Ford Falcon Engine Problems

The fuel consumption is maybe a little too high, I reckon 11-12 L/  100 km would be closer to what you should get, but a lot depends on the load you carrying, the speeds you drive at, the traffic density etc, which makes it hard to be too specific. As for the engine I reckon you need to have it thoroughly checked over, it doesn't sound healthy to me.

Replacing the crank angle sensor is a good start, that's most likely the problem. The coil could also be dodgy, but I would replace the crank angle sensor first.

Rough running and backfiring are common issues with LPG cars, particularly those running the old technology as your old Falcon is running. It's usually a problem with the ignition system, such as spark plugs or spark plug leads. I would replace them.

The sort of surging you talk about suggests it isn’t getting the cold enrichment it needs to run smoothly during that first phase of driving. It’s probably that the computer is not being told by a sensor to deliver more fuel to the engine, so check the sensors on the engine, and you could check for a faulty connection in the wiring loom.

You're correct there isn't a lot of difference between the earlier series and the FG that might affect the conversion, and there are kits available for the FG. Go to one of the larger, more experienced outfits.

We consulted our LPG experts and their feeling was that it could be a spark issue. As gas takes more time to fire, it can highlight a misfire on gas and not display any issues on petrol. Testing of the coils and inspection of the spark plugs would be a good starting place assuming the basic gas system has been thoroughly checked. If it has shown this symptom since the day you had the system fitted it would be worth double checking the firing order correlation of the petrol to gas injectors, when this is incorrect it will show these symptoms. It can easily operate normally under higher loads and show these issues at light loads and idle. Air leaks a and leaking petrol injector seals can cause odd issues, although these are now normally seen on the turbo models.

The range indicated on the trip computer is calculated based on the actual fuel going through the injectors, so it’s generally quite accurate. It has nothing to do with the float in the tank, that’s connected to the fuel gauge, and isn’t necessarily very accurate.

I'm not surprised Ford fobbed you off. You asked a question they would not be prepared to answer. Power steering pump whine is quite common, as the dealer told you and you discovered for yourself by replacing the noisy pump on your BA. The only way to fix it is to replace the pump, as you did on your earlier car.

Because it's too much on either fuel the problem is not related to one fuel system or the other. I would be having the oxygen sensor checked, it's the one that determines the mixture going into the engine and it would seem the engine is running too rich.

It doesn’t sound like a problem with the gas system, sounds more like it needs a service.