HELP -3.5 EFI starting / running problem

Ok, this is my Dad's car- and he's the real engineer not me, but I have the computer.

He is annoyed that he can't figure this out himself, but I've told him there are loads of experts and people who have had problems on here and experience from fixing them.

He has an old range rover with 3.5 V8 EFI. It has professional gas conversion.

He doesn't think this is a gas problem, but I'll let you decide.

He got shunted up rear the other day and since then has had problem, but could be coincidence.

Engine will start, EVENTUALLY. Not its usual self at all. Once started, it is rough, he can get it up to 2000RPM eventually and then it switches over to gas and runs ok.

Flick switch to go back to petrol, and it stalls. So it is not running on petrol properly at all in other words. He says you guys may say "check your injectors" - but he doesn't have the gear for that.

We were kind of hoping someone might have an idea what's going on coz he is going nuts trying to figure it out.

He has checked the 'electronics pack' under the MAF meter - taken apart and cleaned, but it has made no difference.

He has borrowed a fuel pressure gauge, but needs to make an adaptor to use it (he is on the lathe now I think).

Thanks for any answers.

Could it be fuel pump starving the engine, a bump at the rear could have damaged it, or a creased fuel line?

I'll pass that one on to him, thanks.

After a day of looking with 2 or 3 mates round (all LR nuts) he has decided to do a pin check from the back of the ECU - I just need to print off the pages from a manual for him to read off the voltages.

Hopefuly it will yield some clues - a real tricky one this.

Still no joy today.

Still trying to find the continuity test procedure page of the manual. Looks like my mate has given me the wrong manual though (on cd disc).

Everyone is scratching their heads on this one.

Pump etc is working A ok. Engine runs on gas ok so ignition system assumed ok.

Have had similar problem for some months. Runs on LPG fine but on petrol mixture is far to lean and consequenlty has no power under load.
Have changed out ecu and air flow units, checked fuel line pressures all ok. Advice from local Rangie service tech points to injector issue. Running on LPG without periodic switching to petrol may have affected spray pattern, however this is only a therory at this stage.
I am reluctant to spend dollars on removing and cleaning injectors on the basis of the current diagnosis.

Am interested in your findings on this on.

Well, he thinks it may be ok now, but still needs a few more days to be sure.

He changed ecu, MAF, all sorts apparently. Drained all fuel - did find it a stange colour (but he had used an additive recently) and he found some water in the fuel. So with all those changes who knows which one caused the problems - but fuel sounds likely.

Having said that - he says it's not running as well as it used to on gas now...