Hi all!

 

I bought a 1.9pd 05 Octavia in february. Not long afterwards it cut out - it was fuel starvation though tank half full. I got recovered to a local garage. It had blown a fuse - think the fuel pump one. He got it going next day just by filling the filter and jump starting. Couldn’t find a problem. I changed the filter at home.

 

Week later (maybe +100miles) same problem. Recovery guy said he would swear its the electric lift pump worn and overheating, so I got the first garage to change that for a new Bosch one.

 

Week or so later (prob +100 miles again) same problem. Recovery guy thought maybe crank sensor. I got recovered to a different garage who are normally pretty good, but they couldn't find anything. No error codes. They suggested a VW specialist. I spoke to an independent specialist in Derby, who suggested tandem pump leaking oil into the fuel (because the fuel filter was black when I changed it) but couldn’t look at the time, so I took to a Diesel injection specialist that I know and like to check that side of things. They said tandem pump wouldn’t usually cause the sudden failure, then be OK immediately after. Apparently they often leak a bit of oil into the fuel but it generally burns through OK. They looked at it and couldn’t find anything, but swapped the fuel pump relay with another (from in the car).

 

A couple of hundred miles later, same problem. I was carrying a spare battery and jump leads and immediately after the breakdown could see the fuel pump working and bleed it to the filter, but couldn’t start it until the recovery guy sprayed some easy start in the air intake. Had had an hour or so to cool down by then also.

 

So I took it to an auto electrician and got them to look - again no error codes, so they just fitted a new relay

 

This seemed to do the trick - I did over a thousand miles, then on Monday it happened again. This time I was prepared and had some easy start in the car so cracked off the screw on top of the filter - the pump was pushing fuel through there, but needed a bit of a spray in the air intake to pull the fuel through and get started. But it did start and ran fine.

 

So I'm at a complete loss! It does seem like the lift pump just fails to operate for a few seconds - then the engine is fuel starved and cuts out. I wonder if this did happen over the thousand or so miles I've just done, but because of the momentum of the car (this was mostly motorway miles) it has managed to pull fuel through once the pump starts up again (I did wonder once or twice if I felt a bit of a loss of power, but am also pretty paranoid after all this so when it didn't actually cut out I wondered if I imagined it).

 

I don't want to go to the VW/ Skoda specialist I mentioned earlier, as it sounded like they would change the tandem pump and fit a new tank, relieve me of a lot of money - and I don't think thats the problem.

I'm wondering if I should empty the tank and have a look - although if it was a blocked fuel line it seems surprising that it starts again, I guess there could be something floating around in the tank that blocks the pickup briefly then floats away?

 

Anyone got any ideas?! Any thoughts would be much appreciated - its a family car and I just can't keep driving my kids around in it if it keeps cutting out.

Thanks

 

Mike

 

 

 

 

 

 

I had all sorts of similar problems on my MK1 with air being drawn into the system from around the O rings of the white plastic valve (non return IIRC) that fitted into the top of the fuel filter, it would seal on my old 200K plus mile filter but suck in air intermittently on any new one.

 

Eventually I found that I had reversed the feed and return pipes to the fuel sender unit and the fuel pump was sucking like mad to eventually overcome the non return valve in the sender which was acting as a non feed valve!

 

Its an easy mistake for anyone to make and does not manifest itself other then the tiny imperceptible power losses you report for a very long time before causing multiple breakdowns, like you I was forever having to bleed and use easy-start.

 

Maybe they have changed it on the MK2 to prevent reversal, what doesnt help is that one connector was black, the other blue and they looked identical on the B&W Haynes manual photograph.

 

Of course if I wasn't such an overconfident muppet I would have labelled them before removal.

Thanks for the reply - do you have any idea how I could check if they're the right way round without just swapping them? One is black, one is blue as you say - the bend of the pipes look right but thats not to say they wouldnt look right if I swapped them too!

Cut out again this evening, only 25 miles after last event. Does seem like it might relate to shorter journeys more, although today I was doing 70 at the time the car had done a bit of pottering around town. I'm wondering if its more likely to suck air in, or not be able to push it through on these shorter low rev journeys.

If it is on the fuel side would that explain the complete lack of error codes?

Mine looked correct when the connections were reversed, my neighbour who had better eyes than mine could just make out the difference in contrast on the Haynes manual photo.

 

You can either look at another car or find out which of the colours is the feed and which return and look carefully at the sender unit if its marked or pull it out to be sure.

 

Also look at your fuel filter in case its possible for the pipes to have been reversed there, I knew mine was OK because I had never removed them and had driven the car for 10 years without a problem before repairing the sender unit, the reversed connections did no more than create an unexplained drop in the fuel economy, it was only after I finally changed the fuel filter (ECP kept supplying the wrong ones) that all my fun and games started.

 

Your problem does sound identical.

 

I also had some similar problems at the time when i lost the fuel filler cap and used a temporary one that didnt seal, I think the tank gets slightly pressurised by the returning fuel which in my case with the reversed connections was helping the fuel pump suck against the restriction of the one way valve, might be something else to check if you have recently changed the cap.

Hi thanks for that, I rang up the diesel injection specialist who looked at the car to see if they thought this might be whats going on, or of they could say which way the pipes should be. They thought its unlikely because it doesn't look like its been tampered with, and its running really well when its running - they thought there would be a performance hit if the pipes were reversed, and you mention a drop in fuel economy - mine's still giving 60+ to the gallon on a run, even 70+ when I'm driving cautiously because I'm expecting to cut out any minute!

 

That said if anyone was able to post a (colour!) photo of the send/ return pipes at the tank end it would be nice to be sure!

 

Or any other ideas? I'm wondering about booking it into a main dealer to see if it ties in with any known issues, or if they have any more sophisticated fault code reading capabilities, but I also don't want to just give them a big wedge of money to find out nothing, or to fix something irrelevant!