At higher rpm my tach starts bouncing. It's on the money and steady until about 4500 rpm. When I am trimmed out and running 5000 rpm it's all over the place. I replaced the tach and the new one does the same thing?

Looked for the obvious loose wire and found nothing. Could this be a sign of a bad ground?

Are you hitting the Rev limiter? My old Checkmate would bounce at wot when it was hitting the limiter?

Not hitting the limiter, checked it with a tach that clips around a spark plug wire and I was right at 4950-5000 rpm when trimmed out. It starts at about 4500 and gets worse as the rpms increase. Under 4500 it's steady and accurate.

CHECK THE DIST CAP A BAD CAP WILL CAUSE TACH TO JUMP

JOE
AMERICAN PERFORMANCE MARINE
410-573-0057
[email protected]

Okay, now I'm gonna sound stupid but I don't think my motor even has a distributor?

It's a 2003 Volvo Penta 5.7 GXi

Mine does the same. Merc 575SCi
replaced cap & rotor same problem.

Still looking for a cure too

Mine was doing that last weekend. Spent about an hour touching every connection and trying to move every wire. I didnt find the loose groung I was looking for but when I ran the boat this weekend it was dead on. one of the plugs on the wiring harness must have been loose.

same problem on my playboy

"prongs of the cannonball plug"

you mean the doohicky in the whatcha-ma-thing?

laymans terms please... or ill just tell my boat wrench-a-thingy guy

I had the problem and the electricals shut my motor down. Ended up re-wiring the port side ignition and something near the distributor