So I have this C max that stalls randomly.

Vehicle details:
Year: 2009
Engine: 1.8
Fuel: Petrol

Symptoms are as following:

1. If the car is driven a bit aggressively or a uphill for a while it will start to judder (not much but you feel it)
2. After the judder when the vehicle comes to idle (e.g junction) it will cut out
3. It will not start until the key is turned to the off position and on couple of times
4. Then it will be all normal
5. Acceleration is not regular. Sometimes it has a lot of power and sometimes it does not have the normal level of power

What is done so far:

1. Plugs are good
2. Injectors are good
3. New PCV valve and horse fitted
4. Reset the car
5. New throttle body 
6. New accelerator pedal
7. New IMRC
8. No error codes
9. No other issues to be felt

Really appreciate any advice / hint into where to look next. Thank you! 

My thoughts would be fuel starvation.

Problem with the fuel pick-up in the tank or a failing / clogged fuel tank pump.

On 7/7/2024 at 10:02 AM, unofix said:

My thoughts would be fuel starvation.

Problem with the fuel pick-up in the tank or a failing / clogged fuel tank pump.

Thank you for the reply. I’m going to do this as a last resort. Do you know if the c max has an opening from the floor or does the tank needs to be removed ?

1 minute ago, samsam2 said:

has an opening from the floor or does the tank needs to be removed ?

Sadly it is a tank out as far as I know.

On 7/9/2024 at 8:27 AM, unofix said:

Sadly it is a tank out as far as I know.

You are correct. I removed the rear seats and there is no access. Main issue is finding the correct pump. I spoke to few suppliers and they say they cannot provide the right part as for the VIN number there are few versions. And need to find the number by removing the pump.

So quick update. Managed to get the pump out and found a reasonably priced pump. Pump is on the way and hopefully I will have an update over the weekend. 

Don’t know how you’re checking the obd codes, Forscan and vlinker is the most reliable short of Ford diagnostics.

one thing I would check is the egr and swirl flaps if fitted. The vacuum control solenoids have been known to fail and are a simple fix if they do.

21 hours ago, RL123 said:

Don’t know how you’re checking the obd codes, Forscan and vlinker is the most reliable short of Ford diagnostics.

one thing I would check is the egr and swirl flaps if fitted. The vacuum control solenoids have been known to fail and are a simple fix if they do.

Thank you for the reply. Yes codes were checked and the only code found was for the accelerator pedal. That’s replaced now and fixed a bunch of issues. Vacuum control solenoids are new it seems. Guess the previous owner has changed them.

So I managed to change the fuel pump last Friday. The process was not too bad. I will put an article on how to do this one day. I have been driving the car since then and it never stalled once. I will keep testing few more days and put an update here to confirm.

However the RPM is still not stable. On cold start it starts around 1,100 (OBD reader values) and then slowly drops to about 800 - 900. This drop is not steady and minor hunting could be observed. Then once I drive it a bit it stabilizes around 700. This seems steady and no hunting is observed. The accelerator is not responsive for the 1st 1CM if pressing. If I try to press the pedal and keep the RPM at about 2000, it hunts around that value. And hard to keep at steady 2000. However, when I let it go it stabilizes at 700 and stays there happily. Last thing is that when driving if I go into costing (e,g. when closing a junction) the RPM does not come down to 700 but keeps moving between 700 and 1100 few times (fast movement) before it rests at 700. But no juddering or stalling. 

My Questions:

1. Is 700 RPM for idle normal?
2. Can the pre-used accelerator pedal I used be bad as well
3. Should I have reset the car after the pump change?
4. What else could contribute to the above symptoms?

I think we are making progress. Thank you for reading. Looking forward to your suggestions.

Hi All,

Attached is a forscan of the Accelerator sensors (App, App 1 and App2). As you can see APP1 moves when the pedal is pressed but APP 2 does nothing. Sometimes APP2 spikes down to -12 value.

Can this be an issue with the accelerator. Also none of these lines are pretty straight forward when idle. They move ever so slightly. Wonder if it's just how it is.

Appreciate any feedback / advice. Thank you!

On 7/14/2024 at 5:04 AM, samsam2 said:

So I managed to change the fuel pump last Friday. The process was not too bad. I will put an article on how to do this one day.

My C-Max (TD 1.7, 2010) has had its low pressure fuel pump completely die. Confirmed by unplugging the fuel pipe in engine bay and nothing observed flowing when key turned to "on" or cranking. It was intermittently dying for a few weeks before it completely quit on me last week. Neighbour who's a hobbyist mechanic tried getting at the pump but said best way would be to cut a hole in the floor under the rear seat. It sounds like that's not what you did. I really need the article on how to replace the fuel pump, if you don't mind! Don't want another hole in the car if it can be helped. TIA!