Had a scare today :( (Low fuel pressure)

[rizal2510]

Not sure where to post but feels that engine category is best as it can't work wthout fuel.

Was on the way back home with wifey and son and upon reaching Glasgow, the traffic was crawling . Was about two junction away from from our exit the car suddenly stalls. Tried to start but it won't start properly, only sputters and dies. Luckily a kind recovery truck driver was a few cars behind and he stopped and pushed me towards the hard shoulder whilst everybody was driving around us.

Called up the AA and soon the bloke came, checked everything but could not find the fault. He tried to start the car but it keeps sputtering and dies.He then suggested filling up the car with fuel as he feels that it's a bit low when he thumped on the fuel tank. The thing is the fuel indicator was a bit lower than 1/4 tank and the low fuel indicator didn't light up. So off we went to the nearest petrol station and filled the car up (son thoroughly enjoyed the ride in the yellow truck whilst his dad was bracing for the worst).

It started straight away and feeling sheepish to the AA man . He told me that it could be low fuel pressure due to being stuck in the traffic and suggest that I have the fuel indicator/sender checked.

Could it be true that the car experiences low fuel pressure during crawling in traffic as was cruising at 70 mph prior to that? Or is it a sign of something worse about to come? So far I've not experience any fault with the fuel indicator. It will indicate the appropriate amount upon filling (unlike if the fuel sender is faulty) or engine shutting off due to blocked fuel filter/pump. Any ideas for me to pursue upon ?

 

[jimmy]

It sounds like you ran out of fuel, I think some MB's do suffer from faulty sender units giving a false reading. There is an electric pump that pumps the fuel from the tank to the engine, either it pumps or it doesnt, so I guess you were out of petrol.

 

[willy]

i agree with jimmy, sounds like u ran out of fuel

faulty sender units is a common fault on mercs.

same thing happened to me once, as the fuel warning light came
on and i thought i had plenty of reserve to get me to the petrol
station, but half way there my car spluttered and died.

 

[sym]

My fuel gauge is generally fine - apart from once when it behaved strangely after brimming the tank ..... but being aware of the problems documented here and elsewhere, I don't trust it an inch, and always base my fill-ups on mileage covered, rather than what the needle shows !

S.

 

[rizal2510]

i agree with jimmy, sounds like u ran out of fuel

faulty sender units is a common fault on mercs.

same thing happened to me once, as the fuel warning light came
on and i thought i had plenty of reserve to get me to the petrol
station, but half way there my car spluttered and died.

That's the thing...the needle was just below 1/4 and the fuel warning light didn't light up, so I was thinking I should be on safe territorry. Normally it would light up at the slightest dip below 1/4 tank but sadly not today...

My fuel gauge is generally fine - apart from once when it behaved strangely after brimming the tank ..... but being aware of the problems documented here and elsewhere, I don't trust it an inch, and always base my fill-ups on mileage covered, rather than what the needle shows !

Having experienced it, I would do the same. Not going to trust the thing one bit ..better safe than calling up the AA man saying I might have ran out of fuel again..

The fuel sender check would go into the list of things to check at the next service interval...(the list keeps growing)

Thanks guys..have a banana :bannana:

 

[DITTRICH]

...and a few spare litres in a metal cannister in the boot wouldn't be amiss? Frankly, MB fuel gauges can be very creative with their readings. My 1999 W202 C230Ks gauge has played up twice and later mysteriously corrected itself both times. I won't bore you with the details, but instead suggest as above.
Regards
Les

 

[BenCF]

From a technical point of view - the modern fuel gauge system is not just a hot-wire needle display connected to a big rheostat in the tank.

The fuel 'sender' will probably talk to the ECU directly or via CAN bus (on later models), then this 'data' will be sent up to the dashboard controller where it is then converted into needle drive.

So whilst the sender could be faulty it could also have been a software bug or error in one of a couple of processors en-route.... Car software is NOT as well written as you think and the fuel gauge system is unlikely to have anything like the money/time devoted to it's development and testing as another system (e.g. ABS).

It could have been just 'one of those things'.....

 

[Ted]

You could check that the fuel tank is venting properly.
I have seen a tank start to collapse from the bottom, pushing the float of the sender unit upwards, giving exactly the symptoms you describe.

just a thought.....

 

[johnnyboy]

same problem with my CLK 320. Ran out when the warning light had just come on. has become very unstable since. At the moment it is reading empty. But in the morning give a proper reading. one for the techs I think!!!

 

[Stratman]

Ted wrote:

You could check that the fuel tank is venting properly.

That very thing happened to me years ago.

I had a Daimler V8 (like a Mk2 Jag) which used to misfire when pressing on above about 60 or 70. I renewed the sparky bits, but it made no difference. Things got really bad one day, so I pulled into a garage for a firkle under the bonnet, but went to put some petrol in it first. As I undid the filler cap, I could hear the tank unbuckle itself. The vent tube, which also doubled as an overflow tube, had become blocked with mud. A bit of poking with a thin-bladed screwdriver and I was on my way.

The downside was that it now accelerated nicely, but I could almost hear the vent whistle every time I floored it!