fuel/gas problem

[blue rangie]

Have a 86 classic 3.5 efi on gas . Gas system is only 6 months old ive been told that the fuel pump relay when cranking the car over is not triggering the system to work like thers no power

any help thanks steve

[langy]

I've just rewired mine, and whoever did the original job, well, was all over the place. Without pics, I can't comment on how your's is wired, but I can tell you how they wired my RR. It's a simple venturi system - no ECU.

On the fuel pump relay ( the one under the drivers seat) , they spliced a feed (fused) to the LPG switch, and then cut the coil signal feed to the EFI at the relay ( in a 4CU system - flapper - the relay under the MAF) and added a delayed cut off relay controlled by the LPG switch. ( A normally closed relay, and when you change over, the relay 'delays' for a couple of seconds before it turns the EFI off - it is wired with the solenoids) Then, all the cut off solenoids were wired together driven through the LPG switch. Then, because the wiring sometimes didn't supply sufficient power, they added a 2nd switch to boost the solenoids in case one of them stuck.

I was able to figure out the wiring colour code a little on my 'Landi' brand switch, it appears that other switches go by similar methods:

Red - power from fuse
Black - ground
Yellow- supply for a petrol cutoff solenoid ( not used by me yet )
Blue- gas supply solenoids
Brown - coil negative ( tells the switch that the engine is running)
White- Joined with green (weird??)
Green- LPG fuel gauge

This should at least point you in the right direction to diagnose what isn't working.