10 replies to this topic

[yorkshirechris]

The mini concerned is a 1980 Mini GT with the larger fuel tank & 2 connections on the sender unit.

My Mini, DOminic has decided he doesn't want to tell me how much fuel is in the car anymore...

My ever so simple question is

How do you remove the fuel sender unit?

And

If the tank is full of fuel am I likely going to get doused in fuel?

Thankyou in advance

[GraemeC]

Tap the locking ring anticlockwise until it comes free then simply lift the sender out.
If the fuel level is above the sender then yes, it will fill the spare wheel well!! Look through the filler neck with a torch (flashlight for Doug ) and see where the level sits in relation to the sender.

Edited by GraemeC, 01 July 2009 - 03:42 PM.

[yorkshirechris]

Tap the locking ring anticlockwise until it comes free then simply lift the sender out.
If the fuel level is above the sender then yes, it will fill the spare wheel well!! Look through the filler neck with a torch (flashlight for Doug ) and see where the level sits in relation to the sender.

Ah the level will be a tad higher than the sender because I filled the tank to the brim last night I was too scared of running out of fuel...

I'll run it down and then have a go. I wonder how many unneccesary miles I can do to annoy the green party

[dklawson]

(flashlight for Doug ) and see where the level sits in relation to the sender.

Thank you Graeme. I'm sitting down comfortably.

Before you remove the sending unit you should perform a few quick and simple tests and answer a question.

First, does the temperature gauge still work properly? If the temperature gauge is acting up, the problem is likely to be the voltage stabilizer or power to it.

The simple sending unit test involves a length of jumper wire (some will say paperclip, I don't, and I'll explain why in a moment). In the boot, connect a short length of wire between the sending unit's green/black wire and the earth terminal on the battery. Switch on the ignition and watch the fuel gauge. If the gauge does NOT go to "Full", there is a problem "ahead of" the sending unit.

If in the test above the fuel gauge goes to full, the gauge and voltage stabilizer are working. Your next test is to remove the jumper wire from the battery earth terminal and connect the free end of the wire to the BLACK wire connected to the fuel sending unit. If the gauge does NOT go to full, the problem is in the earth (black) wire and/or its earth connection. If the gauge DOES go to full, the problem is inside the sending unit and you are justified in removing and replacing it.

As mentioned above, a lot of people just perform a quick test with a paper clip between the green/black and black wires on the sending unit. That's a valid test as long as the black wire on the sending unit has a good earth connection and isn't broken. If there is any problem with the black wire, you will get a test result that looks like the sending unit is bad... when it may not be. Using a jumper wire to the battery earth terminal first prevents this possible misdiagnosis.

[yorkshirechris]

I think I understand what you mean.

I removed both wires from the sender unit & bridge them, turned on the ignition and the fuel gauge went straight up to full. I thought this would be sufficient to prove it onto the sender unit? Because if the black earth wire has a bad connection somewhere, surely the connection I bridged simply would not be made, and the gauge wouldn't shoot up to full?

I think it might be something to do with the fact a week or two ago I accidentally dropped the inner cardboard disc from cap off my bottle of Redex into the fuel tank, could this have got caught up in the sender unit/float?

Edited by yorkshirechris, 02 July 2009 - 05:52 PM.

[dklawson]

Yes, your test is OK. Bridging the two wires confirmed the sensor is bad.

My point with the extra step using the jumper wire was to stress that IF you had a bad earth wire, the bridging test will give the same indication as a bad (open) sending unit. If the float were somehow wedged in the bottom of the tank by the bottle gasket you would still see the gauge needle come off of the extreme left (beyond empty) part of the gauge by some small amount.

Sorry you dropped the bottle seal into the tank, however, it's very unlikely to have caused your problem. There are two common failures on the bayonet mount sending units. The first is a failure of the sending unit's internal resistance wire. The second is that some senders have a brass buss strip that is on the "outside" of the sender but inside the tank. These can fatigue and break into two parts which no longer conduct electricity. The broken buss strip is easily soldered back together (with a heavy soldering iron). The internal wires being broken are best handled with a new sending unit.

[yorkshirechris]

Aye the needle is right down to the extreme left, below empty.

Cheers for your help. Looks like I'll have to wait a while to run the fuel level down because I hardly use the car

[orac69]

Hi,

Can anyone advise how to get the blasted fule sender unit back into the tank..

I can get the unit / float back in by turning round / angling it back etc. but the metal round sealing plate doesnt seem to want to match up to the lugs - it seems awfully tight and wont push back in firmaly when using fingers - is it just a case of brute force to get it back into place?

There are only the 2 little wire connection lugs to hold on to - and I dont want to snap them off in the jaws of pliers etc..

Help !

[dklawson]

I have seen new bayonet rings that are a bit large and they can be a bit hard to fit to the opening in the tank.

I suggest removing the sending unit and "dry fitting" the bayonet ring first. Make sure it will enter the opening on the side of the tank. Remember to look for and index it around to the three possible positions where it will line up with the "nubs" on the tank entrance. If necessary, you can file away a bit of material on the perimeter of the ring as needed... but try all three possible positions first.

Once you know the bayonet ring will fit, put a new gasket (and only one gasket) in the tank opening followed by the sending unit. The sending unit should have some squarish weldments on the back side that prevent it from going in any way but the correct way. These also prevent the sending unit from rotating. You should NOT have to hold or turn the sender with the electrical terminals when you fit the bayonet ring. After the gasket and sender are installed, put the bayonet ring in and turn it (using its ears) until it locks the sender in place. Then use a flat blade screwdriver and small hammer to tap the bayonet rings around a bit more to compress the gasket.

Make sure you have not perhaps left an old gasket stuck to the entrance of the tank and remember that the gasket goes between the tank and sender, not the sender and the bayonet ring.

[orac69]

Thanks, but it doesnt seem to be the bayonet ring / gasket which is the issue.

No matter what I try I simply cant seem to get the sender unit / squarish weldments to line up, for the plate to actual fit flush into the hole..

All parts (inc the gasket / ring) appear to be identical in size / shape to the old corroded one I took out.

I'll have another fiddle this evening... Just thought there may be a knack to getting it in.

[Minisport7]

Also having this problem. Any solutions?