clutchdust
Well-Known Member
- Posts
- 1,335
- Location
- south wales
I thought I'd do this cos I'm a nice chap! There's a few threads going around on here with concerns about lack of power and/or engine light on, non start but cranks over fine, stuff like that. This thread i've started covers the most common cause. i've stuck it here in the freelander section for all to see and if the mods wanna move it to the common fault/FAQ section then they can do later.
Right then lets get started.................
First off, yes I have access to a T4 and it makes things easier but this can be diagnosed without T4 and the car that the photos below came from was correctly diagnosed by me before I even got the car into the workshop, I took the photos with my phone for warranty purposes because the printer is ****ed and I thought, while I have them on the phone, I'll share them with you lot.
The fault on the job card read....... lack of power, missfire, engine light on. or words to that effect.
First thing I did, fire it up wait a few secs for the oil to get round the engine then deck the throttle in neutral, watch the rev counter and listen. A good one will rev cleanly to 4800 RPM or there abouts, and sit there, on the limiter with no hesitation, missfiring etc.
This one revved to 4000 RPM missing and smoking, under load it wouldn't make 3000, some won't rev past 3000 in neutral and the engine light always comes on. First thing I thought, "low pressure pump is ****ed", seen it enough times!
That is how I diagnose a low pressure pump failure without T4, so far, touch wood, I haven't been wrong.
To confirm this, I put T4 on it and had to for warrany purposes as LR wanna see whats going on.
Stored fault code
Select "real time display" and watch, in real time, whats going on........
Idle........
I've circled the low side fuel pressure and the engine speed to make things clearer
At idle, the low side pressure should be about 350kpa, this one's 284 so it's low but not low enough to cause starting or idling problems, this will come later if the fault was left uncured.
With the throttle planted to the floor, it made 209, so the pressure really drops off as engine speed increases and if under load, it'll drop off even more as fuel demand increases, it should stay over 300kpa
With a new low pressure pump fitted, you can see the immediate effect on low side fuel pressure, also note that the high side has increased by 1000kpa too (circled).
And at full throttle, engine now hits maximum speed with no hesitation or missfiring and the fuel pressure stays above 300kpa
Right then lets get started.................
First off, yes I have access to a T4 and it makes things easier but this can be diagnosed without T4 and the car that the photos below came from was correctly diagnosed by me before I even got the car into the workshop, I took the photos with my phone for warranty purposes because the printer is ****ed and I thought, while I have them on the phone, I'll share them with you lot.
The fault on the job card read....... lack of power, missfire, engine light on. or words to that effect.
First thing I did, fire it up wait a few secs for the oil to get round the engine then deck the throttle in neutral, watch the rev counter and listen. A good one will rev cleanly to 4800 RPM or there abouts, and sit there, on the limiter with no hesitation, missfiring etc.
This one revved to 4000 RPM missing and smoking, under load it wouldn't make 3000, some won't rev past 3000 in neutral and the engine light always comes on. First thing I thought, "low pressure pump is ****ed", seen it enough times!
That is how I diagnose a low pressure pump failure without T4, so far, touch wood, I haven't been wrong.
To confirm this, I put T4 on it and had to for warrany purposes as LR wanna see whats going on.
Stored fault code
Select "real time display" and watch, in real time, whats going on........
Idle........
I've circled the low side fuel pressure and the engine speed to make things clearer
At idle, the low side pressure should be about 350kpa, this one's 284 so it's low but not low enough to cause starting or idling problems, this will come later if the fault was left uncured.
With the throttle planted to the floor, it made 209, so the pressure really drops off as engine speed increases and if under load, it'll drop off even more as fuel demand increases, it should stay over 300kpa
With a new low pressure pump fitted, you can see the immediate effect on low side fuel pressure, also note that the high side has increased by 1000kpa too (circled).
And at full throttle, engine now hits maximum speed with no hesitation or missfiring and the fuel pressure stays above 300kpa
