Tach problem?

[cigars01]

I have Twin 454 350HP Crusaders. Per the serial numbers the blocks are from 1978-1990. The engines were installed in the boat (rebuilt I am guessing) in 1999. They have 370 hours on them and run fine. This past weekend went out no problem. On the way back the in 2 days later the port tach showed much higher rpm than starboard. The synchroniser showed them to be in synch. I opened both up just to see and port engine showed 5000 and port was normal about 4200. The engines sounded the same so I am reasonably sure the probelm is not the engine. Is the problem the gauge or the sending unit. I would think if the sending unit was bad that the synchroniser would be off as well which it does not appear to be.

 

[electricaldoctor]

Try removing the tach and move the 4-6-8 switch back and forth a few times. This wiping action will clean up the contacts and sometimes that will cure the problem. It has worked for me in the past. Don't forget to set it back to 8 for your engines.

 

[cigars01]

Great. Thank you. I got the same advice from another group that I am in. Its nice when the experts (which i am not) agree on how to fix a problem.

 

[LUnaCY]

Moving the switch around worked for me as well.

 

[Kasper]

Moving the switch around worked for me as well.

Worked for me also.