I have recently purchased an EF Fairmont which has an IMPCO LPG setup.

Never used/had any IMPCO gas setup in my life so this is the first.

Anyhow to the problem, every 1min & 20sec or so the LPG cuts out & then kicks back in.

It won't do this when the car is cold, so when i first start her up for the day it won't do it until the car has reached its normal operating temp & then it will happily do its little quirk every 1min & 20sec.

Now driving on a very long trip yesterday the car did this for most of the trip however there was a stretch of about 1 hours driving that it stopped doing it & worked perfectly fine.

Anyhow now to detail the issue as best i can

1. The LPG fuel gauge (located with the LPG/Petrol Switch) will blank out (meaning no lights are on)
2. The car will run fine for around 20 - 30 seconds after the above has happened.
3. Then the LPG fuel gauge will turn back on.
4. At this point the car will be without no LPG fuel (For around 1 - 2 seconds) & will then work normally again for another 1min 20sec or so.
5. The above steps are repeated over & over again.

This problem doesn't occur when i am using Petrol only LPG.

Here is a link to the problem...
http://youtu.be/8uGIhwscJfA

Notice when the LPG fuel gauge turns back on - at this very point the cars engine is without any fuel & almost stalls (not on normal driving but when idling).

I have changed all the relays including the Green (Petrol) & Brown (Ignition?) factory relays under the radiator over flow header tank.

I have also changed the 4 relays (2 x Blue + 2 x Black - which should of been Grey) that control the thermo fans.