Petrol leaking from old dis-used petrol filler pipe in my LPG Prado

Submitted: Saturday, Jan 16, 2010 at 12:27
ThreadID: 75253 Views:3130 Replies:3 FollowUps:8
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Looking for advice from anyone with LPG fitted on a 90 series Prado. Can you read this and then look up under yours behind left rear tyre and see what your installer did.

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. 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 another person that had the same problem as me. I only fill until the pump clicks off so its not an overfill issue. 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. The leak is behind the left rear tyre but doesnt happen immediaely after you fill up, it happens after you drive. 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.

Any help or advice appreciated.

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Reply By: Tenpounder (SA) - Saturday, Jan 16, 2010 at 13:03

Saturday, Jan 16, 2010 at 13:03
Hi PradOz. I have the same model, but petrol only. As well as the two filler pipes, the 90 series has an interconnecting pipe between the two tanks. It sounds to me as though the interconnecting pipe is still in place in on your vehicle, allowing the fuel levels to equalise to some degree (as it was originally supposed to do, to keep both pumps lubricated).
If I am right, the obvious thing to do is to block off the equalising pipe.
AnswerID: 399718

Follow Up By: PradOz - Saturday, Jan 16, 2010 at 13:16

Saturday, Jan 16, 2010 at 13:16
Thanks Tenpounder you have just confirmed what I have thought and even spoken about. Where is the interconnecting pipe? How do I find it, recognise it etc?

I was even told there couldnt be an interconnecting pipe when I mentioned this to the LPG installer over a year ago. He said he had never heard of it but i had heard about it 10 years ago when i first bought it. I was told back then it was to prevent either fuel tank running empty.

Thanks again

FollowupID: 668683

Reply By: Tenpounder (SA) - Saturday, Jan 16, 2010 at 13:57

Saturday, Jan 16, 2010 at 13:57
Hi there. I have checked my workshop manual. There is no separate equalisation pipe. Sorry.
The supply pipe runs from the main tank to the changeover valve under the second tank, so this suggests there is a permanent bypass in the valve body to allow equalisation. Looking at the pictures, there are THREE pipes that must be blocked off where they enter the original main tank, that's the supply pipe, the vapour pipe and the return pipe. You would have to hope that the fuel system is properly vented back to the remaining fuel tank, and that any fuel return is also routed to the remaining tank.
Incidentally, I was made very much aware of the situation at Christmas, when I fulled the second tank first, and managed to refuel BOTH tanks via the second filler. I was wondering why it was so slow, and then I got suspicious when the second tank seemed to be taking over 100 litres!!! So there definitely IS an interconnection whch bypasses the changeover valve.
I hope this helps.
AnswerID: 399725

Follow Up By: PradOz - Saturday, Jan 16, 2010 at 14:18

Saturday, Jan 16, 2010 at 14:18
Thank you. Any chance you can post a copy of the pictures on here or scan them and email to me to: v8footy(at)hotmail(dot)com

Funny how you and I both originally thought it was the same thing with a separate equalisation pipe. Now I am not sure about solving my problem. Like I said earlier I know one other guy with exactly the same problem. Thanks again

FollowupID: 668690

Follow Up By: Tenpounder (SA) - Saturday, Jan 16, 2010 at 14:21

Saturday, Jan 16, 2010 at 14:21
Yes, I'm happy to try to scan and forward to you. My interpretation is that, at least, you need to ensure the supply pipe at the main tank connection is properly sealed off. But also, it seems possible that surplus fuel could be returned to the main tank connection, and then be allowed to run free, unless it had been properly blocked off too.
FollowupID: 668692

Follow Up By: Tenpounder (SA) - Saturday, Jan 16, 2010 at 14:47

Saturday, Jan 16, 2010 at 14:47
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FollowupID: 668696

