Depends on what the inside of the tanks like, water in it, gunk, rust. Ect.
Don't clean you're injectors with carby cleaner from a pressure pack, will wreck the seals.
Just makesure you have all the injectors in there house correctly cliped in and plugged in propperly.
You could swap two injectors( the faulty looking one and a good one) and see if it starts to miss on another cylinder or if it's the same and then spark or compression related.

One more thing, ages ago when I first got my eb I did plugs and I didn't do em up tight enough and it was loosing a heap of compression through the thread.
They dont have to be hella tight but you do wanna crush the crush washer on the plug.

injectors can glaze and block up if you run on lpg most of the time,get them ultra sonic cleaned,they will check spray pattern and volume,and match them.then change the fuel filter again,all the stale fuel and junk in the tank.then go for a run.

actually what about a dead map sensor ?

or ISC ,

i hate gas vehicles im hopeless at them but there good when they run fine the cost savings are awesome

have you tried to reset the ECU by take the battery leads of over night

Thanks for all the feedback guys
So I'll probably start ruling out the simple fixes: ecu reset, check plugs, swap injectors

As for map sensor etc I'm not sure whether these affect petrol or both LPG. Cos lpg runs perfectly so hopefully that can aid in the diagnosis.
Absolutely fine. Starts with a couple cranks, good idle, good power. Everything.

you have done the first thing, (change filter).
here is something to try, remove the fuel rail from the manifold leaving the fuel lines connected and injectors clipped in the rail, you might want to wear eye protection, get someone to crank the engine (on petrol only). this will show you if the injectors are letting petrol through..

if there is no fuel or very poor spray from the injectors remove the injectors and get them cleaned properly..

if it runs fine on gas your plugs are fine,

Hi there. I have this exact same problem happening with my AU Marlin ute. Did you get a diagnosis on the problem, and if so, can you let me know what the problem was and how you fixed it? Cheers in advance. Mick.

Hi mate,
I have unfortunately not successfully diagnosed the problem

I have not done the fuel spray check as troyman suggested yet

I got too busy in the last months and this project slipped by the wayside.. at the moment the Falcon runs just fine on LPG and I've been content to let it go for a bit
The flaky thing being the fuel gauge doesn't display the pressure properly (almost always at zero), and I have no backup petrol!

Planning to take it in for an electrical diagnosis next.
Will report any findings here

Thanks heaps for the reply. I will watch the forum for any updates on your problem. I was told by my cousin (mechanic for 25years), that it would most likely be my injectors that are gummed up with crap. If that wasn't it, he told me to look at the internal fuel pump as the sock would be probably filled with crap hence restricting the fuel flow. At the moment I have resorted to driving the ute on gas like you are doing. Also, can anyone tell me if I still have to drop the tail shaft and diff when changing the fuel pump on a dual fuel ute? I stuck my head under the ute and after close examination it looks as though the fuel tank would be fairly accessible to remove without too much other tinkering with tail shafts etc... Can someone fill me in on fuel pump removal for a AU Marlin dual fuel ute, as I can't seem to find anything on google or Fordmods regarding this work??? Cheers. Mick.

There might be some gunk/varnish type stuff/water/other crap in the tank, clean it out.

Gab

Cheers for the advice Gab, appreciate it heaps!