Petrol leak from dis-used filler pipe since LPG conversion

[PradOz Advanced Member Find all posts View Profile Close PradOz]

I have a Dec 1999 petrol/LPG Prado. After I fill up with petrol I find I end up having a small amount (cup full?) of petrol leak out of where the old main tank filler pipe was cut off. Not much you may say but enough to be a safety hazard. Dont want to go up in flames from someones smouldering cigarette butt or put up with the fumes in house from it leaking in the garage.

The main tank was removed when fitting the LPG tank. The pipe was sealed by a plastic cap and hose clamp by installer. I looked at someone elses recently and found theirs was done exactly the same and they were from interstate but they didnt have the petrol leak problem. I do know of others that had the same problem as me but not solved it. I only fill until the pump clicks off so its not an overfill issue. It happens after filling at different service stations so not linked to one servo. Didnt happen after LPG was first installed but has developed over last year to now always happen when filled or near filled. The leak is behind the left rear tyre. It doesnt happen immediately after you fill up, it happens after you drive. It makes me think fuel is going up the neck of filler pipe to my existing sub tank and then back down the old dis-used main filler pipe. If you look up under the car at this spot you can see the 2 fuel tank filler pipes and in my case where the pipe is cut off.

At Xmas I decided enough is enough when I could smell it leaking yet again. Simple enough job I thought so I bought some of the "knead it" type product for holes in petrol tanks etc and tried that. It just absorbed the fuel and allowed it to leak. I thought it was a faulty batch and removed it and bought another brand at another outlet/town. It also absorbed the petrol again allowing it to leak, and this time was leaking after driving around 150kms on petrol before I switched over to gas thinking this would stop my problem. I was wondering if there is an adhesive tape or bandage that will seal petrol if I wrap it over the plastic cap on the old filler pipe end? Or any other suggestions?

Some people have suggested that fuel automatically drains from either tank to the other as a fail safe mechanism built in by Toyota as suggested in this PP topic: viewtopic.php?f=15&t=4082

But no one has proven this to be true and even if it was wouldnt that cease after a correctly done LPG installation? See here where I have asked about this without any luck also: http://www.exploroz.com/Forum/Topic/752 ... Prado.aspx
It details that fuel does NOT purposely leak from one tank to the other.

There must be more than me on PP with this problem. I am not happy with the solution being I only part fill the sub tank as that defeats the purpose of having the full capacity. Any help or advice appreciated - cheers

[ketchup Lurker Find all posts View Profile Close ketchup]

Re: Petrol leak from dis-used filler pipe since LPG conversion

Hi ,guys im new here .
pradoz, i put mine on gas about a year ago ,ive never had any petrol leakes on it , the filler neck just has a plastic cap and hose clamp like you mentioned, but have also got a plastic bung up top blocking off that filler hole .
Problem i have is petrol fumes ,im always getting fumes through the cab ,do you know what they did to the three hoses from/to your old tank,cheers.

[PradOz Advanced Member Find all posts View Profile Close PradOz]

Re: Petrol leak from dis-used filler pipe since LPG conversion

Hi ketchup

yes mine has the plastic bung in the fuel filler neck. It isnt designed to prevent fuel running down that nozzle its to alert you so you dont fill wrong side by mistake. You will soon notice that it falls out regularly so you will need to replace it regularly too.

Check out the link i gave to exploroz and check out the replies there. You will see a reply taht netions the same problem as you with fumes in the vehicle and how he fixed it. If you dont find it let me know and i will track down what he had to say in an email to me. It basically is poor workmanship from your installer that is giving you your fume problem.

To try and see if your unused main tank filler tube will leak, can you do a test on it for me? Just remove the bung inside the filler flap and add a small amount of fuel when you fill up next time - a cup full at maximum is plenty. Do you fill your sub tank up to it clicks off? Mine never leaked for quite some time either, hope yours never does. cheers....

[PradOz Advanced Member Find all posts View Profile Close PradOz]

Re: Petrol leak from dis-used filler pipe since LPG conversion

Here is a copy of the reply i got on EO about the fumes issue Ketchup mentioned:

"when it did leak I would get fumes coming up into cabin, absolutely stunk, I pulled the inner trim off on the inside where the filler neck is, I could see the light and ground, the pipe that runs from the gas connection runs down in through the cabin and back out again, what a bodgy job, hole was twice the size then needed, and all jagged edges, no paint bare metal. Not happy jan, so I got some rust proofing paint put that on, then got some silastic and filled in the hole around the pipe, then sold the vehicle. Sorry but never again for me LPG, I wrote on here a while ago what a great job they did, as usual what you dont see you dont know about. I rang him up and told him how dissapointed I was in his workmanship, he told me to bring it back and he would fix, told him I have fixed the hole issue and would not be recomending him to anyone"

[ketchup Lurker Find all posts View Profile Close ketchup]

Re: Petrol leak from dis-used filler pipe since LPG conversion

Thanks pradoz ,im off to have a look at mine now ,to see if its sealed on the inner skin. Will let you know if any leaks next time i fill up.

