Fuel sender reversed

[Quinten]

So I've got my nice new fuel tank, and my nice new fuel pump

(shown before the tank was modified)

and it looks lovely in the back of the car...

 

However, now I've got it all connected up, I have discovered that the integrated sender on the pump (VDO) shows as full on my gauge (VDO) when empty, and I'm assuming empty when full.

So, I was just wondering if 1) there is something cheap off the shelf that can be used to correct this, or 2) i could use a spare Arduino and make my own converter?  I've seen the Spidya website, but the prices put me off, and I've seen this gadget which may work if the range matches my sender/gauge, but my inner tinkerer tells me to utilise the Arduino for it...  @Kit Car Electronics would probably agree  

[Thrustyjust]

Make 2 stickers for the gauge and swop full for empty and vice versa  Job jobbed !!

[TableLeg]

Quinten,

I am not familiar with that pump with integrated sender, what does it use as way of a float? Is it an internal type in the body or does it still use a float on a pivot arm on the outside of the body?

If the latter, can the float arm be modified to pivot in the opposite direction?

 

[Kit Car Electronics]

1 hour ago, Quinten Uijldert - Northants AO said:

 

So, I was just wondering if 1) there is something cheap off the shelf that can be used to correct this, or 2) i could use a spare Arduino and make my own converter?  I've seen the Spidya website, but the prices put me off, and I've seen this gadget which may work if the range matches my sender/gauge, but my inner tinkerer tells me to utilise the Arduino for it...  @Kit Car Electronics would probably agree  

I agree 

Like this?

[Quinten]

50 minutes ago, TableLeg said:

Quinten,

I am not familiar with that pump with integrated sender, what does it use as way of a float? Is it an internal type in the body or does it still use a float on a pivot arm on the outside of the body?

If the latter, can the float arm be modified to pivot in the opposite direction?

 

That's the unfortunate bit.  The sender has a float arm, and due to the depth of the tank, and the internal baffles, the pump was mounted in such a way that the arm could go up or down in between the baffles.  I'm 99% certain that the arm could only be mounted in one way (and not the other way around), but even if I could reverse the pivot, the pump would have to be reversed too, meaning it would 'point' towards the rear of the car.

 

14 minutes ago, Kit Car Electronics said:

I agree 

Like this?

Oooh, please do share more (if you can?) 

[Kit Car Electronics]

mine reads 0 when it sees 9 Ohms (82mA) and reads 4/4 with 102 Ohms (52mA). Short to ground reads very empty and open circuit reads very full.

The gauge is basically an ammeter, so it should be possible to control the current with a PWM N-Channel MOSFET. You'd sense the fuel sender by wiring it to ground on one side and to an analogue input pin with a 220 Ohm pull-up resistor to 5V. You could calibrate the whole thing to read perfectly through full scale, and add a filter to damp any sloshing.

[Quinten]

Cheers Mike, that should give me enough to go by for now.  I know my gauge is 10-184 Ohm (VDO white cockpit), so just need to measure the sender (it's near empty now, so ideal for measuring that value ).

[Quinten]

I chickened out!

 

After I filled the tank up to the brim I was peeved to discover that my gauge barely moved.  If it was indeed a reverse sender, I would have expected it to go to empty (when full).  So I had a little brain storm and bought one of these usb inspection cameras for £10.99 as I was thinking, what if my float does not move freely and is stuck against the baffle.  Plugged it in on the laptop and had a look around, but due to the extremely short focal area could not really see what was going on.

So out came the pump today and then I started to think, why not disconnect the fuel sender and replace it with my old (matching) sender?  Took forever to mount the thing on the pump, but I now have a working fuel sender again 

[Captain Colonial]

I was just about to suggest rotating the gauge in the dash by 180 degrees.  Glad you sorted it though.  

[Kingster]

I need to fettle my sender as it doesn't bottom out fully. So reads empty when there's a good 8 litres in it. 

Never bothered me with an analogue gauge - but now I have a fancy pants digi dash that tells me how many litres I have left (but lies) as well as a warning light (that comes on too early), it somehow annoys me!

[Northwarks]

I fitted the SPA digital gauges 2 years ago and I still can't trust the fuel sender, on my second VDO Dip/tube sensor and it still foxes me as the fuel drops. I added a 100ohm resister over the winter to try and bring the resistance into the range of the gauge  - has 5 calibration points which are proving to be the challenge, does ok until about 1/2 tank then it all goes downhill from there showing anything from 1/2 to empty

 

[DamperMan]

Is it progressively emptying or fairly binary.    Some have the fuel light switch on the sender as well as the gauge, that would give you full fuel when empty and empty anything over empty.    I think most westfield fuel gauges are a a rough guide!.   Mine tells me when its full it is full, once it goes below half way its a guess. I tend to look at the trip meter and if its more than 100 miles its time to stop at the next garage.    Tip of the day........ If there is a mini pavement around the pump, drive past the pump a little  then reverse so the driver side rear wheel is up the pavement.    It makes brimming the tank so easy.