Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 My fuel gauge has gone Boris Johnson

The fuel gauge on my 2012 M3W was never very accurate but recently, it has started to go totally Boris Johnson (tells fibs and makes no sense at all). Today it was reading 11%, so I called in at a filling station. I managed to get 5½ litres in, in spite of much side to side shaking to equalise levels between the two tanks and much topping up of tiny amounts. The reading went briefly up to 80% but after just 15km driving, it is down to 49%. I am wondering if the breather tube for one tank has become kinked or blocked? It seemed worse when I got the car back from its total rebuild at Malvern but since has become even more illogical.

Any thoughts folks? Change the sender?

Wilson

Excellent addition to English idiom Wilson.

I'll do my best to include it in everyday usage.

Does sound like the sender has died the death, but it could be just the connections on to it being a bit loose or dirty.
Should be easily fixed for about £355 million so long as it doesn't take much more than a week!

I would also suggest checking connection to sender/earth and cleaning surrounding area first. Very vulnerable to muck.

sort of like being Trumped

I’m seriously contemplating replacing the fuel tank sender with a quick release cover plate and will simply check the fuel level with a dipstick clipped to the ash frame.

A bit of a faff taking out the plastic boot tray, but for me that’s no hassle. I only ever secure it with three knurled bolts these days

I have the longer sender unit, but it still shows 0% most of the time, which is absolutely no help if you forget to reset the trip mileage when you brim the tanks.

Why not a long flexible dipstick from the fill cap?

Does the sender earth through the screws from its cover plate or is there a separate earth connection? I have got a 2013 wiring diagram, albeit only A4 size so you need a magnifying glass. The sender appears from the parts book (V.5.2 - Fuel System Right - P.26) to be integral with the pump - part ref #6 unless it is what they describe as the "fuel tank dip pipe" - part reference #10 and this page shows the wiring (P.69 top right corner).

Wilson

The fuel gauge sending unit is a variable resistor.
Pull the sending unit, and remove the outer tube.
Inside are two parallel wires with a wiper on a float that connects the two wire. These wires oxidize and will create an intermittent connection.
Use some very fine sandpaper and gently wipe down each wire where the wiper makes contact with the wires.

I had the same problem and the fix was as describe above. The displayed level no longer jumps around... but I use the fuel gauge as a low I.Q. suggestion. When I get to 200 miles on the odometer, I fill up.

I always view the gauge as a "best guess", but trust the tripometer. However, it sounds like a little clean up on your gauge may bring it back to at least trying to guess