TechMod :  XJ900S Fuel Gauge Sensor Repair
How to repair your Yamaha Diversion XJ900S Fuel Gauge Sensor
Yamaha Diversion XJ900S Fuel Gauge Sensor

Unfortunately a faulty fuel gauge on a Yamaha Diversion XJ900S is a case of "They all do that mate". A new one, part number 4KM-85752-01, is expensive (around € 84,00) but with a bit of 'DIY' it is possible to repair it yourself. This repair scheme has been written by Keith Straw (Keith's Original Guide) and Michel Deventer (Michel's Approach) who has also added the pictures. Some of the original pictures have been replaced as your webmaster had the same sensor problem but replaced it by a new part.

  Keith's Original Guide

The problem is that the pivot of the sensor arm wears to an oval section allowing the arm to move sideways. This pulls the sensor feelers off their track with the result that the fuel gauge stops working. If left in this condition too long, the feelers which are very fine slips of metal will break making the device unrecoverable. However, if the feelers are still in place, it is possible to repair the pivot. Remove the fuel gauge sensor and disassemble it. Measure the thickness of the pivot arm. It should be about 2 mm. Buy a piece of brass tube of the type used in radio control models with a bore of 2mm. Take the pivot arm with you to check the fit. It is available from most good model shops Europe-wide.

The next part is tricky. Either: Use a very fine drill (about 2.5mm) to drill out the original pivot tube to accept the brass pipe. Or cut the original pivot tube off and use an epoxy resin glue to glue the brass tube in its place. You might also be able to braze the pipe into place if you regularly build model railway engines and have that sort of skill of hand! You can then reassemble the fuel gauge sensor and reinstall it.

  Michel's Approach

I've used a slightly different approach. I've drilled out the original pivot tube using a drill 1/10 mm smaller than the width of the replacement pivot tube. Then I've used waterproof sandpaper (grain P600) to match the width of the new pivot tube and the drilled hole. (so I've actually sandpapered the new pivot tube, but only for a few 1/100 mm) After that I've cleaned the lot and put the new pivot tube in its place by using a small and light hammer.

I was not able to braze the new tube in its place! The two parts kept breaking off.

Finally I've used epoxy resin to glue the arm onto the plate and into the new pivot arm. The arm, the plate and the pivot tube now end up being one single component.

  Marcel's Approach

Na herhaaldelijke ergernis aan het niet goed functioneren van de benzinemeter op de Diversion 900 heb ik besloten om een serie nieuwe busjes te draaien. Na het leeg laten lopen van de benzinetank kan men beginnen met het verwijderen van de vlotter en de sensor. Ga dan als volg te werk:

Met behulp van 2 kleine schroevendraaiers wipt men voorzichtig de aszegering van zijn plaats zo dat men de vlotter met zijn stang kan verwijderen. Vervolgens demonteert men het aluminium onderdeel uit zijn kunststofbehuizing (wees voorzichtig met die kleine sleepcontacten). Zaag voorzichtig de versleten bus er af en boor met een boor van 3,9 of 4 mm het gat op. Doe dit niet met de hand maar onder een boorkolom. Vervolgens tikt men de nieuwe bus met kartel (met behulp van LOCTITE 270) in het uit geboorde gat. Let op de uitsparing onder in de bus voor de stang van de vlotter. LOCTITE uit laten harden en vervolgens monteert men de vlotterstang en de aszegering (liefst een nieuwe) op zijn plaats. Monteer alles weer voorzichtig terug in de tank en sluit de stroom connector en de benzineleiding weer aan. Denk aan het open zetten van de bezinekraan.

Marcel klein Goldewijk

  Pictures

Complete assembly
Close-up of the fuel gauge sensor
The problem: Sideways movement lifting the fingers off the track
Close-up of the tiny little "fingers"
Close-up of the circuit board
This is what is causing the trouble
Another mistery solved. For some reason the fuel red light on the dash kept working properly. This second sensor is at a fixed height in the tank. If the fuel level drops below this sensor, the light will come on.
The new pivot tube in it's place
Other side

Last update 30-Jan-2008