alan
Rover Newbie
Posts: 5
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Post by alan on Aug 17, 2008 23:01:19 GMT
Hi All, our fuel gauge wont read over 1/4, even when tank is full, how can i test if the sender is working ok without taking it out of the tank?
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Post by johnwp5bcoupe on Aug 18, 2008 6:16:53 GMT
Hi All, our fuel gauge wont read over 1/4, even when tank is full, how can i test if the sender is working ok without taking it out of the tank? If you remove the cover hiding the tank, take the spade connectors off the sender (one being earth) and short them together the gauge should read full if not it's a case of removing it try cleaning the sender first if no luck try David Green
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Post by Warwick on Aug 18, 2008 8:22:32 GMT
And remember to disconnect the battery before removing the sender and thus opening up the tank.
A fuel tank sender is a simple reostat with exposed resistance windings and contact wiper.
If there is a fault, it is very easy for it to make a spark at the point where the contact moves across the wire windings.
Even a tiny spark is capable of igniting an explosive mixture of petrol vapour and air.
The only reason it doesn't do this when it is installed inside the tank is because there isn't enough air - it's mostly petrol vapour.
The explosive range for petrol is 1.4% to 7.6%. 1.4% is the Lower Explosive Limit (LEL) and 7.6% is the Upper Explosive Limit (UEL).
This means that a mixture of between 1.4% and 7.6% petrol vapour in air WILL explode if a source of ignition is present.
Outside of this range the mixture is either too lean or too rich.
The vapour space inside a closed petrol tank is very rich. (Not much air - Mostly vapour)
Open up the sender gasket and you let in some air right at the point where the ignition source (wiper contact) is located.
And also remember that an empty fuel tank is NOT EMPTY as long as any trace of vapour remains.
This is why people around the world regularly kill themselves by attempting to weld or cut an "empty" fuel tank or drum.
Don't be the next one.
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Post by Phil Nottingham on Aug 18, 2008 9:32:34 GMT
Wise words!
Also make sure the gasket is not damaged when refitting and all the screws are tight
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Post by johnwp5bcoupe on Aug 18, 2008 10:02:32 GMT
Not enough current drawn to produce a spark other wise as the rheostat moves it would cause a hazard ;D But wise words any way Warwick It may not be an easy job to remove the locking ring break the paint seal as best you can then try taping it with a blunt drift of some sort not a sharp screwdriver.
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Deleted
Deleted Member
Posts: 0
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Post by Deleted on Aug 18, 2008 10:57:12 GMT
JRW does new senders. Suggest ordering one before you open the tank. They usually sieze in the ally die casting. Its not easy to unscrew the locking ring without a special tool. It does not have a thread but sloping slots that engage with dimples in the tank opening.
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Post by Phil Nottingham on Aug 18, 2008 11:32:57 GMT
Early tanks had screw locators but the locking ring is only light mild steel soyou really need to make a tool with 3 x 120ยบ lugs on it to avoid bending it - hopefully you will not need it! It may be a wiring fault
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Post by Warwick on Aug 19, 2008 0:34:58 GMT
Not enough current drawn to produce a spark other wise as the rheostat moves it would cause a hazard ;D Thanks John. I've edited my post to show that a fault is necessary.
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