Check this out , I had a similar issue and this is what I did.   https://foc-u.co.uk/index.php?action=downloads;sa=downfile&id=67

hi there , i have a 2001 fzs600.  this fuel gauge has played up before but was cured simply by disconnecting fuel reader connection block spraying wD 40 into it and ridding the furring ( ver de gris ) off the connections and it was working perfectly again.  this time possibly coincidentally as a result of needing to temporarily disconnect the battery to do  a different job entirely , found the fuel gauge which worked before was now not working properly , that is to say not working as it should !  i have checked for the same issue as first time , all clean still and no reason to suspect similar reason as before .
the tank is about 70% full yet the fuel gauge will slowly climb up to the first mark above empty and no more , the needle drops back where it should  when ign off, so it is operating but not normally ( if were allowed to use such a word these days  [size=78%])    [/size]

what could be the reasons and solutions ? how would i verify the faulty items ?

in the interim two questions,

although the gauge wont go any higher than first mark , would it react normally when fuel is lower than where its reading right now?

does the fuel warning light depend on working fuel gauge?  is it linked or independent to the fuel gauge , in other words can i rely on the fuel warning light despite faulty gauge ?

just thought of a third question now , when fuel warning light does come on , how much fuel do you have left ?  obviously fuel up immediately but what does the fuel warning light represent in mileage terms ?


thanks anyone who responds   

I paid by PayPal so I’ll go through them. I think I need to give them a couple of days to respond. I wrote to both parties yesterday.

The switch you suggested turned out to be the wrong one, two plugs with two wires each. I couldn’t get to the bottom of what ‘stuff to turn’ meant and it was an uphill struggle trying to find out if it was any better than mine. I wasted 5 days writing and responding and getting the same replies. I just gave up.

This hasn’t gone to plan. I was expecting delivery by 4th April. I checked FedEx website on 5th to see they claim they delivered the switch in 2nd. Clearly not the case both my wife and I were home all day. So I’ve paid £194 for the switch and £42 customs with nothing to show. I’ve contacted both supplier and FedEx but heard nothing back yet. Very frustrating. 

Assuming you paid by credit card, file a visa chargeback on the seller with your bank. Make sure to email a copy of all corrispondance shwoing to tried to resolve it to your bank.

Ok. obviously rewired with minimal wiring. Look at the underside of the relays and put the numbers to the relevant wires on your diagram and I will show you how it works on your diagram

Attached is a picture of the two most common relays you will get at the Motor Factors with the inner workings shown