Rev counter playing up

[zavala]

I've got an 92 Izusu Mu 2.8td, today the rev counter decided to play up, at 100kms it's saying 3500rpms, normally it reads 2500rpms, at idle it's sitting on nothing, normally at idle it'd read just under the 1000rpms. Got in it later in the day and it starts of normal then goes silly again,
Any ideas any one?, also how hard is it to fit a after market one?

[geeves]

Its electric and runs off the pump. Could be worth unplugging and replugging the connectors to get rid of corrosion. No aftermarket tachos will work

[dasnoboarder]

Would an aftermarket tacho not be able to read the signal from the fuel pump Geeves? Like it would on a petrol's coil or ignitors? ...Just for future reference haha.

[geeves]

It works a different way. No pulse to read

[dasnoboarder]

Ok, cheers.

[zavala]

thanks guys, I'll give this a shot, will post what happens

[Demonic]

Ive got the same problem, wheres this plug?

[mudslinger]

right against the block just above the pump its a brown plug from memory i think 2 pin

[oompalompa]

dont know if this helps or is worth a try, i had a 89 bighorn and the rev counter would work intermitantly, then other gauges and lights stopped working. auto sparky changed the charge relay under the hood and fixed all prob. bighorn maybe wired differently to mu , not sure but could be worth checking out.

[haven]

wondering if this is the problem with my mu as im not convinced the tacho is entierely accurate... dont see how corrosion in terminals would cause incorrect or intermittent faults though..shame we cant juts slap on an aftermarket one easily