70HP Evinrude dies after 15 minutes

[jessie]

I have a 15 year lold 70 HP Evinrude powering a 24' pontoon boat. It starts and runs flawlessly. However, after about ten to fifteen minutes at full throttle the motor dies. I checked the fuel and the ignition system and discovered no spark as the cause for the failure. The engine is not overheating. If I let it sit for a while it will start again and run at speeds for about 10 minutes and then die again. Any idea what may be going on.<br /><br />thanks

 

[JB]

Re: 70HP Evinrude dies after 15 minutes

Hi, Jessie.<br /><br />I suspect that you have a "hot short" in the powerpak. When it gets warm enough it just quits. Let it cool and it works.<br /><br />This can be tested with a hair dryer. Take the bonnet off and run the engine at idle in neutral. Heat the powerpak with the hair dryer. If it quits when the pak is hot, let it cool and try it again.<br /><br />If that is not your problem you may have a plugged vent to your fuel tank, When the engine is trying to die after 15 minutes under load, pump your primer bulb and see if it picks up, then loosen the fuel cap and listen for a "whoosh".<br /><br />Good luck.<br /><br />Red sky at night. . .<br />JB

 

[Backlash]

Re: 70HP Evinrude dies after 15 minutes

Hey Jessie,<br />If you're not getting ANY spark I'd suspect the power pack is failing after heating up. JB Cornwell talked about using a blow dryer to try to isolate heat related electrical problems awhile back (see "1977 75hp Evinrude" posted Aug 15, 2001). Check it out. <br />Backlash

 

[Backlash]

Re: 70HP Evinrude dies after 15 minutes

Sorry JB.......I must've been typing at the same time you were. <br />Backlash

 

[JB]

Re: 70HP Evinrude dies after 15 minutes

No worries, Backlash. Been there, done that, got the "T" shirt. I'll probably do it again. . . maybe to you!<br /><br />Red sky at night. . .<br />JB

 

[jessie]

Re: 70HP Evinrude dies after 15 minutes

Thanks, I had considered the powerpack. I tried the reverse of the test you recommended. I turned a can of liquid duster upside down and tried to cool the powerpak after the engine stopped. It did not revive the spark. I think it might be better to use the hairdryer. I'll let you know how it works.<br /><br />Thanks again.<br /><br />Jessie