1975 Evinrude 50 won't start Help!!

[trogsie]

I recently bought a 14 foot Savage with a Evinrude 50573b 50hp 1975. It sounded good and started first kick with the muffs and hose. Took it out and didn't get much speed about 20kmh tops (Sorry I'm an Aussie) about 12mph. Anyway in neutral I pulled up the throttle lever to show my bro it had plenty of rpm and I said maybe it's the prop slipping? or the pitch? too low? Regardless when we took off it stalled and would NOT start. Only backfiring every 20 seconds. We embarrassingly got towed in by some nice blokes and gave them a few beers as thanks. When I got back I tried to start it , still just backfiring loudly ever 20 seconds of cranking. Checked the grounds, all seemed good. Changed the sparkplugs to new NGKs (Nothing) Checked coils, bottom ones High Tention lead just fell out of it when i wiggled it and even though I was getting spark when i put them back in I decided to buy new coils, not expensive and couldn't hurt even if it was something else. Replaced coils still just intermittent loud back fire , just every 20 seconds or so, like it was fluking timing? I dunno, I'm very new to this caper. Went through the trouble shoot in the manual with a multi meter a best as I could but it asks me to use a neon light meter to check the power pack. I figure it could be the Power pack maybe? I'm hoping it's not the Charge coil or sensor coil because I believe I'd have to replace timer base or stator as well if that's the case. I don't have a neon S-80 or M-80 light tester as they suggest in the manual? I hear they haven't been used for years! Can anyone suggest how I test the power pack without a light tester? Just a multimeter? I'm going to do the trigger coil input check tomorrow with a spark tester I made and a 1.5volt battery hooked up to 6 and 7 on the power pack and then reverse it the sensor coil high ohm check which says it should be 750-75ohms . In the meantime, can anyone suggest the reason this just happened out of the blue? I'm a novice and one of you guys might know exactly what it means , Going then stall and not even kicking over. It could even be a fuel or carby thing? I dunno? , I checked the compression and it was up at around 145psi on both , which I thought was extremely good for such an old engine. So that's obviously not the problem. All help muchly appreciated!. Cheers, Ash

 

[trogsie]

Also, I checked the compression and it was up at around 145psi on both , which I thought was extremely good for such an old engine. So that's obviously not the problem.

 

[racerone]

Check the flywheel key.

 

[trogsie]

Cheers Racerone, I'll do that.

 

[trogsie]

Check the flywheel key.

Hey Racerone , I'd just like to thank you a second time nearly 5 years later I just rebuilt the engine and was pretty bloody impressed with myself tbh , I'll post some pics . Anyway after dotting every i and crossing every t . New gaskets, piston rings, sparks , electrics checked , carby kits fitted with new needles, new starter motor , nice new coat of high temp paint, new impeller, gear oil etc , I checked compression and was getting almost 150psi on each cylinder give or take 1 or 2 , which was factory spec I believe. I went ahead and set the idle timing with light and digital tacho and the thing sounded absolutely CRACKING!!! EXCITED, I openned up the throttle and put it in gear with the muffs on and gave it a tiny bit of throttle . Sounded amazing then..... Bang pop ! Bang pop! Fark !! What I done!!!! ??? Depressed for a day I went back to this forum and was about to ask for some advice and saw this post from 2017 in my haste I'd not torqued the flywheel down very hard cause it's a pain in the arse and forgot that I'd told myself "I'll just set the idle timing because it's not going to be spinning very quickly , and I'll talk it down properly before I open it up" after so many hrs being maticulous , I got excited and forgot!! So accidentally stumbling across the only thread I've ever posted , I saw your answer to the same question! I went straight downstairs feeling very optimistic and when I had to use a puller to get the flywheel off which I'd cleaned and greased the hell of ! I realised you'd saved me for a second time!! Off it popped to reveal a flywheel key completely broken . The flywheel is fine. I'd just had it so loose it slipped then half of it disintegrated . So I just wanted to thank you again!!! For saving me twice!!! New woodruff key !! FW torqued down and it sounds amazing!!!! Cheers Ash

 

[trogsie]

Hey Racerone , I'd just like to thank you a second time nearly 5 years later I just rebuilt the engine and was pretty bloody impressed with myself tbh , I'll post some pics . Anyway after dotting every i and crossing every t . New gaskets, piston rings, sparks , electrics checked , carby kits fitted with new needles, new starter motor , nice new coat of high temp paint, new impeller, gear oil etc , I checked compression and was getting almost 150psi on each cylinder give or take 1 or 2 , which was factory spec I believe. I went ahead and set the idle timing with light and digital tacho and the thing sounded absolutely CRACKING!!! EXCITED, I openned up the throttle and put it in gear with the muffs on and gave it a tiny bit of throttle . Sounded amazing then..... Bang pop ! Bang pop! Fark !! What I done!!!! ??? Depressed for a day I went back to this forum and was about to ask for some advice and saw this post from 2017 in my haste I'd not torqued the flywheel down very hard cause it's a pain in the arse and forgot that I'd told myself "I'll just set the idle timing because it's not going to be spinning very quickly , and I'll talk it down properly before I open it up" after so many hrs being maticulous , I got excited and forgot!! So accidentally stumbling across the only thread I've ever posted , I saw your answer to the same question! I went straight downstairs feeling very optimistic and when I had to use a puller to get the flywheel off which I'd cleaned and greased the hell of ! I realised you'd saved me for a second time!! Off it popped to reveal a flywheel key completely broken . The flywheel is fine. I'd just had it so loose it slipped then half of it disintegrated . So I just wanted to thank you again!!! For saving me twice!!! New woodruff key !! FW torqued down and it sounds amazing!!!! Cheers Ash

 

[trogsie]

After before!

 

[trogsie]

FW key

 

[racerone]

DO not put any grease on the tapers.----Assemble clean and dry !!!

 

[tphoyt]

Great story
Glad everything worked out for you

 

[ejnichol]

Good News!