Hi,

I've had my old focus 1.8 petrol for about 5 months now and whenever It goes lower than quarter of a tank it cuts out and has a total power loss at high revs and I have to stumble home.

Any ideas what could be causing it ?

Thanks.

May not the same problem - but I owned an Alfa Romeo that build up a so strong vacuum in the fuel tank that it caused the same problems you have. The solution was to drill a tiny hole in the fuel cap. Anyway - you can try this by just remove the fuel cap when you have this problem, releasing the vacuum - and check if the engine runs ok.

I would say that your probably looking at a clogged fuel filter. I wonder if the tank gets low and takes deposits into the filter, this combined with a lower pressure is my thought. get the car a good service, have the filter changed, and if you can clear the tank out that would be the best answer...

were assuming the fuel sensor is giving the right info and a quarter of a tank isnt actually on empty

That is also true, the best answer at this point is to top the car up to full and drive your car on a bumpy road (old cobbles are best) this would ensure that if it is stuck then it is gently shook loose!

Thanks for the replies, Ive just found out it still does it when I have over half a tank of petrol. Ive had this problem on and off ever since I bought the car 6 months ago. I replaced the fuel filter, TPS and battery and it has been running fine for the last month but now its started doing it again. I just went to the petrol station which is only 2 miles away and it started doing it on the way there and on the way back ( after the petrol cap had been opened ) it seems to do it worse when I put the car under load at high revs. Any ideas ?

sounds like a fuel pump issue, not enough pressure to get the fuel how it needs to be...

Thanks yes I think I might invest in a fuel pressure guage to check it. Problem now is finding one with a long enough hose so I can test it while driving. Any recommendations ?

Ok ive bought a fuel pressure gauge and its reading 40ish psi on idle and 50psi on throttle which I guess is normal. I've taped the guage to the windscreen so I can test it while driving and see what happens to the fuel pressure when the fault happens but sods law I cant get the fault to happen so il have to leave it stuck to the windscreen until it happens again.

Is there any problem with leaving the gauge plugged into the Schrader valve for long periods ?

Also I tried to test the fuel volume but when im holding the button on the gauge the car cuts out, any ideas ?

Thanks.

Ive been driving around for a couple of days with the guage attached and it seems to read around 50psi most of the time.

The fault just happened and the guage still read 50 psi. Does this mean theres no problem with the fuel system ?

Thanks.

Well you need three things for combustion, fuel, air and spark.

If you're quite happy the fuel is there at pressure (leaving only the injectors unchecked) then now would be time to double check things like air filter, HT leads, plugs and coils.

I have already replaced the air filter, plugs, leads, battery and coil pack. Don't know what else to do now :(

No offence but why not have a desler look at it youde have saved money on leads coil packs air filter etc they can use the live data theres so many sensors etc tgat you cant check without reading the live data theres a vacume hose connected to the throttle body that collapses when revving the engine the pcv valve can jam increasing crankcase pressure theres 02 sensors that could be faulty temp sensors etc in these cases the dealers the cheaper option

I did but they couldn't find anything wrong with it. 95% of the time its fine.