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        General >> Give/Need advice to/from others >> Fuel sender gives wrong value
        
(Message started by: tlundkvi on May 5^th, 2009, 9:07am)

Title: Fuel sender gives wrong value
Post by tlundkvi on May 5^th, 2009, 9:07am

Had my tank replaced yesterday to a new "replica" (exact shape etc.). But what I notice is as I filled it to 70 litres, is the tank sender shows between 2/3 and 5/6ths full and board computer "km till refuel" accordingly. Service guys swear the sender unit was treated with utmost care.

Is this common, or does the scorp have some strange reactions when fuel levels change abnormally? When I drained the tank quite a lot on sunday, it took a 10km round until the dash indicator showed correct levels. Can there be something wrong with the alignment (if it is tilted somewhat, it looks OK to me)

Or have they just bent the float lever a bit and don't admit it?

It was btw a rusty thing, far worse than I thought, and it didn't (luckily) spread to the trunk. Will post a picture when I get it from my mobile phone.

Title: Re: Fuel sender gives wrong value
Post by scorpio_man on May 5^th, 2009, 11:19am

hi there

i think it's down to the shape of the baffle (bit where the outlet pipe goes).

all the replacement tanks i've seen have different baffles to the original ford ones.

hth

Title: Re: Fuel sender gives wrong value
Post by amigafan2003 on May 5^th, 2009, 11:19am

With the tank full do a clock reset and see if that works (hold the trip mileage reset button in whilst switching the ignition on until the dials "flick" round).

Title: Re: Fuel sender gives wrong value
Post by tlundkvi on May 5^th, 2009, 12:04pm

on 05/05/09 at 11:19:53, amigafan2003 wrote:

With the tank full do a clock reset and see if that works (hold the trip mileage reset button in whilst switching the ignition on until the dials "flick" round).

I did it twice. The first time the dials flicked. The second time I started the car with the button pressed until a beep and discovered on-board diagnostics! First it lights up all elements on the lcds, then start pressing the reset button over and over. It showed the fuel level 54.6 litres, voltage, temp etc. Amazing! But it did not help, 15 litres would mean several centimetres, but I will drive and see if the sender reports the same value until it represents a correct level.

Title: Re: Fuel sender gives wrong value
Post by tlundkvi on May 5^th, 2009, 7:18pm

Here are some pictures of the leaking tank:

http://www.dessign.info/tank1.jpg

http://www.dessign.info/tank3.jpg

The stuff I smeared on the new one cost me 4 euros per kilo. Pennies for a car factory, and we wouldn't have to see these. Surrounding areas around the rear axle was virtually rust free.

Title: Re: Fuel sender gives wrong value
Post by harry.m1byt on May 5^th, 2009, 9:35pm

I would suggest there are just three possibilities....

1. Poor earth to the tank sender unit.

2. He bent the sender arm.

3. The float is catching on something as it rises (the baffle?).

Could you maybe fill it up a gallon at a time and see if the gauge suddenly stops rising suddenly, long before it is full?

Is the 'empty' reading accurate?
3.

Title: Re: Fuel sender gives wrong value
Post by tlundkvi on May 6^th, 2009, 9:28am

The third one seems more and more unlikely, as it decreases analogue according to what I drive (diagnostics mode shows now 49 litres and I've driven 40km since 54.6 reading). I recall it showed 60km to drive with exactly 11 litres in the tank when leaving the workshop (I fueled 59 litres as well). If the sender arm is not bent it should fill up to 35 litres at half tank.

One difference was noticeable, the lower part (that touches the spare wheel housing) was 15-20mm thicker on the replacement (Danish Klokkerholm tank).

Can the sender be calibrated somehow without putting resistors etc. in the wires? I hope high fuel means low value :)

Title: Re: Fuel sender gives wrong value
Post by tlundkvi on May 15^th, 2009, 7:39am

OK, now I've run a tank of fuel, and here is some data. The values from what the car believes the level is, are taken from the in-dash diagnostics.

Already when filling it up the first time, the volume of the tank was verified to be 70 litres, so this is not the problem.

Status	Car reading	Actual value	Difference
Full	57.3	70	12.7
Refuel now	9.5	21.5	12

The difference is constant. Might be the 0.7 litres went into the filling pipe. This would suggest a slightly bent arm, wouldn't it? I doubt the poor earth theory, as it would occasionally (?) show a good reading in tis case (I think). I didn't dare to run it to "20km left" status to get a true empty status.

Are there any ideas on how to calibrate this thing without taking the pump out and mechanically fix it?

Title: Re: Fuel sender gives wrong value
Post by tlundkvi on Jun 5^th, 2009, 7:26am

As the problem persists, I think I now know what is causing the problem.

The baffle is the same shape, give or take a centimeter or so wrt. height. Instead, the bottom of the tank is slightly more rounded and lower.

I was thinking, is there a chance that I've received a tank for the last facelift Granada, sold just before the Scorpio mk2? It fits, but the sender gives the wrong value, no wonder an error can occur in the compatibility charts. Now the Ford Scorpio/Granada text on the packaging occurred to me, but some say the tank is very different on the Granada.

So the question is, did the Granada (92-94 i presume), use the same type of fuel sender system as the scorpios (and almost all other Fords in the mid 90's)? I that case, instead of annoying trial and error bending of the arm to calibrate it, it would feel a bit easier to just put a Granada sensor in there with a closer calibration to the shape of the tank. If the rest of the system is the same too, I could swap the pump (known to be good) from mine to the (possible) Granada sensor assembly.

Can anyone confirm/reject this idea?

Title: Re: Fuel sender gives wrong value
Post by gozz on Jun 5^th, 2009, 8:52am

tlundkvi.
I think the hole in the Granada tank into which the pump/gauge unit fits is considerably smaller than the Scorp.As I don't have any Granadas left on the fleet,I can't verify it.The Granada up to K reg was definitely smaller.Obviously you will need to find a late one to look at,or talk to FMD.
GOZZ.

Title: Re: Fuel sender gives wrong value
Post by tlundkvi on Jun 5^th, 2009, 9:42am

Ebay items 250397555509 and 380076858859 seem to suggest these are pretty similar.