Welcome to Carver Yachts Owners Forum

We are a boating forum for owners of Carver Yachts to enthusiastically discuss all aspects of Carver Boat ownership. Whether you are looking for your first Carver or currently own one, you are sure to feel at home on CarverYachtOwners.com

You are currently viewing our board as a guest which gives you limited access to view most discussions, articles and access our other FREE features. By joining our free community you will have access to searching the forum topics, post topics, communicate privately with other members (PM), respond to polls, upload your own photos and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

rpm drops at high speed

GAS engine, transmission and generator repair and maintenance discussion forum.
User avatar

Topic author
Scurvy Dog
Scurvy Dog
Posts: 1
Joined: June 10th, 2015, 5:40 pm
Vessel Info: 1987 Carver Riviera 28'

rpm drops at high speed

Postby mhirschhorn » January 31st, 2016, 12:45 pm

I have a1987 Riviera 28 with twin 220hp crusaders. One engine is fine at low rpms, but when advancing the throttle, the revs drop and then go up and down. Checked fuel filter. Rebuilt carbs installed 3 years age because of similar problem, was fine until now. Is the carb bad again or is something else causing the problem?

User avatar

United States of America
CYO Moderator
CYO Moderator
Posts: 2404
Joined: February 5th, 2013, 9:24 pm
Vessel Info: 1995 Boston Whaler Rage15
1987 3697 Carver Mariner
1988 Cougar 46 Kevlar Vee offshore
1969 15' Glasspar / 1967 Johnson Electromatic 85
1996 Boston Whaler Rage 15
Location: Saint Joseph,Mi
Has thanked: 50 times
Been thanked: 395 times

rpm drops at high speed

Postby waybomb » January 31st, 2016, 2:29 pm

You should have a separate spin on filter as well as one mounted at the carb. Make sure use a 5/8 flare-nut wrench for the fuel line nut and a wrench to hold the filter housing still.

Be very careful reinstalling the filter housing - the threads are fine threads and can be stripped easily. Don't forget the gasket for the adapter.
1969 Glaspar Avalon /1969 Johnson Electromatic 85
1987 Carver Mariner
1988 Cougar Kevlar 46' with triple blown 572 ci
1995 Boston Whaler Rage
Past - 1988 2807, 1989 4207 Aft
User avatar

United States of America
Posts: 267
Joined: January 5th, 2016, 10:02 am
Vessel Info: Carver 3227 Sedan Convertible
1986 - 260 Mercruisers - Kohler 5E
Location: Lake Norman, NC
Has thanked: 20 times
Been thanked: 87 times

rpm drops at high speed

Postby SplashyLady » February 1st, 2016, 4:11 pm

Engine surge (not holding RPM) is often a sign of fuel starvation. As said above, check the fuel filter to be sure it's properly seated. Then we need to look at fuel supply.

It could be a fuel pump issue, or sometimes this will happen if the gas tank vent is clogged/plugged. Dirt daubers are famous for getting in the vent line and plugging it up - then the fuel pump can't pull gas out of the tank fast enough to feed the engine. You can check this by simply leaving the fuel filler open and doing a test run - if the engine runs OK - you know the problem. Just get some wire and clean the vent line out.

Fuel pumps are pretty dependable, but check for loose fittings on the suction side - the pump will pull air before it pulls gas, and that can lead to fuel starvation. If you can, put a pressure gauge on the outlet side (between the fuel pump and the carb) and see what pressure your fuel pump is putting out. You should have 4-5 PSI if the pump is working correctly.

Hope this helps - good luck!
Captain John
Past Commodore, Peninsula Yacht Club
Lake Norman, NC
Carver 3227 - "Splashy Lady"
Aquasport 222CCP - "Gone Fission"

Return to “Gas Engines/Transmissions”

Who is online

Users browsing this forum: No registered users and 7 guests