MK4 1.25 Power drop/running issue

[james132]

Hi all,

A few weeks ago I picked up a tidy little 2000 reg 1.25 zetec fiesta.

Id noticed a few little strange things shortly after while driving. One being when turning left at some speed (coming off a roundabout onto a slip road) accelerating it would slow down as if you'd applied some brake, revs dropping with speed. Checked over brakes etc thinking there may be something seizing up or a hose getting nipped but all is fine.
Then today when driving home from work it seems to have developed a power/surging issue between 50 and 60mph. Power drops off and hits a flat spot, and seems to surge a little too. This is mainly happening in 5th, but occasionally happens when going through the gears at slower speeds but not as noticeable. But it seems to hit 60 and its like you just hit a wall, and starts to slow dropping to 50 or lower. 

I'm stumped as to what it could be, I've sprayed brake cleaner around the intake manifold, hoses etc whilst its running to try and see if there is an air leak or something like that going on and had a good look around and seems to all look ok. I've just checked the plugs and they look fine. Air filter is clean. It was serviced approx 1500 miles ago and has only done just over 35k.

The only other thing that could possibly be related is that it struggles to start sometimes on first turn of the key, it will idle a bit lumpy. Turning it off and back on seems to sort that every time.

Any advice would be much appreciated.

Thanks.

[Kevin#95]

Try cleaning the connector that plugs into the throttle position sensor. Unplug it and spray wd40 onto the pins, spray both parts of the connector. Intermittent electrical connections on the tps could cause these problems.

[james132]

Thanks for the reply Kevin, I will have a look later today. 

[IHateTheMK7.5Fiesta]

could maybe need a service or the core plugs in the head are leaking causing the spark plugs to play up.

[james132]

Update - Sorted

Decided to have a look at the fuel pump, removed it from the tank to find a split in the hose between the pump and the outlet pipe (inside tank). Someone had been in there before and replaced one of the pipe clamps and done it up to tight causing the pipe to split. £4 later and its sorted.