Lotus Elan and Lotus Elan Plus 2 Forums

Recently had the original tachometer in my 66 Elan S3 rebuilt by Nisonger Instruments in NY - I left it as positive ground, but it was upgraded to allow a negative ground conversion later. Tacho has worked fine for several months until recently when both engine mounts were replaced. The tacho worked fine when I left the shop, but when the car was started about 20 minutes later, the dial registered only 200 rpm on idle and wouldn't go above 600 when revved well above that. Checked connections at the coil and dash, which seemed ok. Any ideas as to what might have caused this?
Thanks.

How are the earth/grounds from the engine?

Send it back under warranty for checking!

Nisonger repairs has shut down after one of the storms last year flooded their shop.

I agree w/ anther poster that you should check the ground around the motor mounts. The mounts are rubber and do not carry current well.

Roger

Thanks for the responses. The grounding strap seemed ok visually, but I'll check the connections more closely. If this was an issue, wouldn't it also potentially affect the spark plugs from firing properly?

I initially spoke with Nisonger looking for some guidance and was told that after the flood shut them down last September they stopped doing repairs/rebuilds, although they still sell new gauges. It didn't occur to me at the time to ask about warrantee, I imagine at this point it could be a struggle.

Jon

If you feel you need to send it off somwhere, try https://momamanufacturing.com/

I've had excellent results from them.

Thanks, I've read good reviews for them.