M35 Fuel Gauge

[scotty nm35]

I have noticed sometimes the fuel gauge in my car drops from 1/4 tank to empty with the light on, in the space of a few k's. I read the v35's are having similar issues and wanted to know if anyone else has this problem.

I pulled the pump out to check but couldn't find anything obvious wrong with the sender resister.

[Jetwreck]

lol....yeh I get that when I have a bit of a play around tight corners......drops rapidly then slowly goes back up!

[iamhe77]

In the space of how many km's Scott?

Mine goes from 1/4 to light on after ~140kms normal driving

or

1/4 to light on after ~70-80kms of fun driving

I have noticed at times that the light will be on when I shut the car down, then an hour or so later when I go out again I will have just over 1/8 of tank left with no light on (nor does it come on for a while either).

Can also behave differently on different fuels.... Vpower will drop from 1/4 to nothing much faster than Ultimate.... and don't get me started on Vortex98

[andy65b]

It goes down fast at the end of the tank and probably does exactly the same thing. I am not that worried as I just fill up when the light comes on.

Cheers

Andy

[pixel8r]

Mine fluctuates the whole time, not just below the 1/4 mark. It can be below the 3/4 mark and then 5 minutes later its showing just above it...

I've learnt not to pay that much attention to it - since its usually just a "rough indication" rather than an accurate measurement.

Lately I filled up when the needle was just above empty (as in very very close to the empty line), but only got 54L in. Other times its been on the empty mark and I've managed to get around 62+L in.

From 1/4 to empty I normally get around 50-80km maximum.

[Angus Smart]

I've had mine go from 1/4 to light in a mater of 25 minutes of driving from my house (Bankstown) to oatley for gym..

with some spirited cornering

then back up to 1/4 if i drive home behind grandma

[Angus Smart]

It goes down fast at the end of the tank and probably does exactly the same thing. I am not that worried as I just fill up when the light comes on.

Cheers

Andy

I tend to not pay attention to light unless i am over 400km's in that tank haha.

[scotty nm35]

Mine drops to light on sometimes after one boot onto the freeway then stays there. If I switch the ignition off and on, its back up to where it was.

Im guessing there is a dry solder joint there somewhere, anyone know where the electronics is for the sensor? Let me guess, dash out?

[Cephas]

Mine drops from full to 2/3 very fast, then takes ages to go the rest of the way.

[euroequip]

Mine drops from full to 2/3 very fast, then takes ages to go the rest of the way.

So glad I found this thread. Here I was thinking it was just a thirsty beast... which it kind of is

[Cephas]

oh don't worry, its also a thirsty beast

[pixel8r]

Lately my fuel gauge has been getting much worse. Rather than giving me a pretty close "ballpark" reading, its now often wildly inaccurate. I've seen it nearly at the half way mark after just 130km or so, then I'll actually manage somewhere near 200km before it goes below the half way mark, then later it could be back up between 1/2 and 3/4...its just all over the place, often out by more than 1/4 of a tank!

Not sure if its just a faulty sensor but its very annoying. Soon I'll be using the kms since last fuel stop to determine how much fuel is in the tank...on a 2003 model car!!

[Angus Smart]

after fixing my turbo pressure pipe. i have been clocking 500km's easily in the volvo..

and this is with the same thirsty driving i was doing when i was getting 400's if not more pedal now i have more boost

[scotty nm35]

Lately my fuel gauge has been getting much worse. Rather than giving me a pretty close "ballpark" reading, its now often wildly inaccurate. I've seen it nearly at the half way mark after just 130km or so, then I'll actually manage somewhere near 200km before it goes below the half way mark, then later it could be back up between 1/2 and 3/4...its just all over the place, often out by more than 1/4 of a tank!

Not sure if its just a faulty sensor but its very annoying. Soon I'll be using the kms since last fuel stop to determine how much fuel is in the tank...on a 2003 model car!!

I sometimes get that, seems to be the carbon on the sensor wearing out as I pulled it out for a look. If you switch the ignition off and on, it goes back up to where it should be.

I wonder if you can buy the liquid carbon and repaint it...

Edited January 27, 2010 by scotty nm35

[pixel8r]

after fixing my turbo pressure pipe. i have been clocking 500km's easily in the volvo..

and this is with the same thirsty driving i was doing when i was getting 400's if not more pedal now i have more boost

?? what pipe is that?

[Angus Smart]

?? what pipe is that?

rubber hose near washer bottle to plenum area..

[pixel8r]

rubber hose near washer bottle to plenum area..

You mean the one that goes to the boost sensor (ie. the sensor in the little oval shaped black box that sends the boost readout to the in-dash guage) ?

Interesting, I fixed that sensor a few months ago after reading how to do it on here (power connections inside it needed re-soldering) but at the same time the factory hose split and continued to split every time i cut it and re-attached it...so I've replaced it with a similar sized hose but this one keeps falling off the plenum side since there's no "lip" to hold it on. Its been bothering me in the back of my mind ever since (ie. vacuum hose off cant be good) but I just haven't gotten around to fixing it since it didn't seem to upset performance.

Now that you mention it the fuel economy could well have started to go bad around the time I fixed that sensor...was getting mid 12's (L/100km) and now its consistently in the high 13's if not low 14's...

If thats all it is then I feel a bit silly for leaving it so long...

[scotty nm35]

Im guessing Angus means the 60mm black rubber pipe with the bend next to the washer bottle.

The hose you are talking about, the 3 or 4mm one will need to be replaced on most of the M35's coming in as they are very brittle. It only affects the boost meter in the dash so im not even sure all M35's have it. Definitely wont be the source of your bad economy, probably the heat doing that as the ecu is adding fuel as the inlet temps go up I think.