I have a '89 Pro V on a '88 Ranger 390, which has always ran very strong. Recently I noticed that it would run 1-2 minutes at 4500-5000 rpm then dye down to 3500. The other day it would get up on plane, hit @4000 then drop off to 2500 rpm. When I bring it back to idle, then hit it, it goes on plane then drops to about 2500 again. I'm up in Kalispell Mt and Yamaha dealers are few, much less the guys who have worked on older Pro Vs. Am I looking at a fuel pump issue here, or something much worse? I'd appreciate any input.
Announcement
Collapse
No announcement yet.
Pro V losing power
Collapse
X
-
-
Originally posted by Jason2tpa View PostMan, great question rodbolt. Never occurred to me that altitude affects engine performance. I assume because of the thinner air?
Guys, this lake is about 2,900 feet above sea level. What would you have to do to get best performance at this altitude? Is there a certain altitude where changes become necessary?Last edited by cpostis; 08-11-2016, 12:25 PM.Chuck,
1997 Mako 191 w/2001 Yamaha SX150 TXRZ Pushing Her
Comment
-
Reply
I don't run much on the Flathead, but it is a nice lake. And it did run real strong until the problem. I do believe it is a genuine Pro V. Actually bought it @ Quaker Marine in Eastern PA as new years ago. Since then we migrated west. And the altitude does make a difference, it runs richer , w/ less power than it did on flatland.
Comment
-
Originally posted by Jason2tpa View PostMan, great question rodbolt. Never occurred to me that altitude affects engine performance. I assume because of the thinner air?
WHY DOES MY BOAT PERFORM DIFFERENTLY ON A HOT DAY VERSES A COOL EVENING?
It is a known fact that weather conditions exert a profound effect on power output of internal combustion engines. Therefore, established horsepower ratings refer to the power that the engine will produce at its rated rpm under a specific combination of weather conditions.
Corporations internationally have settled on adoption of I.S.O. (International Standards Organization) engine test standards, as set forth in I.S.O. 3046 standardizing the computation of horsepower from data obtained on the dynamometer, correcting all values to the power that the engine will produce at sea level, at 30% relative humidity at 70 deg.F (20 deg.C) temperature and a barometric pressure of 29.61 inches of mercury.
Summer Conditions of high temperature, low barometric pressure and high humidity all combine to reduce the engine power. This, in turn, is reflected in decreased boat speeds–as much as 2 or 3 miles-per-hour (3 or 5 Km per-hour) in some cases. Nothing will regain this speed for the boater, but the coming of cool, dry weather.
In pointing out the practical consequences of weather effects, an engine–running on a hot, humid summer day–may encounter a loss of as much as 14% of the horsepower it would produce on a dry, brisk spring or fall day. The horsepower, that any internal combustion engine produces, depends upon the density of the air that it consumes and, in turn, this density is dependent upon the temperature of the air, its barometric pressure and water vapor (or humidity) content.
Accompanying this weather-inspired loss of power is a second but more subtle loss. At rigging time in early spring, the engine was equipped with a propeller that allowed the engine to turn within its recommended rpm range at full throttle. With the coming of the summer weather and the consequent drop in available horsepower, this propeller will, in effect, become too large. Consequently, the engine operates at less than its recommended rpm.
Due to the horsepower/rpm characteristics of an engine, this will result in further loss of horsepower at the propeller with another decrease in boat speed. This secondary loss, however, can be regained by switching to a smaller pitch propeller that allows the engine to again run at recommended rpm.
For boaters to realize optimum engine performance under changing weather conditions, it is essential that the engine have the proper propeller to allow it to operate at or near the top end of the recommended maximum rpm range at wide-open-throttle with a normal boat load.
Not only does this allow the engine to develop full power, but equally important is the fact that the engine also will be operating in an rpm range that discourages damaging detonation. This, of course, enhances overall reliability and durability of the engine.
Comment
-
Originally posted by cpostis View PostTruman Kid, you boat in Flathead Lake, MT? If so, Beautiful. see the attached image.
Guys, this lake is about 2,900 feet above sea level. What would you have to do to get best performance at this altitude? Is there a certain altitude where changes become necessary?Last edited by boscoe99; 08-03-2016, 09:27 PM.
Comment
-
Originally posted by Truman Kid View PostThe tag on the port side of the engine says " PROV 150G" in the serial # area "304073". I hope that helps.
http://www.boats.net/parts/search/Ya...0LG/parts.html
304073 is the serial number.
Comment
Comment