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Davo

Fuel Gauge Troubles

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Just googled sierra fuel sender and they look pretty similar, the wire in the middle should be the sender wire and the other ones maybe earth, if you can remove it and move the float up and down then resistance will change.

 

Measure between earth and the centre connector without wire connected otherwise you will be measuring gauge as well, I made that mistake!!

 

If you can't remove it then measure what it is now and then put fuel in and see if it changes.

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If the tank/gauge sender is not leaking leave well alone !! I found it a right pig to get a seal on the RH tank, so on 3rd attempt (& success ) I concluded it was as good as I would get although the gauge reads empty when still with enough fuel for 50 miles max.

A jerry can of fuel will allow you to measure actual contents against gauge reading.

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Looking now in daylight, tested the wire that goes to the male connector and when there is ignition, there is 8v on that wire. Not sure what the other two male connectors would be for though.

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Ive had a look at what I think is the right diagram in Haynes, but I can see two different fuel sender objects.

post-13976-0-76969400-1533731084_thumb.jpeg

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Hi Davo

You need to measure resistance not voltage, if you google how to test fuel sender it will show you what to do.

 

Whats the tank from?

Edited by geordie40

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Thank you. I’ll have a read.

 

As it happens, from fiddling the wire popped off and earthed itself on some metal; shortly after that the gauge went to the top. So at least I know now that the gauge works.

 

The tank looks like it’s a shiny rectangular one so I’m assuming it was custom for the kit car.

 

The sender part though looks like it is part of a larger unit that encompasses the fuel line. The larger unit is secured by four nuts. I don’t think the plastic sender part comes out on it’s own.

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Hi Davo

 

This is my sender unit but mine has the fuel pump all in one (its from a fiesta/escort), the wires on mine are

 

Red 12v for pump

Black = earth

Brown = sender

 

If I disconnect the green wire from the brown and put my meter across the brown and black (meter set to Ohms) then I get a reading of approx 20 ohms empty and 150 ohms full.

 

The sender is the whole thing on yours I think so undoing the 4 bolts will remove it all.

 

post-14299-0-92618300-1533753651_thumb.jpg

 

 

Yours will probably look something like this

 

 

post-14299-0-81649500-1533754250_thumb.jpg

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Mine does look very similar to that.

 

Sadly I suddenly I have bigger problems so I might have to pause this.... water pouring from below the crank case pulley. :(

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The sender had other connections that ford used to give MPG and low fuel warning. (MPG was a joke).

There was a separate earth spade terminal the should be connected for the gauge to work correctly.

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So theres two possibilities here maybe.

1 I actually have an electric fuel pump built into the tank and it should be powered by 12v using one of the other spades on the block

 

2 the additional spade is for flow or something

 

Either way the unit needs an earth which for good reason its not going to get off the fuel tank.

 

In short, I need to Earth it on one of the spades. ?

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The tank should have a separate earth connection entirely separate from any earth necessary for operating senders pumps. As in mains electrical works it needs bonding to the main earth/neutral.

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Hi Dave,

Yours looks like an original Sierra sender. I’ve just changed mine as it was leaking fuel from the uptake pipe braze. However, I agree with The District Sec - if you can , leave it well alone. It is very hard to reseal. I managed eventually by using a manufactured steel ring over all x4 bolts to apply a more even pressure to the gasket.

Try recalibrating your gauge with a Spyider module ? You wouldn’t need to remove the sender.

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Chance we may meet this Sunday, Bob?

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Hey thanks for the tips. I gVe into temptation in the end and removed it to see what was going on. I didnt really learn anything more other than it looks like three separate circuits inside corresponding to each of the pins. However, after putting it all back together it now works! Im not convinced the tank is sealed properly but at least I have a working gauge that looks about right.

 

Jonny, I live in redhill near parley. Would be nice to meet someone local to chat things over. Im a bit of a newbie.

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