'68 Evinrude 100 HP Starflite

[aquasprot]

I've got some problems with a 68 rude starflite and was hoping someone could help me out:<br />One night the other week, was running back in from a fishing trip, and the boat sort of lurched forward. The motor sounded fine, ie it didn't miss or rev up, but it felt like someone threw the boat into nuetral and then back to 3/4 throttle again. The problem recurred a couple more times and I brought the boat off plane and cruised in with no more problems. <br />Mentioned the situation to a friend of mine, who suggested I may have broken the rubber sleeve inside the prop, and that was slipping. Got that replaced and headed back out for another day of fishing. Boat ran great to the fishing grounds and idled well while we were fishing, but on the way in the same problem recurred. Shortly after I revved up onto plane, the slipping/missing occured. Once it occurs, it only occurs more frequently until you take the boat off plane. <br /><br />So here's the summary: <br />1. The motor sounds great 4/5s of the fishing trip. <br />2. After it's hot, there is some slip or miss that causes the boat to slow down for an instant before catching back on again.<br />3. the problem does not seem to be completely torque related (as my ignorant self would have thought). It would seem much more logical to me if the slip occured every time I put a lot of pressure on the motor, not just after it's been running for several hours.<br />4. the problem does not get worse over successive trips, just over the same duration each trip.<br />5. the engine fast idles fine even when the problem has occured recently.<br /><br />Any help would be much appreciated.<br />thanks<br />ed

 

[Yepblaze]

Re: '68 Evinrude 100 HP Starflite

Could be something as simple as a loose plug wire.

 

[JB]

Re: '68 Evinrude 100 HP Starflite

Ahoy, Aquasprot.<br />Your prop could be ventilating or cavitating. Next time it happens try trimminmg your lower end in a bit.<br /><br />Red sky at night. . .<br />JB

 

[Ted the Rookie]

Re: '68 Evinrude 100 HP Starflite

Went through the same thing with a 67 100 Starflite. It was the selectric shift solonoids in the lower unit-they weren't cheap, either, as I recall. Your problem sounds identical to the problem I had though...

 

[aquasprot]

Re: '68 Evinrude 100 HP Starflite

Thanks all for the help. <br />I'll try all the suggestions, but think it's going to be something along the lines of what ted mentioned. I have already checked the plug wires, and the prop is brand new. <br /><br />For the first two I can definitely work on myself, <br />Ted: how involved was working with the solenoids that you mentioned was the problem? Is it the sort of thing a beginner mechanic could do if he was patient and eager to learn? Also, did yours only act up when hot? Any additional info you could provide would be a help.<br /><br />Again, thanks to you all.<br />ed

 

[iofish]

Re: '68 Evinrude 100 HP Starflite

I am new at this too, however I would give what JB said serious consideration before you start tearing it apart. I have read a bit about water presure differences around the prop and it is tricky stuff. The temperature detail seems important too. Did this new Prop ever work well? Maybe the prop is slipping when everything warms up and gets more viscous or loose. Sellenoids can stick (warp) when they get hot, but should not pop in and out unless they have an internal wire problem. Basicly a selenoid is a piston like thing that is pulled in with an electro magnetic. Poor quality ones have have plastic as in insulator between the wire coil and piston. The plastic can warp when hot. Like I said I know nothing about boats only technology in general.