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Post by Colin McA on Mar 2, 2010 10:47:56 GMT
Couple of quick Q's for you all.
When there is not enough fuel in my car to run on the main or reserve line my gauge shows just under a 1/4 full.
The Voltage regulator is a new electronic type.
I have checked the circuit by trial fitting another gauge and this reads the same.
Is this normal or does my sender need adjusted?
I am also looking for the ohms of the sender when full, empty etc.
Thanks
Colin
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Post by Deleted on Mar 2, 2010 13:36:13 GMT
When mine was empty it showed empty. The guage was not extremly accurate but never almost quarter of a tank adrift.
Best of luck! Got a jerry can as well I hope!
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Post by chazmac on Mar 2, 2010 15:25:58 GMT
Sounds like great fun Colin. NOT My fuel gauge for what it is, is pretty accurate. When the tank is empty the guage shows empty. However there is definately something wrong with the speed with which it goes from full to empty haha  ) By the way I will have a rear heater control but god knows where. Sorry for not replying but bloody busy this weather. Not even seen mine for ages!!!! Well thats a fib I did check it was still there last weekend. ARRRGGHHHHH Started the Mk2 two weekends ago needed new plugs as they were grotty. My own fault as Jamie Gibbon told me to put long reach plugs in as the car would run great but that they would eventaully foul and need regular replacement. That was 4 years ago DOH. Anyhow car loves its new fuel filter and plugs and loved its run round the west end of glasgow. It's now ready for my cousins wedding on the 2nd of April. chaz |
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Post by johnwp5bcoupe on Mar 2, 2010 17:17:50 GMT
Couple of quick Q's for you all. When there is not enough fuel in my car to run on the main or reserve line my gauge shows just under a 1/4 full. The Voltage regulator is a new electronic type. I have checked the circuit by trial fitting another gauge and this reads the same. Is this normal or does my sender need adjusted? I am also looking for the ohms of the sender when full, empty etc. Thanks Colin Have you checked the voltage Colin? is it 10v? I have a rheostat in my spares I will measure it later for you. |
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Post by johnwp5bcoupe on Mar 2, 2010 17:23:26 GMT
I just checked Colin 20 Ohms to 240 Ohms  |
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Post by Colin McA on Mar 2, 2010 18:14:53 GMT
John,
Was the range just the gauge or was that the resistance from the sender?
I have been off this afternoon so gave it a quick check and was reading around 90ohms.
I have put a couple of gallons in so will give it another check.
Chas,
You better get stuck into the P5 and make sure it is ready for the SARR....
Colin
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Post by johnwp5bcoupe on Mar 2, 2010 18:21:02 GMT
Hi Colin that is the range of the rheostat/sender so at 90 ohms you should be reading about 1/4 full  |
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Post by Colin McA on Mar 2, 2010 18:30:34 GMT
Interesting.... The fuel level was def low.
I usually check for low fuel by looking at the fuel filter. if it is below the seam then it is normally too low to fire up.
Further investigation required here.
Cheers
Colin
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Post by Phil Nottingham on Mar 2, 2010 20:14:38 GMT
Senders are very rarely accurate and scale is not linear - even if they say Empty when empty they may not read Full when it is - or vice-versa! The float arm can stick or it may have been bent. Easy to remove and also the actual tank level can be dipped
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Post by johnwp5bcoupe on Mar 2, 2010 21:13:10 GMT
For test purposes Phil the Tank Sender well at least the one I have is Linear or as near as can be not Logarithmic. |
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Post by Phil Nottingham on Mar 2, 2010 22:17:05 GMT
Its electrical scale is linear as far as the resistance is concerned but the tank volume is not because of its shape. It measures fuel level not fuel volume - half full is not halfway up the tank even ignoring the dead amount that is not reached by the pickup. The scale attempts to correct this
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Post by mcgill on May 29, 2011 19:46:21 GMT
IF i connect my fuel gauge sender wires together,should it shoot to Full ? im sure i did this before and it went up,not going up now though  |
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Post by johnwp5bcoupe on May 29, 2011 21:20:53 GMT
It should go full scale if you short the Green and Black to Earth as long as you have your 10v on the other side (Light Green)
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Post by Deleted on May 30, 2011 9:44:15 GMT
The fuel guage works on heat , so as to smooth out the readings , if it were purely electrical it would bounce around as resistance varied - the coil retains heat for a time period ,so even if the current varies the needle doesnt
This means at full levels the heat is greater than at low levels so the guage tends to remain at full levels for longer then more rapidly fall at lower levels
linear sender but less so with the guage
the important point is the empty level !!
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Post by johnwp5bcoupe on May 30, 2011 9:57:29 GMT
The fuel guage works on heat , so as to smooth out the readings , if it were purely electrical it would bounce around as resistance varied - the coil retains heat for a time period ,so even if the current varies the needle doesnt This means at full levels the heat is greater than at low levels so the guage tends to remain at full levels for longer then more rapidly fall at lower levels linear sender but less so with the guage the important point is the empty level !! Sorry the Rheostat does not work on heat it is resistive and fairly linear there is little to no current drawn as this would not be desirable in a fuel tank! |
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Post by Warwick on May 30, 2011 10:21:33 GMT
I think he means the gauge itself John, not the reostat in the tank. That is to say, the gauge isn't a normal moving coil or moving magnet meter but a bi-metallic thermal device.
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Post by Deleted on May 30, 2011 10:45:49 GMT
As above ; thats why when you fill up, the needle takes time to get to full scale and not instantly jump to full
Many moons ago I used to work in a standard calibration room for my sins , so luckily the electrics holds no fear for me - good job as my car needs a fair bit of sorting in this area !
I did a quick volts check around my car and there are high resistances everywhere !! lots of poor connections and corroded connections over the years
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Post by mcgill on May 30, 2011 10:46:50 GMT
im after getting my gauge to move,i know i did it once as i wrote off the sender as usless.................
Also as a side note,the ohms at which the gauge works,can this be boosted or altered,basically id like to connect it up to my 0 to 90 ohm lpg sender???
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Post by johnwp5bcoupe on May 30, 2011 14:13:02 GMT
im after getting my gauge to move,i know i did it once as i wrote off the sender as usless................. Also as a side note,the ohms at which the gauge works,can this be boosted or altered,basically id like to connect it up to my 0 to 90 ohm lpg sender??? Right lets see if we can sort this out  :- The Guage has a Bi-Metallic strip which moves the Needle on a P5b. Tank Full Rheostat = 30 Ohms Tank Half Full = 120 Ohms Tank Empty = 257 Ohms So near enough Linear I cant see an easy way of converting so you can use it on LPG other than playing around with the supply voltage to the Meter/Rheostat it should work with a bit of trial and error Sorry luxurybarge we were on tank Rheostats then we went to the Gauge |
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Post by Deleted on May 30, 2011 22:44:12 GMT
im after getting my gauge to move,i know i did it once as i wrote off the sender as usless................. Also as a side note,the ohms at which the gauge works,can this be boosted or altered,basically id like to connect it up to my 0 to 90 ohm lpg sender??? May be possible to add a thermistor with 30 ohm starting resistance but any lpg guage is not going to be that accurate |
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