RPM issue

serpico1

I have a 2004 Rinker 312Fv with twin 5.0 Volvo engines and XDP Ocean Series drives.

At the end of last season, I had to replace both fuel pumps do to them being gunked up from the ethenol fuel being used here in NJ.

I've been having this problem since before replacing the fuel pumps, as I thought that the pumps were part of the problem. But that doesnt seem to be the case.  The issue is this, both engines appear to be running in-sync at slow speeds.  I do get the ocassional out of wack tachs, but a couple light taps usually corrects that problem. but, when I  throttle up the boat to get onto planning speed, thats when the engines go out of sync.  to keep the engines in sync, I push the port throttle to full open and the starboard throttle to about 3/4 full and the engines stay in sync until the boat gets up on plance. the the port engine starts running at full throttle and i then throttle back to the same 3/4 position of the starboard throttle to re-sync the engines.

 

Any ideas on why my port engine is not producing the same power as the starboard engine until after its on plane?  Could thsi be a simple throttle cable adjustment?