[Tony&Tracey Junior Member Find all posts View Profile Close Tony&Tracey]

Re: Petrol leak from dis-used filler pipe since LPG conversion

Hi Prad Oz,

i have a 2000 GXL that i converted to LPG within a month of buying it 18 months ago. i understand what you mean by the small amount of overflow. but it has only happened to me once or twice. i use petrol generally only to start the vehicle and then it automatically switches over like most units today. the only exception is when the wife is too lazy to fill the LPG and the button to petrol is easier to push !! when i fill up, i usually stop at the first clip as well. however if we are on a trip, and i fill the sub as a precaution, when we stop for a break, we can have a slight witness mark on the ground. i understand that petrol expands and contracts a fair degree with temperature, therefore i assumed that it expanded whilst driving and this was just a release.

on another note, i had my mechanic do this conversion and instead of the standard Prado tank @ 60 litres or so, he installed a (dare i say but....) a Nissan Patrol tank @ 90 litres (88 useable) just modifying the mount brackets with a 5-10mm packer. with this bigger tank, around town with the wife's foot pushed through to the floor, we comfortably get 460 kms from a tank of gas and generally 600kms on a trip without towing

regards Tony

[PradOz Advanced Member Find all posts View Profile Close PradOz]

Re: Petrol leak from dis-used filler pipe since LPG conversion

Hi Tony

What size LPG tank do you have to get 460km out of it? The LPG guage (old main petrol guage) is hopeless to check when to refill the LPG so you have to keep track of kms travelled. I would never get that distance out of my LPG tank and its a 72litre useable tank.

So just to check - you removed the old Prado 69 litre sub tank and replaced with a 88 litre Nissan Patrol tank? What year nissan is it from or will any year model fit? Any idea on cost just for the tank? I am guessing it was a secondhand tank? Any chance of posting a picture or two up here of it sitting under the prado

Does the fuel guage for petrol (old sub tank guage) still work accurately for petrol with a different tank or do you now measure kilometres to determine when to fill up the petrol? Any other issues or things to think about due to the petrol tank change? I suppose fuel filter is different, not sure what else. Thanks....

[Tony&Tracey Junior Member Find all posts View Profile Close Tony&Tracey]

Re: Petrol leak from dis-used filler pipe since LPG conversion

Hi Prad Oz,

as far as i am aware, the tank fitted is a current model Patrol tank, it is a 91-2 litre tank with about 85-88 useable litre of LPG. as i say, when i went to get the original install done, the mechanic, who was a customer of mine, suggested this tank and at little difference in cost. it was a new tank and install.all up install with tank and extra install mods was approx $3000 18 months ago.

the install was to remove the main tank, not the sub, and install the LPG at the rear as per normal. the guage is a bit average. from what i understand, very few of these conversions result in an accurate LPG guage. we do the same as you, watch the kms as a guide. in our case, when the gas tank full, the guage doesnt move for 100-120kms, then it operates normally, but the red dash light comes on at about 360kms and thats when i know i have about 100kms left, by trial and error. the tank itself doesnt appear to sit any lower than other standard prado LPG conversions, maybe just a bit longer.

gauge wise though, we use the standard sub tank guage and the dash guage (the old main tank) shows the LPG tank. the only other extra is the LPG / Petrol swap button when i want to drive dedicated petrol. as far as fuel filter goes, it should be all the same, the fuel from the sub is not touched at all and is factory. after all, the liquidified gas makes it way up to the convertor under the bonnet, as the name suggests this converts the liquid LPG into a gas and slightly pre heats it off frozen. from there, the gas is just piped into the air intake hose as normal air / gas mixture via the throttle body.

when it stops raining up here, yep the Sunshine Coast - not, i will get some photos orgainised

regards Tony

[PradOz Advanced Member Find all posts View Profile Close PradOz]

Re: Petrol leak from dis-used filler pipe since LPG conversion

Sorry Tony I misunderstood your original post. I thought you replaced the prado main petrol tank with a nissan petrol tank and replaced the prado petrol sub tank with a LPG tank. Now it all makes sense - sorry stupid me DOH!!! My LPG tank is about 72 or 74 litres (useable) but dont seem to be getting the economy figures similar to you. Its going back again next Tuesday to retune it and also look at this petrol leaking problem which i have no idea what we will do as i have no idea whats causing it. Would have loved a bigger petrol tank but sounds like you have the same as me a 69 ltre petrol sub tank. cheers.... PS- if you have any photos of the tank i will print and show my LPG mechanic next tuesday as it is always better to have a larger tank for the mileage you want to cover between stops and availability of LPG in some areas is non existant, cheers again....

[mike1100 Junior Member Find all posts View Profile Close mike1100]

Re: Petrol leak from dis-used filler pipe since LPG conversion

I have a Dec 1999 petrol/LPG Prado. After I fill up with petrol I find I end up having a small amount (cup full?) of petrol leak out of where the old main tank filler pipe was cut off. Not much you may say but enough to be a safety hazard. Dont want to go up in flames from someones smouldering cigarette butt or put up with the fumes in house from it leaking in the garage.

