1997 Prado - Duel Fuel - Issues with running on petrol

[Chris1234 Lurker Find all posts View Profile Close Chris1234]

Hi guys,

i have recently had issues with running on petrol, following some months of running only on LPG.

Has anyone had any issues like this and what was the resolution to get it running on petrol again? Petrol filter, petrol pump, injectors, etc?

Any assistance would be greatly appreciated.

[tassie tiger Advanced Member Find all posts View Profile Close tassie tiger]

Sounds like a timing issue. I would check that first.

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

Probably find the injectors have gummed up from lack of use. Wont be timing as they have a base timing set then the computer does the rest and this wouldnt have been changed to run LPG or petrol (there only a venturi system on the 95's not injected like the 120's). I hated my 95 on gas, worse bloody thing I did. Piss arse small tank (forever filling up) slow filling LPG at some servo's, then had issues with petrol vapour's extremly bad especially on a hot day if I had the reserve tank full it would come back up the filler neck back across into the hose that went to the main tank then would literally drip raw fuel on the ground. 3 prado's I looked at all different systems but did the same thing rang rta etc no one wanted to know about it which suprised me with the RTA the installer moved but it wasnt the instalation it was the way the kits are supplied. A member on here had the same issue but modified it. You will find you will probably need to remove the injectors and have them cleaned OR run a can of ramflo direct through the injectors (needs to be done by mechanic) cheapest option. Might pay to check the fuel in the tank if you havnt use petrol for so long may have a heap of condensation floating around in the tank, drop some metho in it to absorb the condensate.Cheers Steve

[ken2m Junior Member Find all posts View Profile Close ken2m]

The fuel in the tank may be stale especially if it happens to be E10 (E10 lasts for about 4 weeks before octane rating drops significantly). The way I have run mine is to run on gas until motor stops reving above about 3500 rpm then switch to petrol, run for a while (10km or so) then fill with gas and change over. Always run with about 1/4 minumum petrol not E10 and add injector cleaner to all petrol at about double the minimum recommended strength ie: if it treats a full tank only half fill the tank. E10 is ok to use only when you are going to use the full petrol tank in a short time.

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

Interesting about the E10 Ken, didnt know that, mind you I dont run either of my cars on that crap, for the few cents you save but use more per 100k not worth the damage I reckon it will cause long term like stuffed injector seals, rubber fuel lines getting eaten away internally. my mates works for Holden and reckons that E10 crap is eating injector seals in commodores like theres no tomorrow. Cheers Steve

[ken2m Junior Member Find all posts View Profile Close ken2m]

I think but am not sure that the moisture absorption is the main problem.

[williade Avid PP Poster! Find all posts View Profile Close williade]

Sounds like a timing issue. I would check that first.

I think Tassie is on to something. The ignition timing could have advanced significantly beyond what is safe for Unleaded. As I understand it (maybe and expert can correct me here) LPG has an equivalent octane rating of 105-110, much higher that of the best Unleaded Petrol so it may run smoothly on LPG with the timing having advanced.

I know some dodgy LPG fitters who advance the distributor timing to make the LPG run smooth at the expensive of pinging when using Unleaded. But the 3.4L V6 uses electronic ignition so the timing would only be wrong if there was a problem elsewhere.

Perhaps the knock sensors are cactus and the ECU has continually advanced the timing because its has no feed back from the knock senors.

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

You cant adjust timing manually on prado, it is computer controlled

""The higher the fuel octane rating, the less prone it is to detonation, hence the greater potential for ignition timing to be advanced further. – Again resulting in higher efficiency. However, we have no control over the ignition timing advance as it is adjusted by the engine management system.""

Cheers Steve

[williade Avid PP Poster! Find all posts View Profile Close williade]

Yes, the timing can't be advanced manually. But a failed knock sensor could cause to the ECU to continually advance the timing.

Another possible cause for it to run rough on Petrol is if there is an air leak somewhere in the induction system that was present when the LPG was installed. The LPG fitter would have adjusted the LPG fuel air mix to compensate for the leak so it runs smooth on LPG.

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

If there was a leak in the induction system there is no way in the world the LPG will run, try even cracking the air cleaner open just by releasing the clip and it will stall , same if you have a snorkel fitted. if it doesnt have a balance tube between the air cleaner and mixer it will either not run at all or blow the the lid clean off the airfilter due to back fire or rip a hole in the rubber induction hose (the flexi one) and when they go off, it sounds like a bomb under the bonnet let me tell you, you know about it lol scares the bejesus out of you. You can check the knock sensor if you know how to use a multi meter.. The timing on a prado is that slow to advance its not funny Im talking 3000klms of running premium unleaded before the computer will go ""oh were running a higher octane fuel lets sloooooowy increase the timing"" Thats why some people put premium fuel in use it for a tank and go thats a waste of money and go back to normal unleaded, if you run it for roughly 3000k plus then you will start to see results. I remember reading a full article about the fuel usage,types,LPG etc on the 95 V6 prados before I had myn put on LPG, still wouldnt have it again. If I still wanted to go 4wding but was concerned about excess fuel usage Id buy a suk jimny before i go LPG again. I had issues with myn and has turned me against it. Plenty of people run it and dont have any issues.Cheers Steve

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

I've got dual fuel on my 90 and as Steve said if you get a backfire and blow the lid of the air cleaner off, and yeah, you know all about it! You don't go anywhere on lpg until you reclip it shut.
The backfire has only happened 3, maybe 4 times to me and my mechanic made a few adjustments and no worries. Except for one time i had to hit the brakes HARD and that popped the air cleaner.
I always, always switch to petrol for about 20k's after every tank of gas. This should help keep everything working properly.
True, you go to the servo more often but that doesn't worry me in the slightest. Even driving up the Stuart Hwy i filled the sub full but only needed a bit of it when we went remote.
Being that the system only cost $500 after getting the rebate it has well and truly paid for itself. Am i glad i did it? Yes, but only in metro. We had applied for a remote job, didn't get it in the end :twisted: and i would have gone back to 2 petrol tanks.

Cheers
John

[Chris1234 Lurker Find all posts View Profile Close Chris1234]

Thanks to all of you for your comments and extensive information about possible causes. Much appreciated

[Chris1234 Lurker Find all posts View Profile Close Chris1234]

Thanks Steve M. I will definitely try this option first.

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

Lets us know how you go when you get it fixed would be great to know what the issue was. I may be proven totally wrong and be a timing issue (been wrong many a time lol) But for the sake of anyone else that may have the same problem it will give them some thing to look at...Cheers Steve