[Mk2] [Generic] Fuel Guage sender unit question

[Ken58]

Can anyone tell me, does the warning light have a seperate sender to the needle guage please? if the needle was stuck for instance ( it isn't, but if it was) would the light still come on when the fuel was low as per usual, or does it work on the needle position?

Thanks

[Lewis Jay]

Yes they are seprate, the gauge is done with a "float and arm" the light is done with a "ball in a tube thing".

Yes, if the needle and/or the "float and arm" was stuck the low fuel warning light would come providing the "ball" wasnt stuck too.

[Ken58]

Right thanks, I thought that was the case, I remembered reading something about it in a post on here recently, I was going to do a search, but when you do you get hundreds of posts come up.
Thanks again

[nigel_bytes]

Ive been having probs with my fuel sender too, What i did was to dismantle the fuel level float (will try and post some pics later) Now if you remove the cover from the float you will see an arm which sweeps across a coil (resistance wire) I simply used a needle file across the wire resistor, 3 ohms float raised 110ohm float lowered, This appears to have worked for me.

Its interesting reading threads on here that the low level warning switch next to the fuel level guage is some kind of ball which gets stuck.
After a lot of searching i have found that in fact it is not a ball at all.
Try doing a search for a fuel guage thermistor, You may recognize the illustration here,

http://industrial.panasonic.com/www-dat ... 000CE2.pdf

As a level gauge for infl ammable liquid used as fuel
for automobiles and other industrial equipment, this
detects the liquid level electrically by contactless
method with application of thermistor features, and
indication by lamp.
■ Operating Principle
While thermistor is immersed in a liquid, it has difficulties
to be self-exothermic due to heat discharge to the liquid.
Accordingly, the lamp is not turned on because of
high resistance value and small current fl ow. When
the thermistor is exposed to air due to decrease of
the liquid, it is abruptly heated, thus decreasing the
resistance value. At this time, large current fl ows
turning the lamp on.

All the best Andy.

[Ken58]

Very interesting, thanks for posting that. Incidently, my guage is working ok, when I fitted the cream dials I got the needle position slightly out ( will sort it at a later date) it's now three digits above empty when the light starts to come on.

[Moo]

Its interesting reading threads on here that the low level warning switch next to the fuel level guage is some kind of ball which gets stuck.
After a lot of searching i have found that in fact it is not a ball at all.
Try doing a search for a fuel guage thermistor, You may recognize the illustration here

I wondered about that too having fitted a new fuel sender a few days ago and not seeing a ball of any kind. Maybe it was the ball method on the earlier revs and was changed on rev3?

My old sender has 3 holes in the top and bottom of the bit that deals with the low fuel light. I assumed that when the level dropped below this bit the fuel would drain out of the bottom holes and then the light comes on.

That's just a guess though, not based on knowledge. The thermistor explanation does make sense.

http://www.imoc.co.uk/forums/viewtopic.php?t=120322

[nigel_bytes]

Mine is a rev1 import, Out of curiosity i purchsed a Mk 1 sender guage from ebay and it was exactly the same sender all be it the level guage was a differant height.

[nigel_bytes]

Heres the mark 2 rev 1 sender unit you can see the arm that sweeps across the resistor wire, i suppose that after 19 years and more it will have picked up a bit of dirt so a light going over with a needle file seems to have brought it back to life, The mark 1 is the same but the float has a differant height, Once again float closed 3 ohms, 110 ohms float lowered.

[Mr2_NA]

Submit that to the bloody knowledge base now!!!!!

Mine works

[Mike N]

My fuel level gauge does'nt work anymore - but the light does.

[toxo]

I wondered about that too having fitted a new fuel sender a few days ago and not seeing a ball of any kind. Maybe it was the ball method on the earlier revs and was changed on rev3?

My old sender has 3 holes in the top and bottom of the bit that deals with the low fuel light. I assumed that when the level dropped below this bit the fuel would drain out of the bottom holes and then the light comes on.

There's only 1 part listed in the EPC so I reckon they are the same across all revs. My understanding is that the ball type thing is inside that cannister with holes in, and floats inside it, so as the fuel level drops it bridges a connection at the bottom of the little cylinder. So, a working one should rattle - both shafted ones I have do not. I think the rubbish supermarket fuel I use has gunked up the inside of the cylinder thingy so that the ball can't move down in it.

Edit: Just read the thermistor post

[toxo]

It gets stranger!! I decided not to fill my car up today (am off the bottom of the fuel gauge) so that there isn't much fuel in the tank when I come to take the sender out. I was driving along on fumes and my low fuel light WENT OFF! WTF?! I can't have wired it in the wrong way around as the plug isn't reversible, but it is from a different car so could I have done something that means it's operating in reverse?!

[nigel_bytes]

It gets stranger!! I decided not to fill my car up today (am off the bottom of the fuel gauge) so that there isn't much fuel in the tank when I come to take the sender out. I was driving along on fumes and my low fuel light WENT OFF! WTF?! I can't have wired it in the wrong way around as the plug isn't reversible, but it is from a different car so could I have done something that means it's operating in reverse?!

If fuel were to Splash onto the sensor it will turn the red light off, If you were to remove the sensor and connect it outside of the tank and turn on ignition the sensor gets hot, thus it becomes conductive (this turns on the light) Now, When fuel touches the sensor it cools the sensor down making it non conductive (light out)
After years of use i'm sure they wont work as good as when new.

I tried contacting panasonic with a view to purchasing these sensors but they asked if i had a business account (I don't)

[toxo]

If that process works the same when dipping the sensor in a glass of water then I'll try that and see what happens. If fuel splashed it I'd expect it to go on for a few seconds then off again etc... this was just like a switch. It wasn't intermittent, it seriously just seems to work like it's in reverse.

[nigel_bytes]

If your testing the sensor don't try it in water,
When you car moves the fuel moves about in the tank so it will always splash against the sensor, However there are a few seconds delay, Same as the fuel guage, Thats in theory but as i have said, These sensors are getting a little old now and just like any other electronic componant their values change over the years. Mine does the same, but i do get a warning light for a few seconds when the level drops so i know i'm close to empty.





all the best Andrew

[Awilkinson75]

When i fill the car up the fuel gague wont go all the way to the top and also takes an age to move up, how can i fix the gauge so it will go all the was up? also how many miles should i be getting to a full tank? im getting about 220 mile to a tank but im sure my old MR2 was around the 300+ mark, what should it ba and again how do I fix thi problem? Many thanks

[Barnz]

When i fill the car up the fuel gague wont go all the way to the top and also takes an age to move up, how can i fix the gauge so it will go all the was up? also how many miles should i be getting to a full tank? im getting about 220 mile to a tank but im sure my old MR2 was around the 300+ mark, what should it ba and again how do I fix thi problem? Many thanks

Hi sorry to drag this old post up did you get this sorted? I have the same problem where my needle only goes to 2nd/3rd mark from top when tank is brimmed
Cheers

[Moo]

Have you had the needle off the gauge at all?

[Barnz]

Have you had the needle off the gauge at all?

Nope still has std gauges - JDM 110 mph. Dash only been out when changing dash lights, but it was doing this before I changed those.

[Neptune]

i have gauge issues too, full tank - gauge only goes half way up, but the gauge does work when it goes below half a tank, and the low fuel light works...

ive replaced the sender with a new one, but it still only goes half way when full.

any ideas?