Tacho Not Reading Right

[Guest Roger 2B]

If this has been covered previously, apologies. I tried the search but didn't find the same problem.

 

Last week I had my car on a rolling road for a tune up and found that the tacho doesn't like high rpm. When it gets to around 4250 it stops and hovers around a bit round while the engine continues to 6000. At most rpm it is not steady but swings up and down.

 

It is a Smiths tacho, the engine is a Pinto.

 

Any suggestions?

[Guest Russler]

I had a similar problem when using a vdo gauge on my pinto, I fixed it by fitting a zetec instead, works fine now

 

p.s. sorry but never looked into it as the tacho was only fitted for three days beore I removed the engine

[IanS]

Earths.

 

Run a wire direct from the tacho -VE (often the body) to the engine and see if this helps.

Check that the engine to batery to body earth is large enough.

Check that the ignition module earths are good.

 

Ian