For starters -- Ranger '04, horrible cold start, which involves stuttering, detonation-like running and finally engine stalling. Fuel filter changed, no air in the system, essentially all possible steps taken, parts checked, but the problem persists.

Now, to the topic title. I found out that when I depress the clutch pedal an inch or so that the sensor switch triggers but not the clutch itself, the engine starts running fine! It doesn't sound like it's going to blow and then stall. After thorough warm-up the engine starts running so that I can drive the car, only slightly hesitant and occasional jittering (barely felt).

So, I'm asking what is the function of the clutch sensor switch for this particular model.

Dealership is clueless, too old car for them they say. Professional workshops are willing to change the defective part or parts but don't even touch the car to diagnose the problem. They assume the fuel pump is faulty.

My visit to one independent mechanic ended with a diagnose of worn out pump and a mess-up of idle revs. But there are no starting issues, if the pump is worn, then it wouldn't start when the engine is warm, would it? The mileage is rather low as well. And after my last findings it is clutch switch dependant.

Well, on the mk3 Mondeo, the clutch sensor switch tells the ecu that the clutch is engaged so if on cruise control, will cancel it. Also, it tells the ecu that if engine idling (700rpm)to increase the revs to 1krpm to avoid stalling. 

I had a non-working Clutch sensor switch on my MK2.5 Focus Diesel for a long time and it did not affect my engine at all. My engine ran exactly the same before and after I changed it. 

15 hours ago, Tizer said:

I had a non-working Clutch sensor switch on my MK2.5 Focus Diesel for a long time and it did not affect my engine at all. My engine ran exactly the same before and after I changed it. 

Really? Well this guy's problems were solved when he finally replaced it. (read on..)