A3 8L Fuel Pump Sender Unit

dirtychinchilla

Registered User
Morning guys,

I need to replace the sender unit in my fuel pump, and I've not been able to properly find out which part I need. Could anyone confirm for me that this is it?

Thanks,

dirtychinchilla
 

newbster

Registered User
That is the same part i'm watching, and is the "sender unit" for the fuel gauge, if that's what you want

if you don't mind me asking, what is the problem, my gauge is very non linear, does about 400 miles to the 1/2 tank line from full then just rockets down to empty
need to vag-com on it to confirm its the sender
 

dirtychinchilla

Registered User
So you're certain that's the correct sender unit?

Mine isn't quite the same issue as yours. My gauge works correctly as it's been tested with the diagnostic machine, but it always reads 1/8th higher than the fuel level actually is, so the warning goes off st the wrong time etc
 

newbster

Registered User
not 100% certain, I was going to drop them an email before purchase

there is an offset for the fuel gauge stored in vagcom somewhere, if its a constant offset that might dial it out for you
 

dirtychinchilla

Registered User
Sorry I haven't replied sooner. I did email them, but never heard back. Did you have any luck?

It's for the 1.8 petrol, so I don't know if that will make a difference as mine is the 1.9 diesel...

Does anyone know whether this will work?

Interesting about the offset, but how would you know exactly where to set it?
 

dirtychinchilla

Registered User
Fair enough. Thanks for the guide - I think I'm going to ask my mechanic to do that, because that's probably the cheapest method. If it doesn't work then I may just get a 2nd hand pump from eBay and use that.

Practically, if you use the offset then how do you know how far out the gauge is reading?

By changing the offset, do you know whether the beep for low fuel will change it's timing too? ie. mine goes off at 1/4 of a tank according to the gauge, but as far as I remember, it used to happen at 1/8th when you get into the danger zone. Would this automatically change too?
 

newbster

Registered User
post 15 in the link
AFAIK, the compensation is linear and affects the whole scale, so if you shift the needle position higher, you'll also shift the position that the gas light comes on. That's why the calibration is typically done at the level of the reserve tank, which is 1.85 gals. Remember that you can only adjust the needle by +/- 2L (0.52 gals),
 
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