1973 50hp evinrude suddenly lost power

[walleyewizard]

Hi everyone,
Last fall I bought my 15ft runabout w/ 50hp evinrude. Ran great at low rpm but had no power or speed. Over the winter I removed the carbs and cleaned them and put them back on. I took it out for the first time last month and it ran great, like brand new. Went through 1/2 tank of gas. the next day I refilled the tank and added more oil to make 50:1 mix. I launched the boat and drove across the lake at about 30 mph for about 10 mins then 10mph for 5 mins then back to full speed for 5 mins. All of the sudden the motor slowed right down to like 10 mph. Now im back to square 1, starts and runs great at idle, even runs good in gear at slow speed but when I open up throtle the motor just bogs and will not pick up speed or rpm. I have changed gas tanks and hoses from tank to motor, drained gas and remixed, ran with cover off. Motor runs great in the driveway w/ water hooked up, but on the lake under load no change. What next? Please help theres not much of a fishing season in northern British Columbia Canada, times a wastin! I look forward to reading your ideas on the matter.

 

[wvmedic]

Re: 1973 50hp evinrude suddenly lost power

walleyewizard, did you change the hose and tank after the problem presented it self?

Jeff.

 

[walleyewizard]

Re: 1973 50hp evinrude suddenly lost power

Yes I did, I also just found an in line fuse on the right side of the motor. When I opened it up to check it, the fuse was good but someone has put a piece of tin foil inside the rubber boot where the fuse is supposed to seat. Do you know what this fuse is for?

Mike

 

[wvmedic]

Re: 1973 50hp evinrude suddenly lost power

walleyewizard it is in the ignition system, if it blows the engine won?t crank by the key and the electric choke will not work.

The reason I ask about the fuel line and tank is, if there was any derbies in the tank or bad fuel hose you could have picked up some in the carbs.

Jeff.

 

[kenmyfam]

Re: 1973 50hp evinrude suddenly lost power

Do a compression and spark test. Post results. Could be dirt in fuel system or carbs again.

 

[tashasdaddy]

Re: 1973 50hp evinrude suddenly lost power

agree with ^^ also, could be clogged high speed jet again

Ethanol and fuel lines
replace all fuel line with Alcohol resistant lines. Ethanol deteriorates, the rubber lines, then they start to sluff off on the inside, going directly to the carbs. Settling to the bottom of the bowl. Contaminating the carbs high speed jets. clean a rebuild carbs, flushing fuel line before connecting to carbs.