GRUSS wrote:Spoke to another tech at ford down the road who informed me that they had no in tank electric pumps.
That is correct - as they are external There's an electric 'lift pump' (low pressure) at the rear and then the injection pump (high pressure) at the front.
GRUSS wrote:My next plan was to scope the injectors but the salesman booked it into ford and i had to come away from it. This afternoon i was told that the fuel filter was replaced as it was blocked??? only time will tell if the fault is fixed and the car runs ok.
What do you think to what i've captured with the scope, am i barking up the wrong tree. It was very interesting to say the least...
A few schools of thought regards the drop - by no means the answer, nor am I saying it is this at all. (I don't have tech info on this model)
- The way you are taking feed from the sensor - the sensor may be grounded rather than powered, so when ignition is cut, there's nothing measurable on the scope. (most likely this is why you get an abrupt cut)
- The filter was restricting enough fuel to not build up the required pressure. Just enough to idle, but starve when driving.
- The sensor may be a pressure switch (unlikely) - so it switches at peak pressure only. However, you'd notice no 'variation' - just 5 or 12v when on or nothing when off. The trap would be seeing 'noise' or interference, but you'll learn to spot that by taking a reference/comparison from another 12v or 5v source and compare. [Note: I can't say anything modern uses such switch on the fuel system, but it's worth making a mental note as anything 'could' appear!]
If you find the signal cuts sharp with ignition off - and it's not because the key is turned too far,
you will need to connect your scope leads to measure between + and the sensor lead, as this will measure resistance.
As the brain is ticking...
- You could get similar issues with the car if the alternator is failing, where the voltage drops below the fuel relay threshold.