hornet1

Hi,

type: w216 CL63 AMG

today for the first time I have used an 98% unleaded fuel instead of 95% unleaded and my car moved about 50ft before stopping suddenly. I can start the car but can't raise the RPM above 3000.

I need to drain the fuel tank what's the easiest & fastest way to do this?

appreciate it.

Ezah

I put unleaded in a diesel Merc once (first company car lol).. luckily I realised before I started the engine! I got it towed to the dealer who sorted it out for me directly as they needed to flush the tank and ensure nothing else was damaged.

Would the difference between 95 and 98 really be that great as to cause this problem?

unlucky.

hornet1

Ezah,

I was wondering the same thing what could be the problem if I used a 98% unleaded. anyway I need to flush or drain the tank.

Ezah

I know you have a 216, but the manual for the W215 states:

"Use only Premium Unleaded with minimum Octane rating of 91 (average of 96 RON and 86 MON)"

I'm no expert but I doubt putting a higher rated fuel would cause a problem. Was the tank down to the last dregs/vapour before you refilled? Could be some dirt in the bottom got sucked through or so..

Either way, best get it to the dealer. Good luck

radride

Your logic doesn't make any sense. Higher octane fuel will not cause your car to not work. Sounds like you have other issues such as a plugged fuel filter or bad fuel pump.

R.K.

alx

to the op:

huh?

are you referring to octane or percentage of lead in the fuel?

none of those will cause the drivability problem you describe though...

for octane you can run 87 and it will run like a champ, but will reduce power significantly once warmed-up and you romp on it a bit.

for lead- i dont think it matters.. actually more lead is good for valve seat lubrication... you need about 50% lead to cause cat problems... and i dont think you can buy such fuel anywhere on the gas stations anyway.

hornet1

I am aware that there isn't any logic in this but this is what happen. the tank was on 1/4 , filled it up with 98% unleaded then lost RPM and car is running on 2500 RPM before turning off.

I'll take it to the dealer and see what they say.

alx

They will say that your fuel filter is clogged because you let the tank level drop too low and the pump sucked sediments.

Or you put some really bad gas with high water content and you need to add some water removing fuel agent bought at any gas station.

Gas octane has nothing to do with your problem.

JHouse

Either you got REALLY bad gas, which isn't very likely, or this is a mere coincidence, which I suspect. Before you go to a lot of trouble I would get it on a Star Diagnostic gizmo and see what codes it throws.

Can you just siphon gas out and refill with something else? I'm sure what little is left in the tank would dilute and work just fine.

saintz

OP, I'm assuming you're in Australia or maybe the UK. The first confusion is around 95 and 98. These are octane ratings. They are not percentages. Higher is better, so that is not the problem.

Inside you fuel tank door it should say what your car takes. My guess is that either of these fuels are just fine. It probably says 91 octane or higher, so either would work.

It sounds like you have another issue. Water in the fuel could be it, but there are many other possible causes. An OBD scanner would see if you're throwing codes that might help pinpoint the problem.

hornet1

fixed it !!

removed the rear seat unplugged the fuel pump and reinstalled it again. Worked like a charm !!

do you think there was a problem with the electronics ???

another Q

what is the best OBD II diagnostic tool for benz/AMG cars ??

JHouse

What on earth made you try that? Great catch. Hope it lasts.

hornet1

JHouse ,,,,,

don't know just did it ....

saintz

That might indicate the pump is on the fritz. I would maybe buy another to keep handy, just in case. You might also consider changing the fuel filter and running a injector cleaner through there.

For OBD2 you can get the little hand held scanners for $100 range (that will read standard OBD codes, not Mercedes specific), the Carsoft scanners off eBay for about $200 (that will read more Mercedes specific stuff, like related to the ABC suspension, but can't really code anything) or the SDS/STAR system (which can do everything but is generally a lot more expensive).

hornet1

saintz ,,

do you know where can I get the SDS/STAR system and for how much ??

have 2 more benzs ML350, R350

I think this we really help me with my DIY's


Thanks