Fuel Gauge Problems After LPG fitted

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

I have been to Steens , Clive had a play with my gauge , still reads half when full. Good place though at least he listened and had a look.

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

An update for all.
I just got back from holidays in Darwin - Very nice up there... I should still be there but finances won't allow such luxury's.

Anyway the Prado has been back to the auto electrician's once again. This is their 3rd go at fixing it.

They have put a 47 Ohm resistor somewhere near the sender unit of the main tank, under the 2nd row seats. As this was done on friday just gone its a bit hard to know exactly how accurate things are as of yet, however, I believe that when the fuel light comes on it does mean that you need to fill up. This is in contrast to previous, where the light came on early and you had ages before needing to fill up.... However, the gauge only shows just over 1/4 and I have around 50 liters in the tank. So clearly I still have the problem of a full tank only showing as 1/2 full on the gauge.

At this stage I am not sure the people working on this problem (Auto electrician's) know what they are doing. I certainly don't know - but that goes without saying as I"m first to admit I'm a novice at electronics.

I do, however, have an extract from the manual showing the wiring of the Sender unit. I think I'm starting to understand some of the "workings" so may start some experimenting myself. (Hope I don't break it for good)..

One point to those with similar problems, My 90L light has never worked since the modification (Gas install). It appears that those who have working gauges and have Gas installed have a functioning 90L light ?

- - - Would a blown 90L bulb effect the gauge in any way - It is a bulb isn't it - not an LED. Just guessing.. Has the bulb blown ?

Also - Anyone reading who has Gas installed and a working gauge - please confirm that your 90L light is always on ?

** Also - if possible, the installer of your Gas system.. As I am at a point where I am willing to ring / talk to anyone who has successfully converted the Prado to Gas and has kept the Gauge working.

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

Hi tkstrong
I had my gas installed Oct 07 and the petrol gauge works as it should (indicates full when full and empty when empty).The 90L light is always on.Mine was installed by The Car Clinic in Brisbane.

[Zapper Member Find all posts View Profile Close Zapper]

Gas is now installed and fuel gauge is working as it should . The tech that did the install had already left so I couldn't get the information on the mod that was performed to get the guage working. I will ring them later today and I've a talk with him and see what he did.

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

Ok - Just another update:

Had a chance to test out the car fuel gauge. It seems that even though the Auto electrician feels the issue was fixed, it is not.

Somehow we are back to the original configuration.
Empty = Empty
1/2 = Full.

Currenty there is a 50 Ohm resistor being used.

I also dug out the old fuel tank and took some readings. "raydes" has already done this and my findings were just the same - as one would expect.

Original Tank says..
5 Ohm = Full
50 Ohm = Empty

Where to go from here I'm not sure. I performed some further tests as I purchased a whole bunch of resistors. I tried a 60 Ohm resistor which simply reduced even further... the range of the gauge.
For example, I know I have 1/2 a tank of fuel. 60 Ohm resistor showed 1/8th of a tank... which gave me 1/4 = full and empty = empty.

IMHO - and it is just a guess.. I think "raydes" is correct in saying that the issue is possibly pointing to the computer. Is the computer registering a fault code that is causing this issue?

From what I can tell, others on this forum have had "working" gauges and after a time, for no apparent reason, the gauge has stopped working and exhibits the same problem as I am experiencing... hence (computer fault?) Also - from what I can tell, my setup is the same as others - i.e. Resistor is the only thing used to correct fuel gauge.

Well - I'll keep working on it. Not sure where to go from here. I have no way of looking for computer fault codes..
I'll call back the Gas Man and Auto Electrician today..
Wish me luck..

[Zapper Member Find all posts View Profile Close Zapper]

tkstrong you are having no luck there,mine has the 60 ohm installed and works fine :shock: . Before you go down the computer track, might be worth while tracing the wires back and make sure they didn't get damaged during the install. It is a long shot but you never know sometimes faults like this turn out to be something simple in the end.

[jeremy Lurker Find all posts View Profile Close jeremy]

no news tkstrong??

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

Re: Fuel Gauge Problems After LPG fitted

I had the battery out of my car today ,for about an hour I also had the earth lead off the front inner guard . I refitted the earth lead and battery and took a few fuses out and refitted them while checking to see which are live with the ignition on . I had the car back together and started the motor ,reset the windows and put the code back in the radio and noticed the green 90 litre light was on ( it has not been on since gas was fitted in Feb ) the gauge also was reading 3/4 full ?????? Who knows, could have been just a bad earth on the guard .