Engine sputter at high revs

[Stephylococcus]

Please help - this problem has been going on for over 5 years without resolution (despite this, it continues to pass MOT) and I’m tired of being fobbed off!

Some years ago, the day after taking my 2010 Diesel Fiesta to Kwik Fit for a full service (yes, I know, rookie error - I was young and dumb) I started experiencing a problem with my Fiesta. The problem can be summarised as so:

*The engine sputters/jerks under heavy acceleration or when going uphill;

*When this happens, the engine will either lose power and only be able to be driven at very low speed or cut out entirely, the engine malfunction light (and sometimes the traction light) will come on. Turning off the ignition and restarting the car ‘fixes’ this in most cases.

*This problem occurs far more frequently when the fuel tank is low (below 1/2 full), or if it has recently been allowed to dip below 1/3 full before refilling.

I have been told by various mechanics/AA staff etc, and tried:

*To change the filters (multiple times to no effect)

*That there is air in the fuel line and to get this out (2 mechanics tried this, still have the problem)

*That a fuel injector has gone (replaced it, problem still remains)

I have been told by a car-handy friend that it sounds like the fuel pump might be going. I have told several mechanics this theory but they seem to dismiss it. I don’t know why! I am utterly convinced it is some sort of fuel delivery issue for sure as it’s the only thing that makes sense given the above points. 

Alternative theory: It might sound crazy, but at the time the problems started, I had a workplace bully/stalker and in fact, my immediate thought at the time was he might have put sugar in my tank or something like that (he had form for this - he’d mucked about with the brakes on my push bike before). Could this sort of thing explain it, and is it worth getting my fuel tank flushed if so? 

[Tizer]

It does sound like a fuel related problem, and It would be useful to know what fault codes are being thrown up when the fault occurs.

Your theory is as good as any other although I would expect it to have had a more immediate and severe effect.

Rather than guessing and throwing parts and money at the problem if were my car I would swallow my man pride and find a Diesel specialist and let them at least do some proper diagnostics. The Common Rail pumps on modern cars are driven mechanically but are very complex electronically. Depending on the make of pump, some Diesel specialists may have the equipment to drive the pump electronically to induce the fault and even if they don't, they should have much more experience and knowledge than a general mechanic.

It was not uncommon at one time for the fuel pickup in tanks to get blocked by debris, including rust and there are microbes that can grow in Diesel tanks and block pipes. I would try to make sure that you buy quality fuel from a modern outlet in case poor fuel is causing the problem in the meantime. 

[unofix]

40 minutes ago, Tizer said:

It does sound like a fuel related problem

Agreed !!

Normally I'm not one for fuel additives but I would recommend filling the tank full with Premium Diesel and putting in a good dose of Redex (follow the instructions) after having this problem for so long you might need to do it twice.