1979 EVINRUDE 70 SLOWS AFTER RAN

[CWAYNEK]

I purchased a 1979 Ski Boat with a 1979 Evinrude 70 hp on it. First, the motor cranks but only after several attempts. It takes a several turns of the key to get the starter to engage but it turns over everytime after the motor warms. Secondly, after running for about 30 minutes or so, it slows down as if you cut the throttle back and continues to slow the longer you run it. Can anyone help me with these two problems? Thanks for your help?

 

[BoatBuoy]

Re: 1979 EVINRUDE 70 SLOWS AFTER RAN

First problem could be:<br />- dirty electrical connections<br />- bad solenoid<br />- weak battery<br />- starter draging<br />See http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=36;t=000001 <br />Sounds kinda like battery is weak. After running a while, it is temporarily charged and starts OK.<br /><br />Second problem could be:<br />- fuel tank needs venting<br />- motor overheating and seizing due to insufficient cooling or fuel mix<br />- maybe other things I haven't thought of<br /><br />I assume you've checked the throttle linkage to make sure it's not throttling itself back.

 

[djzyla1980]

Re: 1979 EVINRUDE 70 SLOWS AFTER RAN

I think you have a Impellor goin bad. Check the electrical as BoatBouy said... If all checks out... Check the Impellor.. Heck if you just bought it I would check it anyways and replace so you know it's done. <br /><br />Just went through this today... Would run with some water comming from my installed peehole... but would slow down when gave it throttle. If I idled it was fine... but anything above that the heat warning lamp would kick on.. Pulled off LU tonight and found Impellor only had two fins left... the others were just floatin around in there.

 

[CWAYNEK]

Re: 1979 EVINRUDE 70 SLOWS AFTER RAN

Originally posted by BoatBuoy:<br /> First problem could be:<br />- dirty electrical connections<br />- bad solenoid<br />- weak battery<br />- starter draging<br />See http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=36;t=000001 <br />Sounds kinda like battery is weak. After running a while, it is temporarily charged and starts OK.<br /><br />Second problem could be:<br />- fuel tank needs venting<br />- motor overheating and seizing due to insufficient cooling or fuel mix<br />- maybe other things I haven't thought of<br /><br />I assume you've checked the throttle linkage to make sure it's not throttling itself back.

 

[CWAYNEK]

Re: 1979 EVINRUDE 70 SLOWS AFTER RAN

Thanks. I'm replacing the battery today to insure I'll get the full cranking amps. After that I replace the soleniod.<br /><br />I've checked the venting of the fuel tank, fuel mix is at 50:1 as required. I'll check the impellor next.

 

[CWAYNEK]

Re: 1979 EVINRUDE 70 SLOWS AFTER RAN

Thanks. I'm getting water coming out the pee hole but maybe not the amount that should be flowing. I'll change the impellor and hopefully that will slove this problem. I'll reply again to let you know if the problem is corrected.

 

[Silvertip]

Re: 1979 EVINRUDE 70 SLOWS AFTER RAN

If what you've done has not solved the problem, if the engine continues to bog, squeeze the primer bulb a time or two. If the engine picks up its time for a fuel pump rebuild or installation of a new one. Batteries can be load tested so don't dash out to buy a battery unless you know its bad. Check the alternator output at the battery using a cheap voltmeter (or the one on the dash if you have one). If it shows 13 - 15 volts at anything above 2000 rpm its working.