2003 5.7 Volvo Penta SX Sudden and Intermittent loss of top end

[Dragotech]

Boat is a 2003 Glastron 215 DX. Engine is carbed. We have owned this boat for a couple of months and have had no problems with quick lake runs. First time we took it out and ran it for an hour straight, we suddenly lost top end rpm, down from 4k to 3k. Oil pressure and temp remained normal. When we brought it home it ran fine on the hose. I took it out again and had full power for five minutes before experiencing the same symptoms. We took it back to the shop where we bought it and they could not duplicate the symptoms, although they did adjust the timing. The next time out on the lake it ran for 15 minutes until experiencing the problem. This is the worst possible time for us to have the issue because all the repair shops are slammed and we have a river trip planned for the end of next week. Anyone have any ideas on this?

 

[yamatech43]

Re: 2003 5.7 Volvo Penta SX Sudden and Intermittent loss of top end

Get a vacuum gauge from auto parts dealer(very cheap), get a piece of clear vinyl hose(3/8" x 8"), and a 3/8" barbed fitting, install the vacuum gauge inline on gas line just before filter(engine) and run it. Vacuum should stay below 2" at idle and under 5" at Wide Open Throttle, preferably below 4.5"....suspect you have vacuum building up(first guess anyway from symptoms) this may be caused by clogged vent on tank, restricted fuel line, improper setup, trash in tank getting around pickup.....you may as an alternative run it on a portable tank and see what happens.

 

[Maclin]

Re: 2003 5.7 Volvo Penta SX Sudden and Intermittent loss of top end

A simple thing to try is remove the gas cap when this occurs, listen for a whoosh of air, that would indicate a clogged vent that yamatech mentioned. If that is the problem then this is also a way to get going again quickly.