I'll start by telling that I've posted this very same question on another forum and I had no luck, so I'm trying here to get as many opinions as possible. Also, the car is waiting at the mechanic's car park to be seen tomorrow (as today is a bank holiday here), but I still would like to understand the possible causes of the failure before speaking to him. So here's the problem:
I have a 2004 mk1 Ford Ka Collection, 1.3l version.
It started two days ago, I picked up the car to go to work and the engine didn't start. The starter was cranking normally and the battery was good (I had the alternator changed last week), but no response from the engine. No backfire, no stuttering, no stalling, just the starter going on. I tried cranking up until the battery died and left the car there.
I've tried again today, with jumping leads for the dead battery and the spare key because who knows, it might have been the immobilizer not recognizing the key; after some hesitations, the enginge stuttered more and more, until it fired up. I've left it running for a good 15 minutes at idle, and it was running smoothly. I've tried putting down the throttle and the engine responded as it should, nice and smoothly and went back to idle normally. I then killed the engine and tried to crank it up again, but all I had back was a terrible stuttering and a tractor-like noise from the hood. It took another good 10 minutes of trying to start the engine again and, as before, it was running normally. This happened 2 or 3 times.
Now, I've plugged in my OBD scanner and it gave me no error whatsoever, with all the sensors nominal. I can't say about the sensors values with the engine running, I'm not a big expert on those. Any idea what could be or where should I look? If it was the fuel pump or a clogged fuel filter it wouldn't have started and run normally, but that's just my opinion.
I've done the following checks:
- Ignition coil cables are ok on a visual test and have a resistance of around 2 ohms.
- Ignition coil pack seems to be ok, with the right impedance between coils 1-4 and 2-3.
- Tested with spark plug tester, and all of them lights up in sequence.
- Tested the voltage at the fuel injector cables, and it shows 11.54V between the battery negative and the positive cable. I couldn't test the injector rail itself as I couldn't find an exposed positive contact.
- Air filter seems to be brand new, it has merely some dust on it. I've also tried to fire the engine disconnecting the air hose between the air filter and the engine head (as the hose might have been dirty or clogged), but it didn't change a thing.