Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Can I adjust a VDO fuel guage?

VDO fuel guage on my 1994 +4 never registers full (only goes to threequarters) and when off is way past empty. Can it be adjusted to give a more accurate reading, or is it the tank sender thats wrong?

I have been told that there is a small hole in the side of the guage and a small screwdriver can alter the guage. I was also told that you should first empty the tank and put in a small amount of fuel for the vehicle to run and then adjust the the guage to read empty. This will give you a good idea when to fill the tank when empty. I have not done this modification yet but will make it a winter project. I hope this helps.

David

Didn't know that David. My '98 did the same. I learned to live with it. Keeping a running log of fuel / mileage gave me a good idea when the tank was getting low...

Anyway, no longer have the car, just a very nice painting

Cheers,

When I bought my car ('96 +8)I was told that if it shows empty it's running on fumes and it never reads full, "they all do that sir"!
I've just got used to it and tend to refill at 1/4 full to be safe.

I don t know the set up on the Morgan but I would think the issue isn t with the dial but with the sender in the tank.

On Catheram, the system can be adjusted but is a paig of a job

Or maybe the issue is with the indicator hand on the shaft of the instrument? I mean the alignment of the hand on the shaft?

On catheram there is a deviice in the tank. There is a vertical bit and an horizontal bit

There are two things than can be adjusted

The level of intersection of both bits, so that this is roughly the half tank level

And the lenght of the horizontal bit so that its travel around the axe is as big as possible to have a fine measure

Both are known to be poorly tuned in Caterham, but I dismantled the system on my CSR and adjusted with a lot of car, putting in and out gas with an external pump by five liters iterations

Both mine have only ever shown 3/4 full

Thanks for that idea, I did take out the guage and have seen the hole, couldnt see any adjustment> might look for an old guage and take to pieces - anyone got one they dont want??

You can adjust your VDO fuel guage. I did it in August on my 1993 +8. It used to read 3/4 when the tank was full, and when the guage showed empty, the tank was still about 1/4 full, and I never knew how far below the empty mark it was safe to go.
There are instructions that you can download from the VDO website: http://uk.vdo.com (no 'www'). The relevant document number is 08 601 091 - if you put this in the site's search box and click the first search result, a pdf download will appear. It is written for marine guages, but they seem to be the same as the Morgan units, except they are waterproofed.
There is a small potentiometer in the guage, accessible through the small hole in the side at the top. It is quite difficult to see what is going on - I found it easiest to take out the guage and attach extension wires back to the dashboard wiring, and then you can peer through the hole left by removing the illumination bulb. You need a very small screwdriver - an ordinary household electrical one is too big. Wrap insulating tape round it to prevent shorting the potentiometer to the casing.
The idea is that you adjust the guage to the zero mark when the tank is empty. I preferred to take the sender unit out of the tank rather than to drain it. Undo the screws and withdraw it slowly to allow the fuel to drain out of it. No smoking!!!!!!!! I worked out that there is about 10mm gap between the the bottom of the sender and the tank floor, which would provide sufficient reserve, so I zeroed the guage with the float right at the bottom of the tube. Extension wires are needed here too.
So now I will know when the tank is nearly empty - but the guage still doesn't go up to the full mark when full!
I did the adjustment with the ignition on only - I am now wondering whether I should have had the engine running to generate a few more volts.

Hope this helps