More petrol tank problems

[nickacb]

Hello everyone

It's been a real ordeal to get my tank to work again. First I decided to trash my old one (mk1-mini) beacause it was complety full with rust inside, so I took it to a "friend" who said he could make a repro in inox. Needless to say the artisanal repro never fitted.

I decided to salvage the original one. It was cleaned form the inside but now I got two porblems:

First, the inner tube was complety blocked. Not a single fuel drop came out of the tank. By use of compress air and all sorts of DIY technics I managed to unblocked it, by which I mean If you blow from the outside take now you can feel the air flowing to the inside. My question is if that would be enough? How could I tell if the inner tube is "unblocked enough" to let the gas flow normally.

The other thing is that the cable that sends the signal to the dial to know if the tank is full or emty is disconnect underneath the boot. I mean, this cable has two ends, one with two cables which should be connected to the tank but the other end is disconnected wich I discover when I connected the gas hose form the tank to the tube. Could someone please tell how should I connect this end of the cable please.

Thanx

[1071 S]

Hi Nick,

You do realise that the tube that allows fuel to flow to the carb has a small filter on the end inside the tank?? Usually when people clean the rust out they use a chemical agent that can completely block this filter.

The easiest way (I'm told - not had to do it myself) is to stuff a stiff bit of wire down the fuel feed pipe and and keep pushing (shoving the wire until you can feel the end pass freely into the tank. This will dislodge (or destroy) the small filter ... but is no big deal as you can fit an external filter in the line that goes to the carb.

As for the fuel level wires... Is the fuel gauge sender attached to the tank by a number of small screws around the edge of the sender (Type A)..or large ring that slots into notches in the edge of the hole in the tank (Type B)??

If A... then you will have a green wire with brown trace that goes up inside the left hand side of the roof and attaches to the fuel gauge and a black (earth) wire that goes back and shares an earth with the number plate light (although being an earth it doesn't really care where its attached to the body). This what you should have for a Mk I .... but a lot of strange things can happen in 50 years

I B..then the green/brown wire also goes to the fuel gauge but there will be an addition light green wire that goes to the "I" terminal of the voltage stabiliser which is attached to the back of the speedo. The black wire is the same as A.

Its possible you could have a Type A sender and a Type B gauge. If so, they don't play together (A is 12V and B is 10V). You can tell which gauge you you have by how it acts when powered up. The A type needle will "flick" to the correct (or maybe incorrect) reading; the B type is more sluggish and sort of creeps across the dial until it reaches the correct reading....

Cheers, Ian

[nickacb]

Thanx a lot Ian

As for the pipe I guess I managed to unblocked it, and yes the guy who cleaned it destruyed the filter

As for the connection I guess I have type A

But not really sure i understood you right

See, the floor of the boot has two holes. One for the gas hose so it can be attached to the tube underneath the car

The other hole is for the gauge cable wich is loose underneath the car but I can’t any place yo Connect the cable underneath the car

Hope you can clarify a little bit more please

[Maddog]

Hi Nickab, the wires that go to the fuel sender unit on your fuel tank are part of the main rear wiring loom that come into the boot from the left C pillar. The wires route behind the tank to the sender. They don't got through a hole in the floor.

You might be mistaking the power and earth wires that do go through the floor to the original SU electric fuel pump. Both sets of wires have small eyelet connectors so it is easy to do - I made the same mistake when rewiring my car. It is obvious though when you look at the loom and the length of the two sets of wires which ones go to the tank and which ones are long enough to go through the floor to the fuel pump.

Hope this suggestion helps.
Cheers

[Peter Laidler]

Nick and anyone else having a blocked or partially blocked fuel outlet pipe, here's an easy fix. Get a 6" length of that bendy coiled net curtain wire stuff that your mum used to hang the net curtains. (Strip the nylon coated cover off it if it is covered.....) and stretch the last inch or so to open up the coils.

Put the other end into a drill chuck and insert the open coiled end into the open end of the jammed pipe. Turn on the drill SLOWLY and the wire with rotate its way into the tank unblocking all the shi..... er......, gunge as it does so.

A 6 foot length of this cheap curtain wire is always a good thing to have in a garage for pulling wires through or, as I did the other day, pulling a length of cloth around the back of my petrol tanks

[nickacb]

Thanx for all the answers, all have been very helpful

[AndyPen]

Just a quick note to add that the breather pipe for the tank also goes through the floor