The basic reason my petrol gauge doesn't work is because the float has dropped off at the sender end. Could someone tell me how it is supposed to fit to the sender, I can think of several ways but keen to know the correct method.

I've never heard of a float detaching itself from the sender rod. I presume you have the correct sender unit?

Assuming you have, the metal float is silver soldered across the end to the sender rod. There should be evidence as to where it was originally attached on both items. The float must of course be in line with the top surface of the sender. Check that the float is still airtight before you re-attach it.

Sorry I didn't make it clear - the rod is disconnected or broken from the spindle end. The spindle just has a hole through which I assume the rod goes, but how is it fixed?

The rod is an interference fit in the hole Nick.

Thanks Ruairidh - there is absolutely no fear of interference here! I think solder might be the solution. Is the length of the rod vital? my little brain is trying to work that one out! I am thinking that if this bit of car is as bodged as the rest was then maybe the rod was fixed by some other obscure method and therefore is not an original length.

As said above,the wire holding the float is an interference fit through the spindle hole. Whether it can be soldered I do not know.
Now for the tricky bit to explain:-

a) The distance from the centre of the spindle to the centre of the float, in a straight line, would be 142mm.

b) The actual length of the wire fitted between the centre of the spindle and the centre point of the side of the float is 155mm. The wire is cranked gently to the right and then left halfway along to achieve distance a) above. When done correctly, the float lies centrally in front of the actual sender unit. As I added previously, it must also be parallel with the top of the sender unit.

Hope that helps.

Thank you, yes it helps but I have 153mm from centre of float to centre of spindle. Looking at the float there has been a lot of soldering in the past - can you confirm that the float should be at right angles to the wire, as in a paint roller, or longways?

L shaped.

I'd use the measurements as a guide but then make sure that when the connected gauge reads less than a 1/4 tank or 1 gallon the float is just sitting 1/2" above the bottom of the tank. Measure down into the tank to the bottom and set that distance between the sender flange and bottom of the float. It's hard to get this and the 'full' readings both reading correctly but of course it's empty that's the more vital information? You can bend the wand a little to get the float position at the right height at the two kinks descibed above.

Dave

Thank you for that advice. I now have everything re assembled and fitted and not working! So, I see there is and article on Cornwalls website on checking through the system so now have that in front of me on the bench.

Just to update this thread - I have the system up and running but the reading on the gauge is variable and no where near correct and won't record anything over 1/4 full, so I have come to the conclusion I probably need a new sender. I suspect serviceable ones are tricky to find but I remember reading somewhere that a mini one could be adapted.