Follow Up By: PradOz - Saturday, Jan 16, 2010 at 14:50

Saturday, Jan 16, 2010 at 14:50
Thank you
FollowupID: 668697

Reply By: Wherehegon - Saturday, Jan 16, 2010 at 20:38

Saturday, Jan 16, 2010 at 20:38
I had exactly the same issue and so does my neighbour up the street and anothe bloke I know, set up the same as yours, mine had a yellow cap on the end of the main tank filling hose with a clamp. When I rang up and asked why I literally had fuel leaking onto my garage floor and I mean not just a drip I mean dripping quickly like a tap not turned off properly. My reply was DONT fill the reserve tank to full only 3/4. This allows for expansion in the sub tank. I said you are kidding me arn't you ?? He said no and every 90 series prado is fitted the same way. The fuel will pressurise in the reserve tank and come up the filler neck and go accross into the main tank hose causing the drip. He was right as when I filled it to 3/4 no issues, fill it full to first click of pump and it would leak. I even rand the RTA to see if this was correct and they didnt want to know about it, go back to installer, 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. It was a person on here that recomended him but that not their fault, maybe they got a good job. Regards Steve
AnswerID: 399776

Follow Up By: Wherehegon - Saturday, Jan 16, 2010 at 20:40

Saturday, Jan 16, 2010 at 20:40
I should mention also this was related to hot weather, anything over 30c. Cold days was fine
FollowupID: 668730

Follow Up By: PradOz - Sunday, Jan 17, 2010 at 16:34

Sunday, Jan 17, 2010 at 16:34
Hi - hope i wasnt the one who recommended the installer - Mine was in Sydney and my filler pipe has the same yellow cap and hose clamp. The other one I seen on a guys from QLD had a red cap and his didnt leak - maybe I should change colours ;) Where was your installation done?

I havent checked out for the other issues you mention but will have to now for peace of mind. I dont have the smell coming into the cabin but it certainly drips like you mentioned.

You have got to wonder why they dont put a hose on the end of the old dis-used main filler pipe and loop it back into the line to the sub tank. I dont know enough to know if it could work or be done.

I am still uncertain if i would go LPG again. In the same vehicle NO as I am disappointed I lost the main tank rather than the sub. I am sure another shape and brand LPG tank would have fitted in lieu of the sub so i could have kept the main. 3/4 fill in the sub isnt good as it would be just under 52 litres which isnt much in the vehicle of this size, especially when towing.

I am not happy with the fuel economy on LPG as I think it should be around 20 litres/100 and I am more like 23 despite being on top of tune ups etc. I am thinking of taking to someone else just to see if i get better after they look at it. What economy did you get? I have no issue with power, but did have issue with back fire twice. One time it blew up the air box requiring it to be repaired. Hopefully the change in plugs and leads will help. I think mine is more a problem in hot weather too now you mention it. I thought after i filled it to the click last time and then immediately drove 150kms it wouldnt happen, but it did that night. Thanks for your comments....
FollowupID: 668886

Follow Up By: Wherehegon - Sunday, Jan 17, 2010 at 17:35

Sunday, Jan 17, 2010 at 17:35
Wont mention the name but it was done in the suburb called Prestons ??? NSW, I always wondered myself why the main line off the main tank was not looped back into the reserve filler line as you have mentioned, would have solved the issue, must be a reaon why ?? You are getting identical figures I got with mine, 23 around town, I think freeway for memory was 15?? When towing I found it gutless and I ran it on LPG on Stockton once, wholey hell, no power and I reckon it was using around 35L absolutely drank it. I had it back fire twice and both times was under extremely heavy braking (abs cut in) some one pulling out in front of me and it stalled on both occasions, dangerous when I needed to get going again. I wont have it again unless factory fitted. I have diesel 90 series now and have no intentions of bothering to put it on LPG to gain a bit of extra power, if I need extra grunt I will chip it and do the exhaust. You can pm me with your ph number or if not a member eamil me your ph number and I will ring you and have a chat to you about if.......Regards Steve
FollowupID: 668912

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