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Tachometer not going above 2800 rpm


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1983 1.8S Berlinetta, Engine revs freely and runs fine aprox 90kmiles. Rev counter sticks at approx 2800 rpm. Any suggestions please?

(do not say put your foot down. Speedo rises no ptoblem but tach sticks at 2800 rpm)

All electrics OK as far as I can tell. Green wire on coil looks ok.

It has a Lucas coil not the original Bosch one, could that be the issue ? Is the ignition module likely to have any effect ?







Edited by dog321fish
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Hi. The  fact that the engine itself runs fine and has no issues regarding rev limiting and acceleration points to a problem with the actual tacho itself.the tacho gets its signal as pulses from the green wire and intertpets that as a rev speed.it sounds as though either the needle itself is sticking or the unit is faulty.

you will need to remove the instrument cover 'hood' and then the heater levers and light switch plugs to get access.

the top will swing out to one side.you can removeit completely by unclipping the heater cables but you prob wont need to.

once you are inside lift off the cover and  the tacho is held in with a couple of srews and lifts out leaving all the rest in place. 

Check it for sticking or just pop another in to try. Should be plenty about,confirm correct type regarding colour of needle / typeface style .



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Should be plenty tachos around then .ive seen a few breaking ads on here. All manta b / ascona b/ cavalier mk1 ones interchangeable electrically .early up to about 82/83 orange later ones white etc. As I’m sure you know.

nice to hear you’ve had car from new. Nothing better than knowing a cars full history.

all the best 

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1 minute ago, dog321fish said:

Well I managed to get another rev counter, it looked good, fitted it at the weekend and the needle goes all the way around and stays there, which is much worse than my original, any suggestions please ? 

Sometimes if they haven't been used for a while they stick. If you tap the dash top you can usually un stick them.

If you're lucky a bit of use and it will be fine.

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Hi. So you have got another but the needle just goes round to max on its own ? Or goes up when you rev it and sticks ? 

If its the latter it just sounds like a stiff spot or maybee the needle is rubbing .?. It sounds like you are one of the very few who have had any sort of issue sith a tacho. Two bad ones after each other is certainly unusual in my experience.

the tacho has a 12v feed and an earth(negative) and a signal pulse taken from the green wire .so theres not much realy thatcan go wrong.all supplied by the three pins that plug i to the dashboard.

did you try the original for stiffness / freedom of manual movement ?

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Needle went round to max as soon as I turned the ignition switch on and stayed there regardless of revs, on a plus the seller is swopping it for me. I have not fiddled with either of them for fear of making them worse. It is really a summer car so no rush to get it fixed, Thanks for all the help.

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Ok no worries. 

Still a strange one thou.

 One thing worth checking whilst the tacho is out although like I said I’ve never had any issues with any before is to make sure you have 12v to one of the three pin sockets ( sorry can’t remember which)in relation to body earth AND the 2nd pin.  And that you have continuity between the remaining pin and the green oil lead.

can remove mine to confirm pins if realy required but I’m sure you get what I mean.

also the pin outs may actually be written on the tacho itself ?     Probably +.  -   I. Or T  ..?

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