Hello All,

New member with a 2004 L322 4.4V8 with Prins LPG system (good documented service history).

This afternoon, I started the vehicle from cold and it had no power - felt like it wasn't firing on all cylinders and struggled to get over 5mph. After about 2 minutes, power returned and all seemed OK, took the car for a run and it started 'juddering' slightly when running on petrol (worse when going up a hill), but fine on LPG.

Got it home, went in for a coffee and then tried to start it again - it really struggled to keep an idle but when I switched to LPG all was was fine, switching back to petrol caused a very 'lumpy' idle. I 'phoned someone I've used before who is (I think) good with diagnostics. As a favour he came out a couple of hours ago - car started OK on petrol, but slight 'misfire' when gently revved. He ran diagnostics and zero error codes, all sensors were reporting as they should with correct values.

I drove the car for half a mile and back on petrol and all was fine! full power, no problems. Got back into the drive, switched off, tried to restart an it wouldn't hold an idle, if i quickly switched to LPG the idle picked up and held OK. More diagnostics were run with no error codes. We checked a spark plug which seemed fine.

I've just tried to start the vehicle, it (just) started but has no power running on petrol, if I switch to LPG power returns. I've also noticed that the idle speed on LPG is a couple of hundred RPM up on what it usually is and the same is true on petrol (when it will hold an idle on petrol).

So I'm clueless what the problem could be, was thinking it could be fuel pump issues but as I said, idle is now a couple of hundred RPM up on normal when switched to LPG, so all is not well on the LPG side but not nearly as bad as when trying to run on petrol.

Taking the catastrophic alternator failure I had before Christmas into account, my Wife is looking at me daggers for spending money on that "bleeping huge, bleeping money pit of a car"...

Thanks so much for any help/advice anyone can offer.

I also run a 4.4 with Prins LPG, but I've never heard of anything like that before! That is really strange....
My advice would be to take it to an LPG specialist - there is a chap in Liverpool I know who is a real whiz, unfortunately I see you're in Hampshire.... NW060

"Red Shed" - 1982 Series 3 88" County Station Wagon
"Spirit of Great Britain" - Rolls Royce Meteor V12 engine
ZG875 - Westland Sea King (cockpit section)
"Carly Rae Jeepsen" - 2006 Jeep Commander 5.7 Hemi
"Pride Of The Road" - 1/4-scale Marshall traction engine - sold
"Georgina" - 2000 Discovery 2 TD5 ES - sold
"Windsor" - 2005 Range Rover Vogue 4.4 - dead

Welcome to the forum!

As you surmise:

Fuel pump issues, or blocked fuel filter or injectors/fuel rail/fuel rail wiring

or

ECU Fuel/LPG management issues .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

Thanks for the reply - was almost convinced to problem was fuel related - failing pump or 'bad' petrol, as all seemed to be fine running on LPG. But as I said, I noticed the idle speed is a couple of hundred above normal now when switched to LPG.

So at a loss what could cause such severe issues when running on petrol, but only manifests as an idle speed increase when on LPG.

Classic fuel pump on it's way out... buy a pump for an X5 and take your one fuel pump assembly apart and just fit the X5 pump to your assembly..... much, much cheaper than a FF one...  Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

I had a classic many years ago running lPG and had no problems starting on LPG ,summer or winter.
One of the rare days my wife drove it she got low on gas so changed to petrol.
Then the problems started, The engine had no power and she could only get 15 mph the AA towed it home and the man told me he thought that the lpg had burned in the Jets out and I needed new carbs.,,,,
So I got two new (to me) carbs and the same problem, no power !!
Cutting a very long story short I found that because I had run on gas for so long that the petrol filter had dried out so much that it would not allow any petrol flow so a 99 p filter fixed the problem.

Morel of the story look at the simple things first

Graham Range Rover vogue Td6
Land Rover Defender TD5
Grand Jeep Cherokee
Discovery 300tdi
Discovery 200tdi
Series lll short wheel base
Super 7 kit car
AC Cobra (still got)

Thanks all so much for the quick replies

Good call - I'll change the fuel filter, then if that doesn't help consider the pump.

I still can't figure out why the idle is now higher on LPG? Engine at normal running temperature, so would have thought it would run on LPG only, so blocked petrol filter or failing pump shouldn't impact idle speed when on LPG?

Has it always been high on LPG? I think mine does idle slightly higher on gas than on petrol. NW060

"Red Shed" - 1982 Series 3 88" County Station Wagon
"Spirit of Great Britain" - Rolls Royce Meteor V12 engine
ZG875 - Westland Sea King (cockpit section)
"Carly Rae Jeepsen" - 2006 Jeep Commander 5.7 Hemi
"Pride Of The Road" - 1/4-scale Marshall traction engine - sold
"Georgina" - 2000 Discovery 2 TD5 ES - sold
"Windsor" - 2005 Range Rover Vogue 4.4 - dead

SWMBO's comment seems to be a common theme for many ff owners. I agree I would start with the filter as the cheapest option (and keep your fingers crossed) but keep another one handy in case there is anything in the pipes. Is it possible to get foreign object debris when filling a car nowadays? Many years ago I had a Mk1 Capri that had intermittent fuel starvation and it turned out to be small crumbs of cork in the tank. No idea how they got there, but after flushing the tank and the fuel system every thing worked perfectly. Yes I know cars didn't come with lockable fuel caps then and somebody could have put them in, but especially after the oil crisis in the early 70's they were readily available and mine had one. QUID FACIUM TIBI
ANTEQUAM ALIIS

2003 TD6 VOGUE Zambezi Silver
tows 2006 Lunar Delta 540/2

Hello Mat777 - idle at neutral on LPG and petrol has always been identical (about 650), now both are up to about 900.

Started the car a while ago, held an idle on petrol but no power at all, switched to LPG and power returned.

Only issue I've had with LPG is that when the engine is at normal running temperature and I switch the engine off, it will not re-start on LPG until after I've waited for about 10mins.

Try cleaning the MAF.

This can give lumpy running and may (not sure) affect petrol more than lpg?

I had a dirty MAF and it caused higher rpm and lumpy running.

....... Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

I know nothing about LPG and don't have it but when mine idles at 900 or higher it means the battery is low and the car enters a recharge strategy until it has charged it up enough which is normally after a good run.

As Pete said, fuel pump. I did everything else to try to avoid it (MAF, fuel filter etc) but in the end had to bite the bullet.

Thanks for the replies, very much appreciated.

I've decided to get the fuel pump changed and hope for the best

I really need to get it done by next friday, or I'll have to hire car for work. I simply don't have the time to attempt this myself, I've spoken to the mobile mechanic who came out yesterday, and he at the moment thinks he can fit the job in subject to me sourcing a pump.

I appreciate that an X5 pump can be fitted to the existing housing, but I'm really not keen to go that route partly because it's going to be more labour time.

I've spent ages looking for replacement pumps that are in stock for quick delivery, but I've only found one supplier who has 'genuine' items in stock and they are about £800, there seem to be quite a few 'OEM' options for about £400. So now I'm giving myself a migraine debating Original vs OEM... If anyone can point me in the direction of a supplier that perhaps they have used that would mean the world to me right now.