Fuel tank's

[Rich.f]

I am sure there has been a post on this subject before but can't find it!. I have tried to run one of the tanks totaly empty, when the fuel gauge is showing empty the car keeps running, so switch to the other tank and find it half empty/full. I have tried using them the other way but get the same result.
How??????

The other quiery, is 11 - 12mpg good, bad or just expected.

Rich

[peterpsg]

Have you got a balance pipe?

And is the fuel sensor mounted on only one tank?

Make sure you have a good fuel filter installed before you try to empty out a tank...

I've had bottom-of-the-tank-diry clog jets on some of my early cars in my student days when I had to get by on the smell of an oily rag for gas...

[craig-ultima]

My gauge doesn't read correctly. Tank is about 1/3 full on empty. I haven't filled it to the top, but the gauge doesn't look like its rising fast enough to measure full.

I've just finished the build, so this is on my debug list. Curious to hear that I'm not alone in this. I have two tanks, two senders, balance hose, standard Ultima gauges.

[steve_D]

Rich.f said:

I am sure there has been a post on this subject before but can't find it!. I have tried to run one of the tanks totaly empty, when the fuel gauge is showing empty the car keeps running, so switch to the other tank and find it half empty/full. I have tried using them the other way but get the same result. How?????? The other quiery, is 11 - 12mpg good, bad or just expected. Rich

I've made 18.5 to the gallon on a long fast run. 407ci (6.7L).
The tanks will level out if you have a balance pipe linking the two. One can be run right down at the bottom or part way down the tanks.

Steve

[mclark]

Craig,

Mine measures about 1/4 tank when empty, as I found out when I took the car to the Rolling Road guy last week.

How cool did I look when it wouldn't start first go ;-)

Been told this is normal for the VDO gauges/sender.

BTW how many litres do each tank hold?

Michael

>> Edited by mclark on Tuesday 30th August 21:51

[Rich.f]

When you say "balance pipe" I asume you mean the pipe at the top connecting both tanks, I thought this was a overflow pipe and therefor assumed that this could not pick up the fuel once below the level of the fitting! Yes I do have two fuel senders and pumps as recomended, each pump has a one way valve after it then leading into a "T", from this into a filter then through a regulator finaly the Holley carb's. I will lookforward to a long run and hope for the 15+, didn't realise there were so many filling stations, funny how you notice these things! mind you WOW is it quick and worth every penny.

Rich.F

[Rich.f]

38 Liters in each tank, Think that was it.

Rich.

[pb3]

Hi Rich,

Uhm, Ultima fuel gauges (ask tuxman what he thinks). I have heard a number of tails about the accuracy of the gauge display. I did something different, my own electronics so calibrated both senders litre by litre (great fun). What I found is that the senders are not amazingly accurate (ie the resistance changes at will) but also that on one side it took about 5 litres before anything registered and four on the otherside. The balance pipe "should" be at the top but you will find that fuel is leached from the other tank until the fuel is below the balance pipe (obvious really, but always looks odd on an accurate gauge). I can put in say 60 litres on "empty" tanks and my fuel total display would show something like 61 litres. I am pleased I did what I did, getting 14 to 18 mpg having a gauge you can trust gives some piece of mind.

[davefiddes]

The VDO gauges have a little trim pot that you can adjust to set the zero position:



If I ever get any time to work on my car I intend to feed the sender through my ECU to linearise it. Of course it's only as good as the sender but it's not hard to improve on a stock VDO gauge even when it's adjusted properly.

Dave

[GTRene]

Why don't we talk here in Liters per mile or km, because you all talk about gallons per mile, but in the USA 1 gallon =3,78ltr and GB 1 gallon = 4.54ltr, that explains the different outcoms about miles per gallon for the same cars?! and there are a lot USA people also on PH, and why is a AM gallon different as a GB gallon???
Luckely here in Holland we use the metric? system so you know what we talk about, here it is, litre per 100km.
Here in Holland we pay 1,48euro per litre! the highest anywhere...we better move to Venezuela, I've heard the only pay 0,03eurocent per litre! the lowest in the world and America about 0,60? per litre eurocent I guess, what do you pay for 1 litre RON 98 in GB? in euro's..

greetzzzz
René

>> Edited by GTRene on Wednesday 31st August 09:58

[Crazy of Cookham]

Interesting but difficult to determine when the tank is empty, short of running out. I have driven upto 10 miles with needle resting on the empty pin. Really not sure what is left in tank. When you fill some always transfers to empty tank so cannot calibrate this way.