The main tank was removed when fitting the LPG tank. The pipe was sealed by a plastic cap and hose clamp by installer. I looked at someone elses recently and found theirs was done exactly the same and they were from interstate but they didnt have the petrol leak problem. I do know of others that had the same problem as me but not solved it. I only fill until the pump clicks off so its not an overfill issue. It happens after filling at different service stations so not linked to one servo. Didnt happen after LPG was first installed but has developed over last year to now always happen when filled or near filled. The leak is behind the left rear tyre. It doesnt happen immediately after you fill up, it happens after you drive. It makes me think fuel is going up the neck of filler pipe to my existing sub tank and then back down the old dis-used main filler pipe. If you look up under the car at this spot you can see the 2 fuel tank filler pipes and in my case where the pipe is cut off.

At Xmas I decided enough is enough when I could smell it leaking yet again. Simple enough job I thought so I bought some of the "knead it" type product for holes in petrol tanks etc and tried that. It just absorbed the fuel and allowed it to leak. I thought it was a faulty batch and removed it and bought another brand at another outlet/town. It also absorbed the petrol again allowing it to leak, and this time was leaking after driving around 150kms on petrol before I switched over to gas thinking this would stop my problem. I was wondering if there is an adhesive tape or bandage that will seal petrol if I wrap it over the plastic cap on the old filler pipe end? Or any other suggestions?


Some people have suggested that fuel automatically drains from either tank to the other as a fail safe mechanism built in by Toyota as suggested in this PP topic: http://pradopoint.com/viewtopic.php?f=15&t=4082

But no one has proven this to be true and even if it was wouldnt that cease after a correctly done LPG installation? See here where I have asked about this without any luck also: http://www.exploroz.com/Forum/Topic/752 ... Prado.aspx
It details that fuel does NOT purposely leak from one tank to the other.

There must be more than me on PP with this problem. I am not happy with the solution being I only part fill the sub tank as that defeats the purpose of having the full capacity. Any help or advice appreciated - cheers

Pradoz I have the exact same probelm when I fill out Prado up with fuel. It never did it when we had he conversion done, so I can only asume that the fuel had corrodid the plastic in some way. I tried tightening the clamp, which made no difference. There is a plastic cap in the filler neck to prevent use filling the main tank, but there must be a join between the two fillers somewhere for the fuel to get into the hose. I stop filling as soon as it clicks off, and would get @ half a cup full of fuel. Next service will take it back and see if they can do something. I also had the fuel smell which they fixed last time they serviced it. Not sure what they did though. Curious to know what sort of milage you get. I have a rola luggage rack and 265/75 tyres which have effected the milage, but we get @ 320km from 65 ltrs.

[PradOz Advanced Member Find all posts View Profile Close PradOz]

Re: Petrol leak from dis-used filler pipe since LPG conversion

Hi - I would get around same mileage when its running well. At the moment its running higher. It goes back in for rego check on Tuesday so will get it adjusted then. Have you ever had any issues with backfiring, even if its only once or twice? Where do you live? I am in south west sydney. The mechanic has said he will be doing a thorough search on the car to find source of trouble while i am there. Hope we work out why. I rang Toyota Friday looking for a Technical Division but only found out hat all technical information has to come from the local dealership, but they have access to a technical hotline. So all going well i am going to talk with my dealer nearby and see what we find out. Maybe worth asking some questions from yours too. Will post up any findings after my visit with my mechanic on Tuesday. Cheers

[PradOz Advanced Member Find all posts View Profile Close PradOz]

Re: Petrol leak from dis-used filler pipe since LPG conversion

I seem to have fixed (touch wood) the petrol leak from my old dis-used main filler pipe.

When i took the car to the LPG mechanic, he called his LPG supplier rep to check if there were any known issues with petrol leaks. He said there was a known 'minor petrol leak problem' in Prados. He suggested fitting a piece of petrol hose from as old main tank and put a welch plug in the open end and hold all together with hose clamps.

I wasnt too sure this could work as hose clamps didnt seal the last cap on there. We couldnt get any hose from an old prado petrol tank so fitted a piece of standard reinforced fuel hose. I think its about 40mm dia. It had to be heated up to fit the welch plug in it. A hose clamp was fitted on the hose over the welch plug and another one over the other end that slides over the dis-used filler pipe. The fuel hose would be about 80mm long.

So far it hasnt leaked and i have filled the sub tank to when it clicks off. So hope it stays that way now and i havent jinxed myself. cheers....

[brookseye Lurker Find all posts View Profile Close brookseye]

Re: Petrol leak from dis-used filler pipe since LPG conversion

Hi PradOz,
Just read all your posts on this issue, I have the same issue with my 98 Prado V6 on LPG.
Today we fitted the hose - 80 mm length with the welch plug and the hose clamps.. seems to be working so far.
I am curious to hear how yours is going, a year on down the track...