No power in petrol

I have a Range Rover p38 4.6 petrol\Lpg (2000 reg)

The car runs great in Lpg like a dream but as soon as i switch to petrol or start in petrol the car just crawls along and has no power at all (Under load). When the car is standing still under no load it revs well and seems to be no promblems.

Went to dealer and spoke to fitter and he suggested change the fuel lift pump in the fuel tank as this is a common promblem with LPG range rovers. did this and there is no change,

Now thinking could it be a blockage, fuel filter or injectors ????????

HELP PLAESE!!!!

the petrol is constantly circulating to keep the fuel pressure up at the rail. so the pump could be ferked. you would need to do a fuel pressure check. then if you de pressureize the rail and re check to see how much pressure is there again this should confirm the pump is working. a fuel filter change is also a good idea as more often than not the petrol tank is kept low on lpg's so any crap in the tank may have been dragged through

Try here

LPG Forum

MirrorSignalSwerve said:

Try here

LPG Forum

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any news on yr damaged one?

gavbriggs said:

any news on yr damaged one?

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Yeah, I'm gonna leave it. They want too much for it and are being v.difficult as its a CAT C. I think they suspect that I want to 'ring' it.

I am going to suggest that the mixture is a little out on the LPG. Your ECU has adapted for this therfore she runs well on the gas. When you start on petrol the ECU will be running on the adapted map, therfore bad running. You need to get the adaptions re-set and the the LPG set up.

I had the same problem on mine a while back. Ran fine on LPG but under load on petrol it ran like a dog and kept missing.

I replaced the MAF and it cured the problem.

dave_r said:

I had the same problem on mine a while back. Ran fine on LPG but under load on petrol it ran like a dog and kept missing.

I replaced the MAF and it cured the problem.

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I had similar, although it didnt want to even start on petrol, gas was fine, worked out after someone quoted me £200 labour to fit new injectors @ £134 each i looked into it myself and found the connections at the afm to be bad, cleaned them up and that was that, cured!!

Dam ripp off garages!!

AMF? do you mean the MAF "Mass air flow sensor"

i have bought one of ebay few months ago and when i took it for a diagnostic it came up faulty, is there a way to by pass this to see if it is the MAF?????

Also where would i get the data for my LPG set up map and how would i check this on mine?? can i buy a lead and plug it in to my laptop to update the ECU ????

Cheap MAFs from the Bay are a waste of time. They will cause you more problems then they cure, if you suspect it is dicky get it confirmed first with a specialist or get your self a Faultmate. You can see exactly what the MAF is doing with this kit. To set up the LPG you need to be able to read the O2 sensors and get live readings to see exactly what the mixture is doing. Depending on the type of sensors you have you should be getting a reading of 0 to .8v cycling every second or so(Zirconia), or 1 - 5v (Titania). You should have the 0 to .8v Zirconias on your 2000 model.

If you dont want to splash out on a diagnostics kit, a lot of the standard OBD readers offer this functionality. Or failing this you can get under the car and put extension wires onto the black wires going to the O2 sensors, lead these upto the cabin and monitor with a multimeter- a analoque one with a needle is OK. On tick over with no load you should see them cycle as mentioned. On hard acceleration they should read rich (.8v) and on the overrun 0v.

Lpg diagnostic leads are available on the bay along with the software, but at £40 + - I think they are expensive. I made my own lead (or a friend did) for a cost of £3.5 - the software was downloaded for free.

To prove its the adaptives causing the problem, find someone with a Faultmate/ Rovacom/ Autologic and get the adaptive values reset, then see how she runs on petrol.

will buy a MAF from a dealer, as i fink it is this as the one from ebay was coming up faulty,

where abouts on the the car is the fuel filter located, is there a diagram of it, as have looked in the workshop manual and just shows a pic but never says where it is or shows it????

I am assuming you have a sequential multipoint LPG system ? If so it will run bad on LPG and petrol, not just petrol. Get the MAF checked before you waste any money.

yea guys, took the hit, went to a dealer and got new MAF sens and everything works well. Just goes to show that the cheaper ones on ebay are not the same as the proper ones!!

Thanks again