Running on empty - what does it really mean?

[Rawcpoppa]

The presence of unburned fuel in the exhaust system, due to intermittent or inconsistent fuel supply, may cause damage to the catalytic converter.

For direct injection engines, a lack of fuel supply may cause damage to the high pressure fuel pump, because fuel acts as a coolant and a lubricant.

Do not continually crank the engine if the vehicle is out of fuel.

I'm trying to understand why there would be fuel in the exhaust system due to intermittent or inconsistent fuel supply. If the engine is running it should burn all the fuel that enters each piston as per usual no?

[Idle]

Quick reply:- No

[Rawcpoppa]

Quick reply:- No

Looking forward to more details.

[Idle]

Slightly less quick reply:

Well, for a start, petrol engines have an optimum air to gas (evaporated petrol) ratio at which they run best and give their best power to economy performance. My aging memory suggests 14.7 to 1, but anyway it's thereabouts.

Long periods below this will result in a hotter running motor — substantially below can cause valve damage and even burn holes in pistons.

Ditto above this will result in a colder engine and unburned fuel in the exhaust system and in the oil (when you see black smoke from the exhaust, petrol or diesel, this indicates unburned fuel exhausted from the motor, and will result in poor economy.)

This has been the case for as long as there have been internal combustion engines, and never more so than today, with compression ratios of petrol motors approaching those of diesels, manufacturing tolerances very fine and materials cut to the limit (and sometimes beyond...)

A quick google will bring you more detail on the subject — probably more than you can cope with.

[Diesel_vert]

As per above, an engine needs a stable and consistent fuel supply for combustion to occur normally.

An intermittent or inconsistent fuel supply may cause the engine to misfire, a condition where fuel is burned partially or not burned properly. This allows raw fuel to pass through the engine and into the exhaust system.

As the exhaust system in a petrol engine is normally very hot, raw fuel is ignited by the heat and causes a large temperature increase. This will cause damage to the catalytic converter, as well as other components in the exhaust system.

Almost every passenger vehicle fitted with a catalytic converter will have the same warning written in the owners manual.

[gareth_oau]

[DV52]

Video

Gareth: would it be an exaggeration to call it "a timeless classic" ? Doesn't matter if it is - still an-oldie-but-a-goodie!

[gareth_oau]

there will be many here that have never heard it before.

My job as an oldie it to educate those youngsters! LOL

[Rawcpoppa]

Haven't been able to view the video yet but I have another question for you experienced guys. Running spark plugs past their due date. What are the serious issues with running plugs that are to be changed at 64,000km to say around 69,000km.

Also in my 1.4 tsi Jetta if I go full throttle in gear 3 and 4 after the engine has warmed up I feel the car misfiring then the EPC light comes on and the car disables that cylinder that was misfiring. Switch off the engine and restart and the EPC light clears and the car is back to 4 cylinders. Wasn't able to change the plugs till 69,000 so was wondering what potential damage may be done even though the car seems fine now.

[Lemonskin]

I was talking to some friends about this recently. A few told me they like to play a game to see how far they can go before running out. I was just like "why bother? just fill up when it gets low or anytime fuel is cheap". I don't get it personally. Why run the risk of getting stranded?

[Kesh]

I was talking to some friends about this recently. A few told me they like to play a game to see how far they can go before running out. I was just like "why bother? just fill up when it gets low or anytime fuel is cheap". I don't get it personally. Why run the risk of getting stranded?

Seems like a daft game to play in all honesty. Not good for the engine, and no real satisfaction in the end... at least for me. I'm blessed with a "range" guide, so I use that to determine how long I could've gone on a tank. I usually try and keep mine above half, or top up whenever the fuel cycle goes to the cheap price. Speaking of which, pumps are starting to go back up again, around the 155 mark.