Not this time lol!

The recovery man was telling me about a time he had to go and recover a chap who'd filled his diesel Jag up with petrol. The chap's insurers insist that they take cars to a main dealer, so he took it to the Jag dealer. Three and a half weeks later the recovery driver found out that the Jag dealer had charged three and half GRAND to drain the tank and change the filters etc! Bad enough, eh? Well, the reason the recovery man found out about the bill was because the Jag man had only gone and done it again! This time he insisted that he wasn't taken to the main dealer, despite his insurers saying he had to be. The recovery garage drained the tank and sorted the car out for £120!

<ouch> That'll get even more expensive, then - either for him later or for whoever he manages to offload it onto...

Common rail diesels really do NOT like petrol contamination - and three and a half grand isn't expensive for the high pressure pump. Y'know how Citroen hydraulics run about 70 bar/1,000 psi? Common rail injection is up to about 25 times that... Some manufacturers apparently insist on complete replacement of the fuel system - including the tank and filler neck - if the warranty's to cover it after a misfuel.

Remind me how much your Audi PDI pump/injectors were, Simon?

I thought cleaning the carb out had cured this, as all had been well for a couple of weeks. I'd been on 20-odd mile trips in the car, on country/A roads at reasonably high speeds/much throttle with no problems whatsover. However, on going from down the M1 from Sheffield to Nottingham on Sunday it started doing the same thing as it had in the first place. Luckily we were only 3 miles from the services, so I backed off, which caused the problem to decrease, but not go away, and we carried on to the services like this at about 50 mph. We stopped for 10 minutes or so at the services and then carried on the rest of the journey with no problems (about another 8 miles on motorway and then city driving). On the way back the next day I kept it at about 2/3 throttle and had no problems.

It seems like the car runs perfectly until it's been at constant full-ish throttle for 10-15 miles or so, and then when left to sit, either ticking over or stopped altogether, it works fine again. It can also happily take a lot of full throttle use on the A and B road Derbyshire hills for many a mile with no problem.

A suggestion has been the fuel pump (it was also suggested on here). The theory being that perhaps it can't keep up with the demand for fuel on a long, fast run, but it's OK for full throttle country driving as I'm always having to slow down for corners/junctions etc. I've not tried another pump, but this one does start the car perfectly at all times, whether baking hot or having been left for a few days.

Any ideas gratefully accepted!!

Change the fuel pump..you suspect it but haven't eliminated it...?

I know I know. I'll have to get me wallet out!

Disconnect the entire fuel line at the carby and stick a 7mm bolt in the hose from the pump (to eliminate fuel coming out). Hang a solid 1 liter see through plastic container on your door mirror and fill with fuel. Bore a hole in the cap and feed a new fuel line to the carby. Go for a spind to see if your problem is gone.

Could just swap 'em over between two of the fleet, and see whether the symptom moves...?

Did you replace the pipe on top of the petrol tank when you took it out, Jono? I replaced mine last year with some of that super-duper cotton-covered pipe, and had to do it again at the weekend because it had cracked..!

Looks like most possibilities have been covered, Jono. I'd be looking at the in-line filter first (if there is one), without touching too much on the intermittent motorway thrash from Limoges to Calais one very hot summer, culminating in an embarrassing stagger onto the ferry, which only served to confirm the worst prejudices that dumb Brits have about the Deuche...

The pump can start the car perfectly, because the non-return valves are still in ggod, even though they're usually the first thing to give up the ghost. It's still possible for the pumping bist to get tired, and unable to match the load over extended full throttle driving.

Luke's hit on the rubber connection on top of the tank perishing, thus letting in air (but not letting out fuel), but the weirdest one I ever had was on our Ami8, whcih had developed a little pinhole in the metal tube of the sender unit. Took some finding... mind, it was easier on an Ami!

Plastic pipe from rear to front constricted or kinked in some way?

Running out of ideas now...

im sure youve heard this before (As i havent read every single post) but sounds like fuel to me, like its not getting enough fuel, so its not firing, (like missing a beat) so its going firing not firing firing not firing if you get me, which explains why it runs on tickover fine and with choke, because in tickover it uses minimal fuel and its obviously getting enough fuel to run,

and the reason behind it being ok on choke is because the choke varies the amount of air going into the fuel into the engine, as it has to be right, and if it isnt getting enough fuel causing the mixture to be wrong, putting the choke on would lessen the amount of air going into the carb perhaps balancing it back out,

which would explain the kangarooing

to me personnally id say fuel starvation, have you checked any fuel filters? think i saw you mention youd cleaned the carb? if so work backwards cleaning everything


sorry if ive repeated what anyone has said or youve got your problem solved but i thought id say it anyway

hope i was half useful