Running a car low on fuel picks up crud from the tank? Fact?
Discussion
There seems to be a generally accepted idea that running a car low on fuel will cause it to pick up crud from the bottom of the tank.
I was having a discussion about this yesterday and I think it must be an old wives tale these days, but a lot of mechanics still swear that it is the case.
Given that modern cars only have a single fuel pick up, I can't see how it makes any difference how low the fuel level is - it's still going to pick up any crud in the bottom of the tank whatever the fuel level. It made sense in the days of cars having a seperate fuel pick up for the 'reserve' tank.
Or am I missing something?
I was having a discussion about this yesterday and I think it must be an old wives tale these days, but a lot of mechanics still swear that it is the case.
Given that modern cars only have a single fuel pick up, I can't see how it makes any difference how low the fuel level is - it's still going to pick up any crud in the bottom of the tank whatever the fuel level. It made sense in the days of cars having a seperate fuel pick up for the 'reserve' tank.
Or am I missing something?
There are also several fuel filters - usually a basic filter in the lift pump and a finer one in line.. I don't see how, unless you picked up a substantial piece of crap that blocked the lift pump filter, you could ever block it.
More likely problem is never changing the fuel filter during services - I've seen Corrado ones that were probably never changed and when cut open they look like something that's just been unearthed from an archaeological dig!
More likely problem is never changing the fuel filter during services - I've seen Corrado ones that were probably never changed and when cut open they look like something that's just been unearthed from an archaeological dig!
If there was a problem at all, it would presumably be with picking up rubbish that was lighter than the fuel and hence floating on the surface.
I'm pretty sure it's a complete myth, though. The combination of the facts that the car filters the fuel and that you really should only be putting fuel into your fuel tank anyway, should protect the engine pretty well.
I'm pretty sure it's a complete myth, though. The combination of the facts that the car filters the fuel and that you really should only be putting fuel into your fuel tank anyway, should protect the engine pretty well.
ikarl said:
like one of the posts above, I opened up a tank from a mk1 mr2 (24 years old) and the inside was absolutley spotless...no dirt or crud whatsoever
Was it a plastic tank?My MGB's fuel tank had quite a lot of rust fragments in the bottom when I replaced it. Still never seemed to do the engine any harm, though.
Sounds like the consensus is that it is indeed nonsense then.
I wonder why so many mechanics seem to still think it. My girlfriend was warned not to let her fuel run low because her carb will get gummed up with the crud from the bottom of the tank.
Excellent point about filters - I hadn't even considered those.
I wonder why so many mechanics seem to still think it. My girlfriend was warned not to let her fuel run low because her carb will get gummed up with the crud from the bottom of the tank.
Excellent point about filters - I hadn't even considered those.
Dad got a brand new Massey 362 at work a few years ago, it wouldn't run for s
t. Fuel tank was full of leaves. Not bad, as it only left the factory in France 5 days before he got it. Even with a new tank and new lines it still gave bother with fuel supply for years, they ended up trading it in.
t. Fuel tank was full of leaves. Not bad, as it only left the factory in France 5 days before he got it. Even with a new tank and new lines it still gave bother with fuel supply for years, they ended up trading it in.Perhaps this theory relates more to older cars which had steel fuel tanks that would corrode.
Years ago I worked at a petrol station where they to closed off the tanks before they were completely dry due to fears about contamination, but to be honest I have never once looked inside the tanks to see what they were like, other than being big and buried below the forecourt.
Years ago I worked at a petrol station where they to closed off the tanks before they were completely dry due to fears about contamination, but to be honest I have never once looked inside the tanks to see what they were like, other than being big and buried below the forecourt.
greggy50 said:
I do know at our petrol station we have to close the pumps when the levels reach 2,500 litres or less because of the stuff at the bottom of the thank which I always found bizzare...
I will avoid filling stations where the tanker is on site because of the fear that filling the bulk tanks might stir up not years of dirt, but decades of it during the filling process. Never worry about the car tank, though, for the reasons already given.
I had this happen last week (although on a second-hand tractor) which we've just acquired. The fuel gauge doesn't read correctly (didn't know until it broke down), and it was showing just above a quarter but was nearly empty.
Both the in-line fuel filters were completely bunged up with crap - it looked like copper grease in the filter.
I think the problem comes with tanks rusting on the inside, which then sinks to the bottom and gets sucked into the filter. We have a few machines (combine harvesters, sugar beet harvesters etc.) which spend a lot of time standing still. Whe we put them away we always fill the tanks. If we ever forget, we get problems.
Both the in-line fuel filters were completely bunged up with crap - it looked like copper grease in the filter.
I think the problem comes with tanks rusting on the inside, which then sinks to the bottom and gets sucked into the filter. We have a few machines (combine harvesters, sugar beet harvesters etc.) which spend a lot of time standing still. Whe we put them away we always fill the tanks. If we ever forget, we get problems.
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