Vacuum hose to MFA

[scirocogtx]

Quick question, does the vacuum hose to the MFA control the revs and rev counter reading or is it electrical?
I have a faulty rev counter and having checked the earth strap to rocker cover it is fine.
My next step is checking the vacuum line if it is involved, followed by examining the cluster.
Thanks

[Nate]

Rev counter just has a connection to the coil, and it counts the sparks

[scirocogtx]

Ok, that sorts out my next move.
Thanks.

[Nate]

Have a look in the Haynes comic to see what colour the wire is from coil to tachometer. I think its blue, which probably means it isn't blue. If you've got a meter that will count pulses, check coil output (low volts side, obviously) then trace the wire baack and look for the same reading.

obviously there is the potential to give yourself a good shock playing with the coil when engine is on, so make sure insulation on the king lead is in goodnorder before you start, and be careful. Vzzzt!

[ianaudia4]

Check the blue pcb on the back of the clocks for any breakages. The vacuum hose for the MFA controls the MPG readout.

[scirocogtx]

Checking the pcb for breakages and any broken solders was my next move.
If I dont see anything obvious I will try and look for a voltage drop from the coil to the board. Will be extra careful..
Problem's been annoying me for a while, that and no MPG reading on the MFA! Looks like I will need to check the vacuum line too.

[ianaudia4]

Do you have no reading on the MPG, not even 99.9?

[scirocogtx]

Do you have no reading on the MPG, not even 99.9?

Sorry, yes thats what it's reading

[scirocogtx]

Have a look in the Haynes comic to see what colour the wire is from coil to tachometer. I think its blue, which probably means it isn't blue. If you've got a meter that will count pulses, check coil output (low volts side, obviously) then trace the wire baack and look for the same reading.

obviously there is the potential to give yourself a good shock playing with the coil when engine is on, so make sure insulation on the king lead is in goodnorder before you start, and be careful. Vzzzt!

Will a 'normal' voltmeter give an average voltage reading across the coil and across the tacho? I assume the pulse is quick?
If so if the values match this should show that there is the same voltage passing between the two. Is this right?

[ianaudia4]

Do you have no reading on the MPG, not even 99.9?

Sorry, yes thats what it's reading

Hopefully it is just the vacuum hose.

[Radorocco]

I seem to remember a few 99.9 posts on the Corrado forum. I presume the basic principle is the same.

I"ll see if I can find anything

Cheers
Jeff

[Nate]

Have a look in the Haynes comic to see what colour the wire is from coil to tachometer. I think its blue, which probably means it isn't blue. If you've got a meter that will count pulses, check coil output (low volts side, obviously) then trace the wire baack and look for the same reading.

obviously there is the potential to give yourself a good shock playing with the coil when engine is on, so make sure insulation on the king lead is in goodnorder before you start, and be careful. Vzzzt!

Will a 'normal' voltmeter give an average voltage reading across the coil and across the tacho? I assume the pulse is quick?
If so if the values match this should show that there is the same voltage passing between the two. Is this right?

Nope

[PeteGLi]

Have a look at the 'Multi Function Indicator' in the FAQ section. Might help you narrow down where the fault lies. Unless the vacuum tube is split or not connected, I would suspect that the little sensor unit on the back of the clocks may be at fault.