fuel sender

Information courtesy of Chris Manley "WildfireS3" of the Pistonheads forum

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Before removing the sender unit check that it is not an electrical fault elsewhere on the car. This can be done by shorting out the gauge. Turn on the ignition and connect the two spade terminals from the fuel sender unit together using a fused meter between the connection. The gauge should read full. Also check the earth to the tank which is located on the chassis near the nearside top left hand corner of the fuel tank. Some cars have earths on both sides so also check the offside top right above the tank. This should be cleaned off, checked with a multi meter, then covered in Duct Tape.

Also check the main earth on the chassis near the passenger footwell. If all of the above are in working order then it is likely that the sender unit has gone. The sender unit is specific TVR part, which is only available from TVR. The lock ring and seal, however, are common to many cars including classic minis.

Tools Needed

1. Flat Bladed screwdriver, with tape over the end, or some sort of similar tool, plastic preferably.

2. Small hammer

3. Gaffer/Duct/Elephant tape

4. Wheel Brace

5. Jack and axle stands

Parts required.

TVR Fuel Sender Unit,lock ring and a rubber seal

Process Ensure that there are no naked flames, or objects that could cause a spark before attempting anything. Remove - ve then the +ve cable from Battery to ensure no accidents. Run the car as low as possible or drain the tank. I have found that if the fuel level is about a quarter full it is sufficient to remove the sender unit without fuel spilling out, but it is still dangerous to do so. Jack the car up under the left hand wheel and place securely on axel stands. Then remove the wheel. Jacking under the left wheel cause the fuel to flow to the other end of the take away from the sender unit hole You will see the fuel sender unit about half way up the side of the tank, it will have two spade connectors on it which consists of two wires, one green and one black. Note which way these are attached then remove them and push them up out of the way Removal of the sender unit is very simple, take your screwdriver with the end taped over (to avoid a spark) or better still wood or plastic drift and but it against one of the tabs that extend from the lock ring. Using the hammer gently tap the lock ring tab so that the lock ring spins anti clockwise. Be careful not to damage the tabs if you plan to re use the lock ring. But for the sake of £2 or so it is advisable to buy a new lock ring. Once the lock ring has unscrewed remove it the gently pull out the sender unit, followed by the rubber seal.

	To check if your sender unit is damaged, first check the track on the main body. This is essentially a variable resistor, but wears out easily. If the track appears intact check that the float at the end does not have a leak in it. 9/10 cases it is the track that is gone.

	To replace, first put the seal back into the housing, then carefully insert the sender unit back through the hole in the tank. The Unit has a notch at the bottom (6 o'clock position) which is designed to located on the fuel tank, if this does not locate ten the sender unit bottom will not fit in.

	Once you have located the unit put the lock ring over the top. Then making sure it is as central as possible turn it clockwise. There are 3 ramped "locks" on the ring which are designed to hold the unit in place. Once you have done it up tightly, give it a few taps with you drift to push it round more. Be careful not to break off the tabs, also check to see that all three ramps are securely tightening, I found that often if the ring was not central, two would tighten and one would pop out as I tightened it.

	You may find that some kind person has damaged the tank when previously replacing this item. In this case you have to do the best you can to bend the lip on the tank back into it's shape without weakening it.

	The lock ring does not have to go round to the highest part of the ramp. Once back on replace the spades and wheel. Wipe around the sender unit clean and dry and drive up the road. Then check for leaks. If it does not leak, cover the Spades in Duct tape.