[andygtt]

GTRene said:

Here in Holland we pay 1,48euro per litre! the highest anywhere...we better move to Venezuela, I've heard the only pay 0,03eurocent per litre! the lowest in the world and America about 0,60? per litre eurocent I guess, what do you pay for 1 litre RON 98 in GB? in euro's.. greetzzzz René

it just hit £1 per litre which is around 1,4ish euro per litre here in the UK!

>> Edited by andygtt on Wednesday 31st August 15:29

[GTRene]

andygtt said:

it just hit £1 per litre which is around 1,4ish euro per litre here in the UK! >> Edited by andygtt on Wednesday 31st August 15:29

1 GBP is about 1.48euro's so you pay about the same as we do! also too much...thanks for the info.

does anyone know why a USA 1 gallon is 3,78litre
and a GB 1 gallon is 4,54litre?

I thought a gallon is a gallon...hmmm not so

[pb3]

The calibrated measuring jug got dented on the way other a few hundred years ago

[gtr4me]

GTRene said:

does anyone know why a USA 1 gallon is 3,78litre and a GB 1 gallon is 4,54litre? I thought a gallon is a gallon...hmmm not so

Well one of them is talking about a US Gallon, the other person is talking about an Imperial Gallon.

1 US Gallon = 3.7854 litre
1 Imperial Gallon = 4.5461 litre

>> Edited by gtr4me on Wednesday 31st August 16:41

[menostig]

On my Sports if I refuel one tank, and keep the other empty, after 30mins of spirited driving, I find both tanks nearly balanced again. But the balance pipe is up the top of the tank, so eithere there is fuel slosh under spirited driving despite the foam filling OR I've noticed that when car is in garage for a while the tanks tend to level out and I put this down to the one-way valves in my 6yr old Facets being no longer one-way.

Despite this, under straight line conditions I've driven past empty on one tank for about 10-15 miles and the car stuttered so I switched tanks and the rpm fell for a few seconds before recovering.

All this discovered while absently wondering what fuel consumption is on 750cfm Holley'd 5.7L ZZ4 (360bhp). Only reliable measures so far - average 15mpg over 10 fills, and 27mpg (brimmed tanks at start/end) for a disciplined 90mph cruise over 160 miles. This gets boring and I'd much rather scare myself and be rewarded with 10mpg.

regards
Roger

[GTRene]

I know a Ultima have 2 tanks and 2 filling points, but why can't they make a low pipe between those tanks so they work more together? so you only need to fill one and that automatic fil up the other? that way your car and thanks are always in balance, or is that not possible? I don't have an Ultima yet so I don't know.
and you have to switch from one tank to the other? hmm
so it not works like a say "normal' sportscar? like my Z3 M coupe?...

[steve_D]

GTRene said:

I know a Ultima have 2 tanks and 2 filling points, but why can't they make a low pipe between those tanks so they work more together? so you only need to fill one and that automatic fil up the other? that way your car and thanks are always in balance, or is that not possible? I don't have an Ultima yet so I don't know. and you have to switch from one tank to the other? hmm so it not works like a say "normal' sportscar? like my Z3 M coupe?...

The low point on each tank is connected on my car so I only pump from one tank. The pipe is not large so filling from one tank would take a long time.

Steve

[mkoch1]

I have a -10 line on the bottom of the tanks but still end up filling from both side. My set up only pulls fuel + return fuel to one tank. The balance pipe effectively makes it like having one large tank. Only down side is if I run out of gas I don’t have a reserve tank to switch over 2.

Mark

[GTRene]

mkoch1 said:

I have a -10 line on the bottom of the tanks but still end up filling from both side. My set up only pulls fuel + return fuel to one tank. The balance pipe effectively makes it like having one large tank. Only down side is if I run out of gas I don’t have a reserve tank to switch over 2. Mark

So its possible to have a low sitting connection at the tanks, only the balance pipe is a bit small... you don't need then to switch over annymore but as you mentioned that way no reserve...but does the fuel gauge(1 or2?) have a reserve orange warning light? or do you have to guess how many litre's you have left...
thats a bit like a gamble when doing 10 or 12 miles the gallon thats about 1 litre every 3,6 or 4,3 km..
now where is that tankstation...