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fuel / lpg problem


siearl
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HI all can anyone help i have a 110 running a RR 3.9 V8. This is LPG converted. When i am running on LPG everything is fine but as soon as i switch over to fuel i have a massive drop in performance and the engine misfires. Have looked at the fuel line and it does not seem to be restricted or blocked. Does anyone have any ideas.

Cheers

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When I used to have an LPG 110 I recall that the distributor required quite different positions for petrol versu LPG beacuse as someone else has pointed out, LPG ignites more slowly than petrol and therefor the iginition has to be retarded sufficiently to allow for this. I found it very hard to find one setting that worked equally well for both fuels.

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to be honest i dont think it is a distrubutor problem by the way the end is running, i am more inclined to think it is a fuel starvation as the dizzy was replaced in jan and have not had any problems till yesterday

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When I used to have an LPG 110 I recall that the distributor required quite different positions for petrol versu LPG beacuse as someone else has pointed out, LPG ignites more slowly than petrol and therefor the iginition has to be retarded sufficiently to allow for this. I found it very hard to find one setting that worked equally well for both fuels.

On mine I had to advance the ignition slightly for LPG to get optimum power.

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How frequently is the car run on petrol? If never - and if the petrol has been in the vehicle for some time - then it could be the petrol has deteriorated to the point where it really isn't petrol any more. Have a look at www.go-lpg.co.uk/hints.html for other suggestions.

Or you could have a defective temp sensor & the vehicle is OVERfuelling - which can also make them run really rough.

I also think it unlikely to be a problem with the ignition side of things as you are experiencing no probs on LPG.

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It is run regualy with fuel and was filled up on Thursday.

With regards to the temp sensor how would that affect the fuel (being thick), going to start off with the small things and work from there the only other thing i can think of is if the fuel pump had gone would there still be fuel gtting to the system

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how long ago did this start happening? potentially your injectors are getting bunged up- whilst the timing could be out, it's only a few degrees to improve lpg, and really shouldn't make that much difference. however petrol injectors can get bunged up pretty quickly. Dump in a coulpe of shots of injector cleaner and some top grade fuel and see what happens.

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It has been running a bit sluggish for about 5 days, but it was only on sunday afternoon that i really lost all the power,will try some injector cleaner as well. Is there any way to egt the injectors out to see if they are blocked.

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injectors can be tested and ultrasoniclly cleaned to remove deposits- much cheaper than new injectors (whifch are £££ iirc). remve injectors isn't technically dificult but it is quite time consuming (although most things i do seem to be time consuming :D) remove most of the gubbins from above the plenum to give you acces to the fuel rails- unscrew the fuel rails, unclip each injector from the fuel rail (easy to do) and then the injectors can come straight out- they aren't easy to get out though!

Wonder if you're ful pump is on the way out? easy way to check this is to unscrew the return fuel line to tank, if at idle there isn't a very good flow of fuel returning to tank (on theg rounds that fuel pumps send the same amount of flow which is regulated for pressure not to flow rate) then you have a fuel supply problem- checking this first is going to be a lot easier than messing around with injectors.

To be honest i never got my lpg running as well as i might have wanted (although maybe if i had gone for injection this not have been the case). Either petrol worked fine and lpg backfired, or lpg worked fine and something went wrong with the petrol. On on particualarily memorable day i couldn't get the car started on petrol so spent the whole day removing fuel pumps (by goign through the boot floor), fuel injectors, petrol lines etc etc before realising i had blown a fuse- DOH.

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With regards to the temp sensor how would that affect the fuel.

The coolant temp sensor can effect the fueling on EFi engines as it tell the ECU the coolant temperature and the ECU then decides how much fuel is required, ie if the engine is cold more fuel is required. What often happens is that the sender fails and the ECU thinks the engine is cold and sticks a load of extra fuel in which leads to a misfire/poor running and even worse fuel consumption.

HTH

Pete.

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not having excessive fuel consumption, when you start the engine you can hear the fuel pump kick in but while it is running if you feel the hose between the pump and the filter it seems to be spurting it is that normal

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no

flow should be steady and high pressure, you shouldn't be able to feel pulses- even non pressured efi pumps don't "pulse". the pressure from an efi pump should mean that the flexi fuel hoses feel rock solid (at least i've never been able to squeeze mine!) How noisy is the pump? it should be no more than a background whine, and not particularily audible over the rest of the noise and LR makes.

Not being silly but you definately have a good amount of fuel in it don't you? ignor the gauage of course which could be faulty.

I don't know about defender fuel systems- does it have an intank pump and does that pump have a filter on it? is the pump readily accesible by any chance?

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The engine is in a Defender, the fuel tank at the rear does have a sender in it yes, as regards whether it has a filter or not i am not sure. It is definatly pulsing between the engine fuel pump and filter. With regards to amount of fuel has over half a tank, was filled to top on thurs at local tesco's

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FIXED - Having checked all the pipes between engine and tank and back again, had the pipe off the pump and going in to milk carton to prove working, replaced the fuel filter and still no joy, even checked the air filter. as i was bout to throw a hammer at it i spotted a tear in the pipework between the air flow meter and the engine bit of sticky tape over the hole (temp repair), started it up and ran like a dream. always the smallest things

THANKS EVERYONE FOR YOUR HELP AND ADVICE

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