Starved or out of fuel?

[Mysticality]

I started my RS one morning and backed out of the garage - the engine slowly lost revs and puttered out... No CELs, no nothing. Started it back up and it was fine again.
Maybe they all do it once.

[Hillbilly]

Vacuum lock in the tank Maybe I really dont know but have heard of some cars getting that.

[bobski]

Vacuum lock in the tank

I've had vapour lock before and it recovered (different vehicle).

It still has 10 litres of fuel, which is quite a bit. I'm leaning towards a fuel pump issue inside the tank. The interesting thing I noticed after rewatching the before/after video was that the fuel gauge didn't move when I put 5 litres from a petrol can in (it was sat on about 1/8 of a tank before and after). Maybe its a simple setup issue? Car settings set for 50 litre tank... I assume thats electronic even though the float is mechanical?

This guy gives a pretty good run down on the in tank fuel pump.
https://www.youtube.com/watch?v=5hTNWo3E4nE

[bobski]

Scarily, this has happened again while my wife was sitting on 100km/h on a highway (with over a quarter of a tank). Which is just what we've been worried about. :/ Thankfully she was able to stop safely and the car restarted immediately. I'm not particularly happy, its getting dangerous, but hopefully Skoda can sort it for good.

Skoda have looked at my Superb and believe its the fuel tank level sensor and are getting a replacement. This somewhat gels with the fuel gauge not moving when I put fuel in after the last breakdown. However, it doesn't gel with if it thinks it had an 1/8th of a tank, definitely has 10 litres, but wouldn't start?

Question for the brains trust.
I'm no mechanic, so possible dumb questions - but surely this sensor isn't responsible for allowing fuel though??? Wouldn't that cause many faults like this one? Shouldn't it pump fuel if it has it (possibly engine protection?)? I know VW went through that whole "sudden deceleration thing" before and I haven't followed what happened after that hit the headlines, but now I'm in that situation I'm wondering if we are seeing it?

[woofy]

I had a fuel sensor play up for 12mths and it turned out the apprentice hadn't plugged it back in its socket in a Mazda 323 we had when they changed the fuel filter which was under the rear seat. They literally smacked the guy in the head when they found that. But in the case of that car it made no difference to running just was ****y when fuel got low in being accurate. Who knows what kind of systems these have though as they are much more complex, it might have some fail safe, you'd want the diesels to so they don't have to be primed if that run out.

[Enobar]

The trick is to give it to your mother in law with at least 300km showing to empty. That way she'll be 200km away when it stops lol.

Just kidding... some mothers in law are great. I hear.

[bobski]

Just kidding... some mothers in law are great. I hear.

Haha, she'd find her way back!

They've had the Superb for a couple of days. Don't believe its the sensor as they believed. I'm told there are two cells in the fuel tank, and they believe the pump that pushes fuel into the one it sucks from has a fault. Which would explain everything.

We've been given a brand spanking Fabia Monte Carlo to drive around in for the time being, so its not all bad!

[bobski]

Found this workshop manual that illustrates the problem. Fuel gets pumped from one chamber to the other. Ironically, it describes the exact issue. Given its in the manual, its a shame they didn't pick it up first time. However, I'm in IT, so I don't expect anyone to read documentation ha. RTFM!

Seems one of these tubes between the pumps become blocked or had an issue. You do wonder about the engineering behind this. Assuming its a packaging, weight distribution issue that leads them to require two pumps. Thems the breaks.

Skoda Workshop Manuals > Octavia Mk2 > Drive unit > 1.9/77 kW TDI PD Engine > Fuel supply, gas operation > Removing and installing parts of the fuel supply system > Removing and installing suction jet pump (Superb II, Octavia II)