Repeating Power Loss on 1988 Classic 50 45hp

WICKER55

Seaman Apprentice
Joined
Aug 24, 2019
Messages
36
I’ve been working on this old boy for a while after buying it 6 months ago and after a short but very successful Test run I took it north fishing. The first outing my friend and I (about 200 lbs. each) were intending about a ten mile trip up the lake. The boat took a while to come up on plane and we were off. Climbing to 5500 rpm and 25 mph in my Tracker Deep V 16ft at full throttle, I was happy. After 15 minutes I was thrilled then the engine sound change and the rpms dropped fairly quickly to about 3800 and the boat came down from plane and speed dropped to 7.5 mph still at WOT. I turned around and reduced the throttle until mph started to drop and we limped back to our camp. The next morning after checking to see if the fuel tank was vented and no spark plug wire had vibrated off the plug we took it out for a test run trying to figure out what happened the day before and behold although the motor seemed a little rough running for a second it took off and we were on plane in no time, then the same thing as yesterday (5500 rpms, 25 mph at WOT) and probably around the same time period (12-15 minutes) it happens again. Had to finish the fishing week close to the camp. After I got home I checked the coils, following YouTube instruction and using a digital ohm meter I got basically the same results as the video (00.3 between positive and negative on the 200 settIng and 968 between the outlet to the plug and each of the primary points on the 2000 setting).
Anybody got any suggestion where I goto next in my quest to get this motor running? I always appreciate the help.
 

WICKER55

Seaman Apprentice
Joined
Aug 24, 2019
Messages
36
Oh, and while I was disconnecting wires from #2 cylinder to check the ohms on the coil I noticed there was an extra wire attached to the ground on coil. I followed extra wire back to a long black plastic box that doesn’t look like original equipment because it’s just hanging supported by a tie wrap. Out of the other end of this hanging box is a blue wire and a blue and white wire which go to top and bottom screw of the right side of the switch box. Also I pulled the plugs and #2 cylinder plug was quite fooled. All guidance appreciated.
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
38,579
Did you install a new water pump impeller ?-----Post the results of a compression test here.
 

WICKER55

Seaman Apprentice
Joined
Aug 24, 2019
Messages
36
New water pump was installed, tell tale always has a good stream of water. I’ll have to see if I can find the gear for a compression test.
 
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