View Full Version : Aqad31dplow rpmbs

07-19-2007, 01:56 PM
I have aqad31dp with a6 props. The max rpm's have been gradually dropping over the last year or two.There has been no change in weight or trim.rpm's are down from 3800 to 2500
any suggestions?

07-28-2007, 10:05 AM
"What size it the boat, is the bum clean, had a looked at the filters.....?
I run A5's on my SeaRay 280DA."

07-29-2007, 06:24 AM
The boat is a rosebrough 246 (24'6'').The bottom is clean.All filters were changed a couple of weeks ago.No change.

07-29-2007, 06:42 AM
"Disconnect the fuel return hose at the engine and let it run into a seperate container. Keep monitoring it and if it starts getting hot , getting less and disappears, You have a fuel supply problem.
It might be anywhere from screen at tank pick-up, filters, screen in fuel feed pump etc. As You do not mention problems getting it planning, I suspect it to be a fuel supply problem at top end. It might even be worn out fuel feed pump."

07-30-2007, 12:11 PM
I checked the flow on the return line and found a good flow at 2500 rpm"s(max speed now). There seems to be some air(foam) comming out of this pipe. Is this normal?

07-30-2007, 08:14 PM
"There should be no air comming, that might indicate an air leak somewhere in the system or 'boiling' diesel (vapors).
If doing an abrupt acc - does it smoke black when the turbo kicks in?
If not do a run and check again without the air-filter.
If possible hook a manometer and measure the turbo pressure.
2500 rpm is where the turbo normally should start boosting, but if that is not giving pressure, the injection pump will not encrease the fuel.(smoke limmiter)."