Petemcman

Hi Everyone, I Put £50.00 worth of unleaded in my car on the 12.01.17 and the car broke down immediately on the forecourt.

I had it towed to the garage where they changed the MAF filter throttle body and the car still wouldn't start, I insisted that that it is something to do with the fuel, so they drained all the fuel out and ran the car from a separate container and the car fired up straight away but was still spluttering alot.

They then changed the fuel filter which slightly improved it but still wasn't right, they then added some fuel additive to try and flush the system through and this made things worse.

The mechanic then removed the fuel pump relay and said the car wouldn't start so he suspects that it is the fuel pump but doesnt want to do this as he isn't 100% sure so he has recommended i take it to the dealer to get some proper diagnostics on it.

The Porsche Dealer confirmed that was indeed the fuel pump and have fitted a new one at a cost of £630 inc vat. the car was road tested and ran for 45mins in the workshop with no further issues.

So I went today to pick up the car today drove it to the nearest garage which was less than half a mile away car drove perfectly. So i put £30 of premium unleaded in and immediately the car breaks down again, with exact same issues.

Has anybody any ideas what is going on, there are no codes showing, the just idles and then tries to die and will pick up to normal revs at the last minute but if you try and drive it it just cuts out.

My Car is a 2004 V6 3.2 cayenne s

Can Anyone please help: And has anyone had a similar experience, Thanks in Advance.

RickGrimes

Just a wild guess but maybe the coils?????

Rod Croskery

If it were an outboard motor on a boat I would loosen the gas cap.

Could the breakdowns with your 04 Cayenne be the result of a growing vacuum in the tank as fuel is consumed?

My '02 Tacoma is hard to start after a fill-up. I have learned to give it half-throttle until it's running. At all other times it starts and runs perfectly, and has done so for the 9 years I've owned it.

Petza914

I agree with Rod. Since it only happens then you fill up, sounds like it could be a faulty gas cap. The other thing you might try is cycling the key twice before engaging the starter this will prime the fuel pump and build more pressure in the system initially. Maybe once you get it running on the restart, it will stay running, but there's obviously something wrong somewhere.

Edward 96 Viper GTS

how low was the fuel level before you refueled. if you run it too low, the pump doesnt have a lot of pressure. it will take several cranks and aprox 10 min, then it will fire up and run fine. has happened to me 3 times. dealers says dont run it too low before refueling.

skiahh

Not sure it can happen in these cars, but it sounds like vapor lock.

Does the car ever have issues firing back up if you run it for a while (get the engine up to temp) and then shut it down for a short while before starting again? By short, I mean about the same amount of time it's off during refueling, vs running into the store for a while.

Andy E.

A previous poster had this exact same problem and it ended up being a defective tank vent check valve or vapor cannister purge valve:
https://rennlist.com/forums/porsche-...r-fuel-up.html
https://www.ecstuning.com/b-genuine-...e/95560524100/

TomF

This ^

Cheers,
TomF