Trojan Boat Forum

Hi all...the starboard tachs on both the upper and lower helms in my F-36 are bouncing all over the place from time to time and then settle down...I don't really trust the reading at this point...I do know that they both give the same reading at the same time. 440 chryslers. Where do they get their signal from? What should I be looking at? Thanks for any help...

Check wire connections on back of gauges for corrosion...

Do the same at the coil

thanks guys...I'll start there...it just seems funny to me that both gauges up and down have same readings...

I checked all connections on the back of both tachs. I also replaced the coil because I had a brand new one on hand...both tachs still jump and eventually level out after a while...I'm lost

Try disconnecting one tach then the other (one could be shorting out the other ) also if you have points ignition check them .

So I disconnected each tach one at a time...no difference. I moved the cylinder selector a bit on each one and no change.

When I start the motors the starboard reads like 1000 rpms higher than it actually is. It bounces around a bit then eventually it settles down... I don't trust it once it does though.

Am I missing something???

Also what brand of tach did they use in a 79 f-36?

nice， Thank you.

I meant to put this in my last post do you have a engine synchronizer ? If so disconnect it and see

Targojoe wrote:Also what brand of tach did they use in a 79 f-36?

I believe my '79 F32 had DetMar gauges. Couldn't find any exact matches when I needed to replace some, so I have gone with Teleflex Red International series or Teleflex Amega. The look is close to the originals.

I'm using twin 318"s the electrical schmatic I have indicates a gray wire at the engin harness plug check the connection and drag test the terminal for tightness,secondly swap the ING module asuming the part numbers are the same. Could also back probe with DVOM at harness connecter look for a steady hertz reading or if it's fluctuing the same as the tach.
Regards steve

So the rest of us can learn did you solve this issue and if so how.

So far nothing has worked so in the spring I'm going to trace wired from the tack all the way back and go from there

There is a plug that attaches the wiring harness to the boat. I found it corroded on mine, could be contributor. The grey wire is for tach.

Well here I am 1 season later and I finally found the problem! It was the external regulator. The red wire had a chaffed spot that was causing the issue...it was affecting the continuity...I cut it out and repaired the wire...problem solved!!
Thanks everyone for the ideas