So, not the fuel pump?...

[Wildmoose]

2011 140 CR DSG 4x4...

 

Other half was driving home 4 weeks ago now, dash lights came on, car juddered, then cut out, all within a few seconds...then refused to re-start. Turned over fine, just wouldn't start. Fuel pump, right?

 

Car was recovered, RAC guy finally came out the following day. Ran the diagnostics, prodded around a bit & decided it was probably the sender pump in the tank. No sign of anything electrical, high pressure pump opened & seemed dry & he sprayed something on the injectors that was almost enough to start the engine.

 

So, recovered again to VAG specialists, but this is where it's got weird...they can't find the problem.

 

The car still won't start, but the pressure from the sender pump is fine & everything they've isolated & tested is working. Last spoke a few days ago & they were looking at the injectors again.

 

Any ideas?

[chimaera]

All relays and fuses ok? What's the fuel filter like? Is fuel getting into the engine when cranking? Timing belt ok? Cam/crankshaft position sensors ok?

[Wildmoose]

59 minutes ago, chimaera said:

All relays and fuses ok? What's the fuel filter like? Is fuel getting into the engine when cranking? Timing belt ok? Cam/crankshaft position sensors ok?

 

Thank you for the response.

 

Can't truthfully answer too many of these, but I'm guessing they would've been picked up by now?

 

The fuses / relays looked okay & VCDS etc hasn't indicated otherwise.

 

The issue seems to be between the fuel tank & the high pressure pump, but something doesn't add up.

 

Would any of those suggestions stop the car dead when it was on the move?

[chimaera]

2 hours ago, Wildmoose said:

 

Thank you for the response.

 

Can't truthfully answer too many of these, but I'm guessing they would've been picked up by now?

 

The fuses / relays looked okay & VCDS etc hasn't indicated otherwise.

 

The issue seems to be between the fuel tank & the high pressure pump, but something doesn't add up.

 

Would any of those suggestions stop the car dead when it was on the move?

Stuff that could stop the car dead would include the cam/crank sensors - it uses these to determine the position of the camshaft and crankshaft so it can time the injection pulses correctly. If it doesn't know where they are it may run badly or not at all. A timing belt that has skipped a tooth could do this too, possible without damaging the pistons/valves.

 

I doubt it's the injectors since the chances of all 4 failing simultaneously are really low. It could be the lift pump, but you say that has been checked out and is ok. I would find out if fuel is getting through the injectors and into the engine as the next step. You should smell unburned fuel in the exhaust if they are, and possibly see some white smoke. If fuel is getting in then the injection system is fine and it's probably a sensor/control issue.

 

The Skoda service manuals have a lot of detail on troubleshooting injection problems, so I'd suggest your mechanic gets a copy of this before going much further. If the problem hasn't revealed itself as something obvious then it's going to take detailed troubleshooting by someone who knows what they're doing to find it.

[SuperbTWM]

IIRC there is a third fuel pump, boosts the fuel pressure after the lift pump before the HPFP, have they checked that? Lives beside the coolant resovoir

[Nackuk]

The timing belt does not need to jump a tooth for the cam sensor to say hi im not happy, as I’ve found out and was scratching my head in confusion. If the belt was put on but far enough to the in range limit, then as the belt expands slightly with age it hits the limit for the cam sensor to say hey it’s not right.

Put a new belt on set it up right, adjust the pulley cam pulley when doing it. To be safe get a new cam sensor put in as the belt has to come off anyway to change it.

 

Mine did show in vcds cam crank sensor issue though. It allowed it to turn over but not start.

 

Although I’ve changed many cam belts, it took my two attempts at setting this one up right, even with the tools. First time it was only so very slightly out, which normally wouldn’t be an issue.

 

It got mine going again first click of the key. It’s was only minutely out by eye.

[PEETEE]

was there a follow up to this?

 

[Wildmoose]

On 24/04/2023 at 15:37, PEETEE said:

was there a follow up to this?

 

 

I thought I'd updated this thread, but apparently not!...sorry!

 

Didn't go well.

 

The garage had my car for weeks without being able to diagnose anything...VCDS couldn't find the problem & every component they isolated & tested was working.

 

Still wouldn't start though.

 

Eventually they found swarf in the high pressure pump, which had fed through to the injectors.

 

So I ended up with new pumps, injectors, filters, hoses...almost every part of the fuel system.

 

Don't have the invoice to hand, but it was well over £3k. Throw in the flywheel, EGR valve, tyres, servicing & a few other bits I've forgotten & the last year or so has cost £7k in maintenance.

 

I still love my Superb & I've stuck over 130k on it during my ownership, but I could really do with 2-3 years of trouble free motoring now.

[rbhelle]

On 31/03/2023 at 23:54, SuperbTWM said:

IIRC there is a third fuel pump, boosts the fuel pressure after the lift pump before the HPFP, have they checked that? Lives beside the coolant resovoir

Was my initila thought as well. But metal grinding particles in fuel filter and then end up in hpfp is a expensive repair....Damn his car just got expensive....