1975 50 hp dies at full throttle

[elpasomedic]

This has happened twice now. I'm running full/almost full throttle and the engine quits (1st time about 20 mins into it, last time approx. 1 hr into my run). The last time, I needed to be towed back to the marina. I didn't want to start anymore (the starter would turn with the turn of the key). The following day, I tried it just for kicks at home, and the sucker fired right up. I replaced the spark plugs prior to the last incident, am running in fresh water. Anybody???

 

[steamboatwilly]

Re: 1975 50 hp dies at full throttle

Did you put oil in the gas.

 

[Joe Reeves]

Re: 1975 50 hp dies at full throttle

Check the fuel primer bulb to see if there's anything laying within the bulb. The inner portion of the outlet valve (the one where fuel leaves the bulb) has been known to come apart, fall in the bulb, then at some point become drawen back into the valve body.... but it will always be drawn in backwards. The inner valve portion being backwards shuts the fuel off completely.<br /><br />Compression.... what is it?<br /><br />Spark .... should jump a 7/16" gap with a strong blue lightning like flame.... a real SNAP! Does it?<br /><br />The stator under the flywheel..... is there any portion of it where a sticky substance is dripping down on the timer base and block? If so, that will cause a voltage drop to the powerpack. When the engine is cold, even with a stator melting down, the ignition may be fine, but when hot, the votage output from the stator to the powerpack will drop. Thsi results in erratic igniton.... and eventually no ignition.

 

[MCM]

Re: 1975 50 hp dies at full throttle

Welcome elpasomedic, I have the same motor and just went through some ign. system problems of my own so if I can help from time to time I will.<br /><br />Joe's definately got the experience with these motors and definately one to listen to though.<br /><br />Good Luck

 

[elpasomedic]

Re: 1975 50 hp dies at full throttle

Yes, there is oil in the gas, I will check the bulb, discharge, and spark. I will see you soon.

 

[elpasomedic]

Re: 1975 50 hp dies at full throttle

Joe and everyone else,<br /><br />The compression is 100 psi on both cylinders, there is a strong lightning like spark, and there is no sticky substance leaking from the stator. The gasoline bulb is intact. The engine is now working, but I don't know if it will happen again, this last time was the second time the engine quit suddenly, without warning and wouldn't start. Anybody Please Help.

 

[MCM]

Re: 1975 50 hp dies at full throttle

Have you got a service manual, preferably OEM? also a volt/ohm meter? <br /><br />As I said earlier I just went through this, the scenario was a little bit different, but the same sometimes it starts sometimes it doesn't.<br /><br />Compression looks ok, sounds like the coils are ok,<br /><br />I suspect it may be difficult to troubleshoot until it acts up again, the problem is probably going to be in the ign. switch, the power pack, or the timer base which is ultimately where my problem was.<br /><br />To check the timer base (sensor): <br />a: Disconnect the sensor leads (white w/black stripe & black w/white stripe) from the power pack, with the ohm meter set to LO ohms scale connect the meter to the sensor leads, the meter should read 15.0 +/- 5.0 at room temp.<br /><br />b: Now set meter to a HI ohms scale, connect meter to either sensor lead and ground. Zero reading indicates leads or sensor coil are grounded.<br /><br />You may want to check the readings now and again later if or when it acts up again.<br /><br />Its a place to start