fuel light bingo ends in disaster

[raharley]

So I was playing fuel light bingo and let the tank run down to pretty much empty on the 525 I've had for about 500 miles. I then put half a tank in.. 5 miles down the road (during an overtake lol), loss of power, feels like a misfire, very hesitant acceleration. I pulled over to check there was no serious problems..exhaust sounded irregular.. limped the last 10 miles home.

I thought it was weird problems only started occurring after I let the tank run down that low and then filled up... so I poured a bottle of petrol cleaner/injector cleaner stuff into the tank to try and break some of the crap down in there. After this I brimmed the tank with 60 litres.

Power is now better than before, but still very hesitant above 2500..not pulling like it should..power is uneven..not smooth..engine sounds like its working but no acceleration to match in all gears..idle is rough - computer keeps blipping it up to stop it stalling

What are the chances of bad fuel.. or lifting crap from the bottom of the tank which is now stifling fuel flow somewhere? Would a fuel filter replacement help? Anything else I could try?

Cheers guys

[phelix]

Fuel filter replacement is certainly a good start.

[bimmer_87]

Just use V power for a couple of months, it has detergents that will clean your fuel system.

[gizlaroc]

phelix said:

Fuel filter replacement is certainly a good start.

Agreed.

[VerySideways]

gizlaroc said:

phelix said:

Fuel filter replacement is certainly a good start.

Agreed.

+1

[Huff]

I hope it's just the filter, but...

If you do this a lot you can kill the fuel pump, if it's one of the type that are immersed in the tank. These are cooled by the fuel, so persistently running near empty lets them overheat.

The GM Saab 900 is a bugger for this, and the symptoms are exactly as the OP described.

[OllieWinchester]

I know its common practice, but I don't like the sound of a hot little metal fuel pump being cooled by a load of petrol swishing round it....

[MarkwG]

^^ Get your point, but the pump may not be wholly metal, anyway: for example, the tanks are often plastic, these days.

The issues around petrol explosion relate to how it behaves as a vapour - as a liquid it's quite difficult to ignite. By the time you're at vapour ignition levels, I guess the pump won't run anyway.

For the OP, I concur with the other guys - change the filter, if no better, the pumps probably stuffed. It may be the sludge knacked it before it got to the filter, anyway - I believe the filter's there to protect the injection system, rather than the pump.

[raharley]

No.. I don't do it all the time... usually fill up on a 1/4 or whatever..this time I felt lucky though

Anyway thanks for the replies - I'll look into changing the filter first.

[MarkwG]

(Been there myself - wild stab in the dark - you're male, rather than female? )

[raharley]

Haha - yes. I went past 5 stations determined to get 82.9.

[podman]

bimmer_87 said:

Just use V power for a couple of months, it has detergents that will clean your fuel system.

Flip me, you bought into the marketing hype big time didnt ya?, I dont know if you've ever looked at the head/valve area of an engine thats 3+ years old but metal scapers have a job shifting some of it.

V power for 8 weeks indeed...

[bimmer_87]

podman said:

bimmer_87 said:

Just use V power for a couple of months, it has detergents that will clean your fuel system.

Flip me, you bought into the marketing hype big time didnt ya?, I dont know if you've ever looked at the head/valve area of an engine thats 3+ years old but metal scapers have a job shifting some of it.

V power for 8 weeks indeed...

nope, but v power is revolutionary in the way it works, a clean engine will not only run better but will increase your fuel economy!

[Deva Link]

I thought these issues with low fuel and crap in the tank didn't happen these days because, unlike when cars had carbs, fuel injection systems take much more fuel than they need and then recirculate un-needed fuel back to the tank so it's constantly swirling.

Or is that not correct?

[bimmer_87]

Deva Link said:

I thought these issues with low fuel and crap in the tank didn't happen these days because, unlike when cars had carbs, fuel injection systems take much more fuel than they need and then recirculate un-needed fuel back to the tank so it's constantly swirling.

Or is that not correct?

To be honest that's the first time i've heard of that, but what i do know is running the tank empty damages your cat, anybody know how and why?

[Deva Link]

bimmer_87 said:

Deva Link said:

I thought these issues with low fuel and crap in the tank didn't happen these days because, unlike when cars had carbs, fuel injection systems take much more fuel than they need and then recirculate un-needed fuel back to the tank so it's constantly swirling.

Or is that not correct?

To be honest that's the first time i've heard of that, but what i do know is running the tank empty damages your cat, anybody know how and why?

That's because as the car is stalling as it runs out of fuel unburnt fuel is going into the hot cat.

[monthefish]

Deva Link said:

I thought these issues with low fuel and crap in the tank didn't happen these days because, unlike when cars had carbs, fuel injection systems take much more fuel than they need and then recirculate un-needed fuel back to the tank so it's constantly swirling.

Or is that not correct?

That's what everybody thinks, and is the 'accepted conventional wisdom' here on PH (I can't be bothered arguing with it anymore), but it happened to my dad (modern, fuel injected car) who now fills up when gets to 1/4.

[stevesingo]

I've always run all of my cars down to the minimum practical. Wednesday, I managed to get the 320d to show only 6 miles to empty and it took 62lt in the 63lt tank! I have run out a few times in my e30M3 SE (not a car to play bingo with!) Not one problem in 17yrs of motoring in many different cars. If a car is always run down from new then there will be no build up of crud any way, and modern fuel injected cars pump fuel through the fuel rail and at low loads only a small percentage of this is injected. So if 90% of the pumped fuel is returned to the tank 75% of the time, how many times has the last 10lt of fuel passed through the 10-15micron fuel filter? More than once I would think.

There may be other underlying issues that may crop up in doing such things. Such as a fuel pump running dry will not have any lubricant may exasperate an existing fuel pump problem.

As for fuel detergent properties, I don't know... I don't see any independent tests on detergent properties. All I know is my E30 M5 was run on Optimax/V Power for the latter 15000 miles after an engine rebuild 6000 previously.


This is one of the inlet valves, taken by endoscope...



And a piston crown...



You could still read the markings on the piston!

Clean enough for me.

Steve

[MarkwG]

I recall similar chats with my dad - I guess there are many ways of intorducing debris into the tank, some of which technology has resolved. For instance, I'm advised storing old cars with metal tanks occassionally resulted in corrosion flakes or paint getting into the system; no longer an issue with plastic tanks. The crud in petrol storage tanks - I reckon that might still be a problem?

What ever, if there's a filter there, I guess it's not purely decorative, so if it's blocked or breaking down it may give the symptoms above? In which case, changing it may help?

[Neil.D]

stevesingo said:

As for fuel detergent properties, I don't know... I don't see any independent tests on detergent properties. All I know is my E30 M5 was run on Optimax/V Power for the latter 15000 miles after an engine rebuild 6000 previously.


This is one of the inlet valves, taken by endoscope...

And a piston crown...

You could still read the markings on the piston!

Clean enough for me.

Steve

Is that an E39 M5 or E30 M3?

You couldnt ask for much cleaner than that...Perfect.