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stephenh

XI Fuel tank capacity

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Hi, Jon,

To design and install a tank between the bulkhead and the axle would be quite an undertaking (though would not impact on the feel of the car as much as filling and draining a six or seven gallon tank right at the back of the car).  The mid-mounted tank would also require re-siting the battery and amending the routing of the brake pipe to the axle.  Probably two pickups and two pumps to collect the fuel on both sides of the propshaft / diff as I would think that the tank would end up being a "saddle" tank type and there wouldn't be room for a sufficiently large link pipe to run between the two wells.

I am a person that covers many miles, sometimes with work, but more often going to rallies and taking part in scenic tours for pleasure.  When my late parents were ailing up in south Scotland, I regularly took a 650 mile round trip - on four occasions doing this in a day!  I will quite often do between 350 and 400 miles in my old cars taking part in scenic tours.  When going up and down the M6, I was quite happy to be in a VW Passat that has a 700 mile range but have to say that I am not at all offended to pause in the Eleven when the little tank needs topping up (around 100 miles) and having a wander about.  A function, I think of the rather cramped footwell.  With French service stations and villages quite often being so pleasant, a couple of stops there ought to add to your enjoyment of your journey to Le Mans!

Hi, Stephen,

Something must be awry with your sender or its installation to give you the "all or nothing" reading.  A calibrated garden cane to dip the tank may be the way forward for the moment.  It should stow nicely alongside the passenger seat!

Simon

 

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Well I think I've found the problem; I've got a negligible resistance across the terminals on the sender. regardless of whether the float is up or down, so no wonder the gauge reads over full all the time!

Whilst on the subject of wiring to/from the fuel tank, why do i need  separate earth from the tank? isn't the tank earthed through the earth wire which goes to the sender unit on the Westfield wiring loom?

Anyway, looks like I need a new sender. I'll check first to make sure that I haven't inadvertently got a short between the live wire to the sender, and the body of the tank.  

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My understanding is that the extra earth is there for one of those unlikely, but "what if" scenarios.the gauge earth is often quite a light weight "instrument" level earth, Whereas the additional chassis earths are intended to cope with a significant belt from a static discharge.

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OK, Dave, thanks. Just that with my fuel gauge problem I was thinking through the wiring at and around the fuel tank thoroughly to try and puzzle out what is going on, so I'll leave it with 2 earths.

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I've done an unbelievably stupid thing when trying to test my fuel gauge. So stupid that I hardly dare mention it on here, but they say confession is good for the soul, so here goes.

The chap I'm in contact with at Spyda, in fact I think he is the chap who designed the gauge wizard, is being very helpful, and wanted me to bridge the input lead which goes to the gauge to earth, and check that the needle swings all the way from one end of the dial to the other. I don't know why, but without thinking I bridged from the input wire to the live feed to the gauge instead of the earth. Instantly there was a soft "pop" sound, just like when a car fuse blows, and it has cooked the wizard. :down::cry:

Anyway, I have told the chap at Spyda what I've done, and he just confirmed that it will have cooked the wizard, but if I post it back to him he'll sort it out and make it better. A great service to be acknowledged.

Oh, and I was wrong about the sender unit, I took it off and took it to a friend who has a more sensitive multi meter than me (ie the resistance function works!) and the sender is working, it is just that the resistance is much lower than other models. The range seems to be progressive, from about 3 ohms to about 60 or 70 omhs. So although it may not be completely compatible with the gauge the Wizard should be able to match the one to the other. 

So now I'm wondering if I have connected the wiring at the back of the gauge wrongly. How do I work out which of the terminals on the back of the gauge is for the switched live feed, and which is for the sender input? Or doesn't it make any difference?

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Hi, Stephen,

I've attached a couple of images - one shows the back of the fuel gauge (lower of the two gauges with the red and green wires) but they don't make clear what I connected to the existing wiring, I am afraid.

I would have thought that orientation was important.

IMG_1215.thumb.JPG.092558c6df4c5cc97dfa72fe5d5fcb6f.JPG

IMG_1214.thumb.JPG.6033a4f01ff91bbf206b097a4a90baf0.JPG

Good Luck - with the investigations you have made to date, it should work.

Simon

 

 

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I can't be sure from Simon's photos, because your wiring seems to be a different colour coding to the Westfield loom which I used. However, I've found pictures of the back of the gauge having googled "how to test a Midget fuel gauge" and I think I had my 2 input wires the wrong way round, which might explain why the needle went in the wrong direction as the tank went from full towards empty before I fitted the gauge wizard, so I've reversed them.

In the meantime, I've sent my wizard back to Chris Horne, who designed and produces them, and he has replaced it for a very modest sum, and turned it round in 4 days including post time each way! Incredible service, which certainly encourages me that if you have problems with an old style electromechanical gauge not working accurately then don't have any concerns about getting one of these devices.

Now to fit it and get it set up!

 

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I believe I did have my gauge wired the wrong way round. Now I've changed it, and fitted the replacement gauge wizard, it works after a fashion. However when I did a 93 mile round trip a few days ago the gauge was showing full or nearly full until the tank had dropped to about half full or thereabouts, and when we got home it was down to about 2/3rds. full according to the gauge, but a dipstick check showed that the level in the tank was more like 1/4 or 1/3rd. Not really possible to say exactly from a dipstick check, because of the shape of the tank. So now I'll have another go at programming the wizard to the sender and the gauge, and hopefully we'll be getting there.

At least it shows that the gauge wizard works, if it is correctly programmed.:t-up:

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