Show whole topic May 17, 2020 9:39 am
h14 Offline
Member
Registered since: Nov 30, 2008
Location: Chalandray, France


Subject: Re: Fuel senders
Hi David,
I believe the sender in my Riley RMB has an 85 ohm resistance, so 60 sounds fine. Reading your detailed findings, the gauge works, and I think you're saying that when the float is moved, you get a reading traversing from 0 - 60 ohms. If that's the case. I suspect your problem is a poor connection between the sender unit and earth.

On my V12, I see a secondary wire has been added from the sender unit to the tank body, so it's not a rare problem! Indeed, as tanks are flexibly mounted via non-conducting materials, ie rubber and canvas, the actual earth path is primarily via the copper petrol feed pipes. If they've been replaced by plastic, there's your problem.

In all cases the best resolution is to run an earth wire from the body of the sender (or of course earth terminal if it has one) to the chassis. If like my V12, there are plenty of screws into the chassis, for example holding clips for the loom, and petrol piping, that a terminal could be fixed to. Ideally, clean the chassis to bright steel and place the terminal first, before re-attaching the screw, washer & clip.

Laurence