How to (LR Discovery Extra 25bhp)

Did you know that the fuel pump on the Land Rover Discovery can be adjusted to give you an extra 25 BHP? Well it can. The advantages of this will be noted by automatic owners as myself, as it can reduce the 'pull away' at junctions.

This is at your own risk! - I'd do some more research before doing anything.

So, how's it done?

1. Reduce the waste gate rod by about 6 mm to raise the turbo pressure to 16 psi. This is quite easy on the 200tdi engine (but you'll find it a bit of a pig on the 300) *Note* Try not to loose the circlip and loosen the locking nut first.


2. Make a length of 1/2 inc bar with a slot in the end to push the rod back into place (essential on a 300).


3. Use a gauge to measure the pressure by placing a 'T' piece in pipe leading to the injection pump. You will find that a fuel pressure gauge is often the cheapest to buy.


4. Remove the four screws from the power valve on top of the pump. The top of the plate will spring up, notice how far it rises on top of the spring, (say 7mm) and remove the cover.


5. You will see a black diaphragm. Mark its position relative to the casing with tipex or similar, then remove the diaphragm by lifting the edges and pulling up.


6. Remove the spring underneath. *Note* Do not move the throttle when the diaphragm is out.


7. At the bottom of the cavity you will see a toothed wheel. You need to screw this down, to reduce the lift in the top plate to about 3mm ( 7 - 4 =3 ).


8. After the above adjustment, re-fit everything to check the lift. In some cases, it may be required to remove the ali wheel and grind some off the bottom to get it to go down enough. If you examine the shaft on the diaphragm. You should see an off centre cut out, at the bottom. Re-fit the diaphragm with the deepest part of the cut out towards the rear of the vehicle. This will give you max fuel. *Note* Don't forget the spring, and to check you still have some lift in the top plate as you screw it down.

If you experience some smoke, then you have two choices. a) Increase the turbo pressure or b) Reduce the fuel a little by rotating the diaphragm either clockwise or anticlockwise respectively. No adjustment should be needed for MOT testing as C02 is relatively low to start with (assuming of course you have looked after your engine).

It is advised not to adjust the screw under the brass cap or the main fuel adjuster at the rear. This may partially increase the fuel, but is not needed here.

In summary 3 things are changed:

• Turbo Pressure;
• Diaphragm Rotation; and
• Spring Pressure.

This is not for the faint hearted though, unless you know what your doing, and your engine is in good condition, you may damage your Cylinder Head Gasket or Radiator or Header tank. Remember that Header Tanks splitting causes over heating, which in turn causes Head Gasket failure.