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MG Midget and Sprite Technical - Fuel gauge inop - need help soon

My 79 1500 has been sitting for awhile and I need to get it on the road soon. I am deploying again the first of the year and my wife is threatening to sell the car instead of moving it next summer to our new duty station. I have a handful of issues, I'll start with the fuel gauge.

Gauge hasn't worked for years. Always higher priority items to fix. I have done zero troubleshooting on it thus far. Read through many archives and couldn't figure out where to start. Gauge has been stuck on full empty regardless of fuel level.

Mechanical stuff I a not bad at; electronics I am lost.

Any idea on what to do? My hazard lights don't work either and turn signals are intermittent. Not sure if they are related.

Thanks in advance.

Trig
Trig Lennard

Do you know how to use a 12volt test light?
Got same? And/or a cheap multimeter? Get them; parts store or Harbor Freight $10.

List all issues and history, so I can see what might point to common fail points. There is some interplay of haz, TS, and Fuel gauge, plus wipers, heater blower, etc all the stuff that works only with Key ON.

Hope you are kidding about wife!

FRM
FR Millmore

I have an Analog Multimeter I used for fixing a washing machine once (black and red probes with analog display).

I am military and we have moved the car around the country for 20 years. My wife is about tired of it so I need to get it running. I'd like to get it in shape for her before I leave for Afghanistan.

History. Lots of current electric problems but the fuel tank has been the longest inop. Tach works as does the miles. I've taken out the heater so the fan doesn't work and I currently have the console out to give me room. However, the fuel gauge failed before I removed the console so I don't think they are tied. Hazards don't current work although my turn signals work (most of the time).

I have never done any work with electronics and wires. Lots of time with other issues but always avoid this. I've done no work with the fuel tank so I assume orginal parts in the tank.

Not exactly sure what to do with the multimeter. What other information would help?

Thanks, Trig
Trig Lennard

Trig -
Send me an email to above. Include phone - this takes far longer to write than to speak, at least as preliminary.
If you can read somewhat complex stuff, I will send you "Electrobabble" too, which will give you the entire basis of operation and troubleshooting, including how the meter is used.
Do you have a wiring diagram for the car?
If not, somebody will provide a link to an online one - I don't keep track of such usually.

It is all very simple logic. And it is "electrics" rather than "electronics" which are different and far more nefarious devices, spawn of the Devil!

FRM
FR Millmore

Thanks FRM. Email enroute shortly. I'll break out a couple of my manuals and see if I can locate a wiring diagram.

Trig
Trig Lennard

Trig, could be a fuse or loose connection. On my car. it had sat for so long (10 years) the fuel tank sending unit had seized in the half tank position. Replacing it was the only cure for it.

That might be your problem as your car has sat for some time but the gauge itself could have failed too.
Clive Reddin

Hi
My car is much older than yours but in mine, if the wire running from the sender unit to the guage is inadvertenly earthed, then the gauge shows empty. If the wire from sender is broken (but not earthed) at say a bullet connection, then it shows full. Or is it the other way round?
If your gauge is of the same type, but perhaps not as your's is a later car, then it is quite a straight forward job to track down where the fault is, and whether the guage is working.
Graham M V

Thanks. It isn't a fuse (at least not one I can find). I suspect either a wire or the unit in the tank. Not sure how to "chase wires". Breaking into the maintenance manuals now to look at the diagrams. I think I have a few bad wires (intermittent signals, no hazards, etc). Just have to figure out how to find them. Hoping not to have to drop the tank. Never done it and I imagine it isn't easy.

Trig
Trig Lennard

Trig-
Sorry, got crazy busy, forgot to call you. Will try tomorrow. You are describing bad connections of the White/Green fusebox wires, and the fuse and connectors in the fusebox which are notorious for having bad contact. Remove the fuse and clean the ends and the clips it fits to. Measure the voltage from the W wire to the G wire(s). Should be zero with all Ignition switched accessories ON. If more than.025V, the fusebox rivets holding the wire tabs to the fuse clips are usually loose. Draw how all the wires are fitted, and which end of the fusebox is UP, remove it, set the rivet on a punch in a vise and smack the other end with another small punch and hammer to tighten the rivet - usually fixes it.
Or replace the fusebox, but they are dear.

FRM
FR Millmore

This thread was discussed between 04/08/2012 and 07/08/2012

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