Fuel Sender Unit in Fuel Tank

(Timothy M Fox) #1


I had the unfortunate experience of running out of fuel in my newly acquired MKII. I was on my way to the petrol station with what I thought was 1/4 of a tank of fuel when the fuel pump started clicking quickly. At first I thought it was a fault in the pump or a major fuel leak but it was simply no fuel! You don’t realise how heavy these cars are until you have to push one.

Anyway, is it possible to recalibrate it by bending the arm of the float on the sender unit? The gauge goes right back to the left with the ignition off and now that the tank is full the gauge reads over “F”. If I bent the arm to lower the float that might fix the over and under readings, possibly?

Or should I just replace the Sender Unit?



(Andrew Waugh) #2

First off, check if your IVR output is 10V.

Second, check the calibration of the gauge (http://www.mgb-stuff.org.uk/fuel.htm).

(Ian) #3

Well you know it works ok , so I would just bend it , so just on full , then Carrie a fuel can in the boot , just in case !

(Timothy M Fox) #4

Thank you for that information Andrew.



(DaveMoore) #5

I always carry a 5 liter plastic gerry can in the boot…

(Timothy M Fox) #6

Hello again,

I found this in the Jaguar MKV Service Manual and the principle would be more or less the same.:blush:



(Paul Breen pay palled it) #7

Amen to that. I carry a 6 in mine. Paul

(Rob Reilly) #8

I always carry an empty one because the gas stations don’t loan them and charge an awful lot to buy one. Also a rubber bungee cord to hold it in place, because I once had a full one fall over in the trunk and spilled all over, what a mess.
I just noticed in Tim’s Mark V reference in the first sentence that it says “single wire”. This was true of Mark IV and earlier models, but not of Mark V, which had two wires. Someone failed to update the paragraph. One wire is for the gauge and the other is for the low level light. The green/black gauge wire test is as written. The green/yellow low level light wire test is to touch it to ground and the light in the gauge should come on.

(Timothy M Fox) #9

Hi Rob,

Thank you so much yet again as that explains the issue I’ve been having with the MKV fuel sender unit and the low level light. Both are faulty with the sender not registering accurately and the warning light being on permanently! Both jobs are further down the “to-do list” at present but you have helped me even before I get there with your information. I would have been quite confused when I got to it, seeing the two wires contrary to what was written in the Service Manual!:thinking: