Does running out of petrol damage the engine?

ramirez · 13 Sep 2006 at 09:12

Hey guys,

My fuel gauge went a bit **** up recently and I ran out of, or very close to running out of petrol

basically the engine still idled fine and would start, but would barely rev so the car didn't really move.

can this damage the engine at all?

its been running fine for about a month since this happened, but just remembered about it today.

it's a 2.5 6 cylinder twin turbo

I know on a diesel its a very bad thing to run out of fuel but wasn't sure if the same was true of a petrol.

NathanE · 13 Sep 2006 at 09:16

Generally all the crap from the bottom of the tank gets sucked into the engine. So yeah it could "damage" it I suppose but it's probably only of concern to performance cars.

merlin · 13 Sep 2006 at 09:18

NathanE said:
Generally all the crap from the bottom of the tank gets sucked into the engine.

I thought that was an old wives tale?

pinkaardvark · 13 Sep 2006 at 09:19

NathanE said:
Generally all the crap from the bottom of the tank gets sucked into the engine. So yeah it could "damage" it I suppose but it's probably only of concern to performance cars.

Hmm the fuel feed pipe on any fuel tank is at the bottom so regardless of whether tank is full or not the fuel is drawn from the bottom. There is always a metal gauze in there to prevent big chunks going through. If it was any other way then you'd run out of fuel when the tank wasn't empty. So not so sure how accurate this myth is.

pinkaardvark · 13 Sep 2006 at 09:19

merlin said:
I thought that was an old wives tale?

Firestar_3x · 13 Sep 2006 at 09:20

Worst it could do is clog up your fuel filter.

merlin · 13 Sep 2006 at 09:20

Old wives tale it is then.

Just running out of petrol isn't a problem. However, getting fuel surge high up the rev range is. That could damage the engine.

Von Luck · 13 Sep 2006 at 09:21

Dunno - I replaced the tank on my old landy and could've pebble-dashed the house with the crap I shook out of the old one (although to be fair, most of it was rust from the tank itself rather than gunk from fuel)

Doubt if running out would harm the engine much at all. Isn't it only high-pressure diesels that have problems when you run out of fuel? Think the older designs are pretty much the same as petrol engines (in terms of what effect it has).

NickXX · 13 Sep 2006 at 09:21

Yeah, surely the Fuel filter would catch all the crap?

Is it true that you can't just fill up a Diesel and drive off after you've run it dry?

ci_newman · 13 Sep 2006 at 09:25

NickXX said:
Yeah, surely the Fuel filter would catch all the crap?

Is it true that you can't just fill up a Diesel and drive off after you've run it dry?

I think it is true, yes.. The fuel pump normally needs priming when its run dry and i 'think' this can only be done manually..

Tesla · 13 Sep 2006 at 09:40

ci_newman said:
I think it is true, yes.. The fuel pump normally needs priming when its run dry and i 'think' this can only be done manually..

I think running most pumps dry will cause a degree of damage. I know my Karcher washer can get fubar'd if I were to run it dry.

Why would you want the tank to get empty anyway?

L Plate · 13 Sep 2006 at 09:48

ci_newman said:
I think it is true, yes.. The fuel pump normally needs priming when its run dry and i 'think' this can only be done manually..

most these days have the same sort of priming system as your standard fuel injected cars, but the problem is that you end up with air locks in the fuel system, it used to be a case of cracking open the primary filter or cracking the line to the lift pump to expel the air before priming manually but i dont think its the case anymore with modern diesel engines

But as far petrol engines go, modern cars have pretty good filters inside the tank as part of the pump, and then an inline filter further along the system so running dry isnt a problem, as soon as you turn the key the fuel pump normally primes and pressurises the fuel rail again

Lowe · 13 Sep 2006 at 09:58

Biggest threat is from running the pump dry as mentioned. I know with olders Renaults you only have to try it 2-3 times and it'll kill the pump. :eek:

Dtab · 13 Sep 2006 at 10:01

You cant really run them dry tho,cos if theres no fuel its not running

With diesels it will depend how empty you get them to a large extent.Stop when you get the first loss of power and you might get away with just refilling it,then again you may get unlucky and have to go the whole hog,bleeding filters,pump and injectors (in that order)

gurusan · 13 Sep 2006 at 10:02

It is possible to damage the engine by running out of gas...especially on high compression engines or turbocharged cars...they could detonate.

silversurfer · 13 Sep 2006 at 11:06

I dont know about turbos but Ive reguarly run a car on empty and beyond until it reduces the revs and finally fails even to idle and it never caused any harm.

Worst case I had was, you have to turn the engine for much longer for the fuel to be pumped all the way from the tank because all the lines are empty

Firestar_3x · 13 Sep 2006 at 11:10

gurusan said:
It is possible to damage the engine by running out of gas...especially on high compression engines or turbocharged cars...they could detonate.

That would only be for a split second, damage would be nil unless your very very unlucky, prelonged detonation is a different issue.

gurusan · 13 Sep 2006 at 11:11

Possibly...but sometimes it runs stumbling on vapors and if someone continues to press the gas all the way it can detonate very badly.

ramirez · 13 Sep 2006 at 11:21

cheers all, my fuel gauge is most bizarre - will display 20 litres one minutes then "empty" the next, then 13 litres a few mins later.

Anyone know whats likely to be causing mis reading?

Firestar_3x · 13 Sep 2006 at 11:23

Bad float gauge, change in direction / angle of the car, fuel moving around in the tank, sticking gauge, bad sender.