GUIV Fuel gauge has false reading

Hey guys,

so the mighty GUIV is now relegated to being driven by the wife as a daily which is Ace cause it will keep the Kms down on it. Freeway commuting kms SUCK.

I drove it on the weekend and noted that it needed a fuel up but didn't get around to it. the full light was on when i pulled in the drive (I know I know, i should have sorted it... but i didn't).

Today Naomi was driving the daughter to daycare around the corner and it cut out. She had trouble starting it and ca led me, it turned over a heap then fired so she got in and drove while i was on the phone. It was sluggish then stopped and she parked it and walked.

Sat there all day as i was in Melbourne. Got home tonight and tried it, primed it and after a bit got it going for 10m then done. Ended up on a tilt tray back home.

So talking to Naomi trying to figure if she had got some bad fuel somewhere?? the gauge was showing 1/4 of a tank......

NO WAY!! when i got it home i started at the fuel filter and checked for prime then supply and clearly it was empty. 20t jerry later and its good to go.

SO! Bloody thing! i have filled it up and filled the Sub, i have always filled both and Always wait for the light to come on the pump the sub and empty both tanks every cycle pretty well.

What can i check guys?

Umm, I don't read a problem there? Did you miss something out or am I misreading it?
The car was low on fuel, not filled up, then it ran out?

Nah sorry i Rambled.

Car stopped on the side of the road. Fuel gauge read 1/4 of a tank. Naomi thought i put fuel in it, i thought she did. neither of us did! the fuel gauge got excited all by itself!

Thats what I read as well Winnie...

Dunno if it means anything but i had a GQ petty that had a dodgy main tank wiper and at about 1/8th would go back to 1/4 ish for a while then drop to 1/16th ish... the fuel light always worked as advertised tho

The old husband and wife blame game ....mate you cant win , you know its your fault .haha .

Yeah its Odd, as i said i have always run from full to fuel light and always use both tanks. the rear tank is an LRA 147lt. Never had a problem before? I use the Odometer to measure fuel usage too and it was where id expect it to run out but the gauge told me that the missus had fuelled it for sure.

It's a GU, bet the earth for the fuel gauge is high resistance somewhere. Trace track and clean wire connectors. Just GUessing.:biggrin:

When the light comes on to show you are on reserve ,,how many K's can you do.
Having a LRA tank the sender may not be as accurate as you think.
My 75ltr AUX is the same when talking to Kevin at Brown Davis he said
the sender is adjusted to neg off when empty.

I think the reserve light may have been on longer than what you think
and no one noticed.

That's the thing, the light came on on the weekend for me. When it stopped the light was off and the gauge showed a 1/4 tank so we pty thought the other had put some fuel in it.

4 days from monthly payday and I ain't putting $200 or diesel in it normally.

hopefully the tank is clean and you havent sucked up any gunk,
I transfer fuel well before the light comes on.

Quote:

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Originally Posted by threedogs

hopefully the tank is clean and you havent sucked up any gunk,
I transfer fuel well before the light comes on.

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That is a comment that has always puzzled me (not having a shot TD as you see it heaps of times by lots of people)...

The fuel pick up is in the very bottom of the tank in a little surge baffle thingy.
I've always wondered how does running the level of fuel down suck up anything extra over what would have got sucked up anyway... if you get my drift.
The only thing that should get sucked up is any floating gunk or 'lighter than fuel' contaminants such as some of the ethanes.

One would think rust, dirt, grit, scale or particulates etc in the tank will all sink and find their way into the pick up in pretty short order.

Most of us run our Subs to dead empty so why wouldn't it be OK to run the main to the low light.
That is what I have always done on my 4X's

For the fuel gauge to be reading higher the resistance in the fuel gauge circuit needs to reduce (unless the alternator is overcharging.....even then it's not likely). So I can't see it being an earthing, wiring or connector problem.

What I think has happened is, due to the aftermarket fuel tank and the fuel level being so low that the fuel float may have been out of the liquid. This has allowed the fuel float and arm to bounce around excessively and the float may have become stuck on something in the tank.

I would just fill the tank and see if the gauge reads full. If the float is stuck hopefully this dislodges it. Then just drive it and monitor it. You know how many Ks you get out of your main tank so you will be able to tell really quick if the fuel gauge gets stuck at a quarter tank again.

If the gauge is stuck at a quarter tank then you will need to remove the sender unit and check.

Agree with Rodney...
Bad earth is a fault that would extinguish low level light so possibly explains that but then the gauge will read less than actual so doesn't explain that...
Stuck sender explains the gauge but possibly not the low level light

Drop some motion lotion in the sucker and see what happens...

yeah cheers guys, that did cross my mind too to be honest as its just a float so i have filled the tank and will run it to the light comes on as i will have the Sub full next time if it leaves me stranded. Thanks for your help. I will let you know for sure.

Yep also agree with rod..
When my float arm parted ways it read guess what.... 1/4 tank..
I'd be pulling the pic ups out before filling em bloke..
That way you can check earth points to..
(Bugger, just read you have filled em)

Here is an awesome set of pics of your sender, yes its an Ebay listing... (thanks steve coogan whoever you are)
http://www.ebay.com.au/itm/Nissan-Pa...8AAOSw-yxU3AN1

The green thingy is the fuel pick up and sits right on the bottom of the tank.
It can slide (but not easily) up and down so it can be adjusted for different tanks

The silver cylinder thingy on the seperate mounting rod with the yellow wire is the fuel low level light switch
They are a bit of a strange critter on how they work and when there was bugger all fuel maybe it got confused

The other pics are close ups of the wiper arm and resistance strip etc for contents gauge.
Perhaps when it was dead empty the wiper was at a point on the resistance strip it hadn't ever been before so the gauge went to a happy place sama sama as when the float falls off.

http://www.nissanpatrol.com.au/forum...015/11/140.jpg

http://www.nissanpatrol.com.au/forum...015/11/141.jpg

http://www.nissanpatrol.com.au/forum...015/11/142.jpg

http://www.nissanpatrol.com.au/forum...015/11/143.jpg

http://www.nissanpatrol.com.au/forum...015/11/144.jpg

Nice find ET


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