66 50 hp low speed surging and slow under load

Andy in NY

Andy in NY

Commander
Joined
Oct 25, 2007
Messages
2,109
Okay, so ive been out 3 times since the carb and fuel pump rebuild. i've come to the conclusion that it likes to mess with me...

right after the rebuild, she ran awesome. 27 on gps... no problems idling.

then friday i had her out, took about 3-4 min to get up on plane, but still hit 27mph. then we stopped for something, she was idling great then just died and had a hard time restarting. once restarted ran great.

Both times was with 2 people, about 440lbs between us.

yesterday I was out, and it was fairly windy with some good chop. going into the wind, 8-10 mph at wot. turn the other direction, BAM she takes right off to 25.


then on the way back in, its a no wake zone through the channel for about a mile. the whole way, it was surging pretty noticeably.


why is it that it runs great till you put any kind of load on it?
 
C

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: 66 50 hp low speed surging and slow under load

Idling puts little demand on both the fuel and ignition systems. As load is increased with throttle, then fuel flow increases as well as an increased demand for voltage to fire the ignition system.

Basic troubleshooting makes no assumptions.

Start with a compression test to ensure that the mechanical components of the motor are sound. All cyl relatively even.

Test spark to ensure a healthy hot bright blue CRACK, to ignite the mixture AT IDLE.

A DVA Meter is a great tool to have in your toolbox, use it to test the stator output at cranking. The stator has TWO sets of windings, Low RPM and High RPM. Mirginal output of the High RPM windings can cause acceleration problems and as the insulation on the windings degrade further, the problems get worse.

DO NOT ASSUME ANYTHING, and DO NOT BUY any electrical parts until proven bad as they can get expensive quick and there is NO RETURN on electrical parts.
 
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