The V8 Owners Forum -

my vdp efi v8 suffers from bad starting when hot.cold great .hot starts but has to be left to idle or wont run smoothly.as though missing then suddenly bursts into life.any ideas?had fuel vapourising suggested and to fit a relay to allow pump to run for about 30 seconds before fire up.any one else had or having this problem? thanks dave

Hello Dave. Rover said:

Problem: Fuel vaporization can occur at the injectors when a vehicle with the engine at warm to hot operating temperature is parked in the sun for a short period and then restarted. Should a customer complaint of this nature be experienced, the following action should be taken.

Solution: Provision has been made for the fuel pressure to be increased temporarily during engine starting and for a short period of operation after engine start-up. As this effect would be undesirable if it occurred at every engine starting cycle, provision has also been made for it to only apply when the engine is at a high operating temperature.

Interested? Get the story how to do that here. Contains "point to point" wiring instructions, but only an un-verified circuit diagram. Keep in mind Rover designed this solution to overcome age-related deterioration with the Efi system and there is a potential alternative route. Return the Efi System to "as new" condition, taking into account the different fuels currently available (low RON, unleaded), therefor looking closely at ignition timing as well as the Efi set-up.

A good place to start, the 15 point Efi Health Check specified here: All the Efi components referenced in the Health Check program are described in this archive., plus, a copy of the Efi Ops Manual would also help!

There are some work-arounds.

# Auto car solution, Car in gear, turn the ignition to crank, car wont start but fuel pump runs to purge the vaporised fuel from the fuel rail.
# On a Manual car, disconnect the White engine harness multiplug below the coolant expansion tank, crank, engine will not start but the pump runs as described above. Reconnect multiplug and crank.
# Fit a fuel pump "run switch" to do the same, before cranking.
# If not inconvenient, raise the bonnet and wait for the engine to cool.

dave fordham wrote:my vdp efi v8 suffers from bad starting when hot.cold great .hot starts but has to be left to idle or wont run smoothly.as though missing then suddenly bursts into life.any ideas?had fuel vapourising suggested and to fit a relay to allow pump to run for about 30 seconds before fire up.any one else had or having this problem? thanks dave

The pump already has a relay.

As it's a VDP EFI it is an auto? If so, turn the key to the start position with the car in drive for about 30 seconds. This will run the pump - but not obviously the starter. If this sorts things it is likely vapour lock.

Try this first and report back if it works.

thanks dave.this car is a manual.the suggestion about putting a relay in was to allow the pump to run but not crank the engine over.leaving original relay in .they said to connect through another switch,bit worried to do this incase any back feeding through system

dave fordham wrote:thanks dave.this car is a manual.the suggestion about putting a relay in was to allow the pump to run but not crank the engine over.leaving original relay in .they said to connect through another switch,bit worried to do this incase any back feeding through system

You could, of course, use some for of timer - but a simple push button switch would be easier.

+12 volts feeding the push switch (from say the W pump feed wire from the ignition switch) then to the WG wire to the pump relay coil. This WG wire comes via the steering module which incorporates diodes, so there's no danger of 'your' volts going where they shouldn't.