to drop the tank to access the motors which are mounted into the top of the tanks. (Don’t ask how I know this). I assume yours may have the same setup.
I had something like this happen to me on the older ML500. It ended up being the fuel pump malfunctioning when it happened to me. Once a new fuel pump was put in, the problem went away for me.
1000 miles later in Nebraska my fuel gauge stoped working and now i got check engine light,is the fuel sender part of the fuel pump?
car still drives perfectly normal
Seller helping you out lol did that ever work
so i got low fuel pressure,i am pretty sure cleaning the filter will help but well see,not ready yet to dump few grands on this,i can drive like this and refuel every 300 miles which i would usually do
Bmw dealer in st louis that sold me 2013 gl back in 2020 with a coolant leak that could cost me new engine but i cought it on time also gave me 3000 mile warranty and he never picked up the phone nor answered email
Since you are willing to live with this, at least for a while, and absent access to the Benz diagnostic software (which I think can activate the fuel pumps and/or give more detailed codes) perhaps you can try one or both of the following to confirm gas is on one side of the saddle tank and not transferring to the other:
1) under the car, at the rear doors, you may be able to see the tank on each side of the drive shaft (hard plastic). When you know you are running low, see if you can tap each side with a wrench, or your knuckles, and see if they sound identical. The empty side may sound a little hollow while the full side should be a solid sound. I believe the sending unit is on the drivers side while the transfer pump is on the passenger side. That side may sound more solid.
2) also at the point you know it’s low, can you drive across an include (without danger of tipping the vehicle of course) to see if fuel will transfer to the low side. Of course you won’t get much to transfer but if you get a reading on the gauge with 2-3 gallons transferred it may also point to the transfer pump not working
I bought it as is but im pretty sure they knew about this
I thought you said it had a 3000 mile warranty. If they won't answer the phone have a lawyer contact them.
[Edit] Oh, I see that was a different purchase. Still, if you think they knew and they didn't disclose it, you could still have a lawyer call them.That always seems to get better results.
Originally Posted by streborx
Seems like typical German engineering -- why use a simple connecting tube to distribute the fuel when a failure prone pump will do the job?
A simple connecting tube won't work once the level drops to the top of the saddle.
A tube at the bottom of the two saddles would likely work.
It would work fine if there wasn't a spinning prop shaft in the way. Of course, if there wasn't a prop shaft then there would be no need for the saddle...
there is no secondary mechanical pump. They use what's called a jet pump. No moving parts.
Last edited by John CC; Jun 20, 2025 at 03:55 PM.
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