Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Dashboard Gauges

Hi everyone
It was a nice day for a drive and I was just outside Tamworth when I noticed the fuel gauge on empty though I actually had three quarters of a tank. Quick inspection with eye and nose and all seemed ok. Driving on and the gauge came back…….and then went again.

Following day gauge ok for twenty minutes and then showing empty……then came back for a few minutes or so and then went again. Then the temp gauge went awol as well. Next day the same again.

Every morning since I have turned on the ignition and the fuel gauge moves either a bit or goes to a correct position momentarily, then goes to empty. The temp gauge slightly flickers and has been ok on a couple of start ups on the drive

A Duratec engine, so far fuel and temp sender units have tested ok. Rear earth is ok as are the earths above and to the left and right of the heater vents.

So, dropping the dash is next but before poking around does anyone have any ideas as to where to look or what the problem may be.

I can live without a fuel gauge but does the temp gauge interface with the ecu to alter fuel mix for cold/hot engines and could therefore be a bigger potential engine problem? And how is a signal sent to the gauge? I’m afraid I cannot follow the wiring diagrams for this.

Having had years of no issues whatsoever I’ve both this and a steering rack to sort out. Such is life,

Thanks everyone.

Don't have a complete wiring diagram for that model but you seem to have checked the obvious at tank end. Is the gauge the bi-metallic type with needle moving slowly. If so there is likely a 10 volt instrument regulator behind dash which may be playing up. This would affect coolant temp gauge as well though.

Something to try Geof…

Unfortunately both the outputs to the fuel and temp gauges are processed by the PIC Micro on the pcb inside MFU. Maybe drop the dash and make and break both MFU connectors a few times. Probably best to disconnect battery first although I have gotten away in the past with hot swapping mine. The connectors can be troublesome but I doubt if the loss of the CAN signal to the temp gauge will affect the ECU's ability to manage the engine. The cylinder head temp sender has a separate connection to the ECU.

Good luck

I have this issue from time to time and find if I tap on the gauge itself it springs to life and shows what I was expecting. Not a fix but thought I would pass that along.

Those would be my first suspects. I have had an intermittent fuel gauge on the Roadster since buying it a couple of years ago. I have also checked the earths (they are OK), but my OBD-II 2 reader occasionally still tells me there's a problem on the sender circuit. One day when I'm feeling brave I will remove the sender and check it. I have used this product
https://www.amazon.co.uk/dp/B084CW1LZ9/ref=pe_27063361_485629781_TE_item?th=1
which is recommended for freeing-off sticky fuel senders, and it does seem to bring some life back to the gauge. I know the range is 250+ miles, so I brim it when re-fuelling and take care to find a filling station after 200 miles.

Reading the OP, it appears that both the fuel and temperature gauges are affected, so little point in pursuing senders etc as both are unlikely to fail at the same time.
Last year I experienced similar whilst in a traffic jam, with only fuel and temp gauges affected.. Switched off and started again and it was fine. Have since done a few 1000 miles and it hasn't reappeared. So I think it must be electrical/ECU based. First port of call has to be dashboard connections and instrument voltage regulator (unless that is also ecu controlled)

If it is like the S1 Roadster the fuel pump relay also supplies power to the ECU. They do wear out so it might be worth replacing it

John,
That's a new one on me, so is not something I've checked. Where woud I be likely to find it ?
Peter

Confirmed John, both S1 Roadster and Plus 4 of the period have the fuel pump relay feeding the ECU on pin 40 as well.

The relay concerned is second in from right on the bank of five.

Look under the dash on the drivers side they are up in the op corner if it is like my 2006 car.