TR7 Fuel Gauge & Sender

[saabfast]

Think its Lucas we all love. Not sure who produced the printed circuit dash although I believe it was the first car ever to have one. Gauge just says 'Made in the UK'. I suppose it has lasted 40 years so not done badly really, although it does look as if the speedo might have been replaced before I got it in 2006 (wonder if the true mileage is more than the 87k indicated?). Bit of a Triggers broom!

[busheytrader]

And does your clock still work?

[saabfast]

YES! Now it does. It has not worked for a long time but I did notice it ticking round when I put it all back together. But that was yesterday, not checked today.

[FI Spyder]

While every one like to blame every electrical thing on Lucas, there is the story that they had to present three wiring solutions to BL for the TR7 before one was cheap enough to get accepted. Such was the English industry at the time. The other thing is to remember that we are dealing with 12V here and that the connections at the time were open and subject to wet and dry corrosion at a time when there was a lot of pollution in the air (remember acid rain?). When I first got my car I went through every electrical connection and cleaned it with contact cleaner with a pipe cleaner or tiny brush or rubbing it on a cloth (for flat surfaces) and putting the thinnest layer of dielectric grease on it. On the copper lands on the dash circuit I cleaned it with Brasso. I never had an electrical problem in the 15 years I've owned the car with two exceptions. A broken wire (at a crimped connector) that took 12V to the dash lights (I was playing around with the radio at the time) and battery wire clamp at the battery. As for the clock, some people have done the capacitor change in the clock, some have just cleaned the terminals at the clock. The clock being semi mechanical needs a good 12V feed and that includes every connection in the path from the source (battery) to ground. It can be hard to follow the path from circuit diagram to actual but if you do every connection then you know you have them all. A good winter time project. The other thing is the clock has a pendulum operation that can get stuck when connecting and disconnecting battery for what ever reason you might have for doing that. Just disconnecting and reconnecting will usually reset it to get the clock going again. That happened to me once. The clock keeps pretty good time having to reset it once every month or so (can't remember if its 5 minutes fast or slow). Keeps better time than my cell phone which I have to reset about once a week as the time/date goes crazy that often.

As the fuel sender is an analog system depending on resistance, any resistance on any connection in the circuit will skew the reading. That's not counting manufacturing/aging differences in the resistance coil on the sender to the gauge itself.

[saabfast]

YES! Now it does. It has not worked for a long time but I did notice it ticking round when I put it all back together. But that was yesterday, not checked today.

NO, checked this afternoon when I replaced a broken exhaust rubber ring and it has stopped.
I am assuming it is not a capacitor as it worked for a while, maybe just sticky but I am used to it only being right twice a day so will leave it for now. I have had it start when disconnecting/connecting the battery before too.

[CamGTS]

good to know that it is not just my clock that stops and starts. I've given up on it and I now just look at my wrist

[Beans]

In essence, the wiring and electronics on these cars are pretty good.
They only need some TLC after 40 years of use and abuse

[busheytrader]

So I’m not the only one left with a working clock?

I’ve had to replace my V8 Rev counter twice though.

And every time I’m in the car, I operate the headlight switch, flasher stalk and fog lights a few times or they become intermittent.