E'rude 50hp - fuel, spark, comp but won't start

nstevens · Sep 2, 2003

Hope someone can advise here as I'm confused. Engine - 1978 50hp Evinrude 2 cylinder History - professionally reconditioned in 1992 then used lightly for 4 years. Laid up for 7 years then recomisioned by me this year. New water pump impeller fitted. Started fine and checked over in tank at home. Problem - First time out it died after 5 mins slow running. Started ok again. Did this 4 or 5 times then ran ok for over an hour. Second time out started doing the dying thing again before finally conking out altogether (couldn't restart it). I've spend the last day and a half trying to get it going again and I'm now stumped! When it cracks over it sometimes fires once and this is usually at the point when I stop turning it over. Here are my findings : Petrol - I know this is good as it was a fresh mix and today I used some in my 4hp engine (filled from empty) and that ran for about 20 mins with no problems. Also tried squirting fuel direclty into the carbs whilst turning it over but makes no difference Carburation - Stripped the carbs. No gumming or blockages. Fuel present in both bowls. Choke operates correctly. Fuel pump - stripped and checked. Filter and diaphragm ok. Compression - 140 and 134. Strangely though I checked this a number of times (resetting the guage each time) and had readings as diverse as 50, 62 and 90. Not sure if there is something more to this or whether my guage is faulty. (borrowing another one at the w/e to check this). Plugs - installed new ones with correct gap (0.04"). Checked spark at each plug and no 2 was a bit weak. Swapping components has narrowed this down to the coil. Ignition timing - connected strobe to number 1 plug. Cranked over with throttle back and it shows firing at 2deg BTDC. Full throttle shows 20deg BTDC. I would have thought that with twin cylinders/carbs and coils that it would at least start on one of these sets unless the problem was with a common component e.g. charge coil. Ummmm... You guys have helped me in the past with my 4hp and I really do appreciate the time you spent and effort you make. BTW - I have the Clymer workshop manual for this engine.......

marinegrh · Sep 2, 2003

Re: E'rude 50hp - fuel, spark, comp but won't start

Ummm, charge coils, you are on the right track, you would think the engine would run on one of th 2 cylinders unless............ its a shared component right, I'd start there, Compression is a big thing, and its gotta be right, fire and fuel, all these things go hand and hand, so you at least now have a starting point By the way how were the check valves in the fuel pump? curious to find out whats wrong

nstevens · Sep 4, 2003

Re: E'rude 50hp - fuel, spark, comp but won't start

Check valves looked good. I've done some more tests tonight and one of the secondary coils is definitely playing up so I'll get a replacement tomorrow. I used a Gunson 'colortune' on it and I get a good spark under compression (from the good coil) so I'm fairly sure the rest of the ignition is ok. Tried heating the plugs up with a burner (off the engine!) and refitting them. When I cranked it over it fired intermittently and also back-fired a couple of times. Could this be a reed-valve problem? What are the symptoms of a sticking reed-valve?

marinegrh · Sep 4, 2003

Re: E'rude 50hp - fuel, spark, comp but won't start

reeds usually dont stick, the usually crack and break, thus creating a dinner for your engine, have you done any adjusting to the idle air mixture, these are done 1/8 increments, is this a lean condition due to the mixture, could be, when you get the engine running on both cylinders fine tuning will be next, good luck. keep us infoed

nstevens · Sep 6, 2003

Re: E'rude 50hp - fuel, spark, comp but won't start

Haven't touched the carb settings at all. I checked the compression again with a new tester which gives readings of 160 and 170 (consistently)so I guess the old guage is 'kaputt'. Also fitted a new ignition coil and now have two great sparks but........still the same problem!!!!!!!!! It will fire occasionally but won't start

I'm running out of ideas now so please feel free to suggest anything

Joe Reeves · Sep 6, 2003

Re: E'rude 50hp - fuel, spark, comp but won't start

Legin.... With a engine sitting up for seven (7) years, those carbs should have been fouled. Did you actually remove and clean the fixed brass high speed jet that's located in the bottom center of the float chamber? Fuel must flow through those jets before it can gain access to any other fuel passage. Spark, with the plugs out, should jump a 7/16" gap on all cylinders with a strong blue lightning like flame. Have you or anyone else had the flywheel off? If the flywheel nut is not torqued to exactly 105 foot pounds, the flywheel key will shear which results in having the engine out of time. If the carburetors have adjustable slow speed jets, the adjustment procedure follows: (Carburetor Adjustment - Single S/S Adjustable Needle Valve) Initial setting is: (All Carbs) Slow speed = seat gently, then open 1-1/2 turns. Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting. Repeat the procedure with the next carburetor. When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

nstevens · Sep 6, 2003

Re: E'rude 50hp - fuel, spark, comp but won't start

No I didn't clean that out Joe but a full carb strip will be next. Wouldn't you expect it to run a little if you sprayed fuel direct into the carb though? (I've seen this suggested on other threads) Perhaps you could verify something for me please. I removed the spark plugs and put a plastic straw into no.1 cylinder (I'm assuming that's the top one) to see where the piston was when I moved the flywheel. It is at not at TDC when at max compression...in fact it's nearly 180deg out. Doing the same to no.2 cylinder shows that its TDC is showing at 36deg on the flywheel markings. This seems to fit with your theory about the flywheel woodruff key. However, when I checked the timing with a timing light connected to number 1 HT lead it was showing it firing at 2deg TDC

Appreciate your help and advice.

nstevens · Sep 6, 2003

Re: E'rude 50hp - fuel, spark, comp but won't start

Had another think about why it is showing 2deg TDC if the key had sheared and of course it would as it gets timing from the flywheel. Me being thicker than a whale ommlette

I'm afraid. I'll pull the flywheel off tomorrow and check it out........

nstevens · Sep 7, 2003

Re: E'rude 50hp - fuel, spark, comp but won't start

Well done Joe, your advice was right.....the key was in two causing the flywheel to slip on the crank. You are the oracle. Please accept my thanks. You mentioned tightening the nut back up to 105 ft/lb but my Clymer manual says for 2cyl engines 1973-1977 it is 100-105 (as you say) but for 1978-1984 it should be 80-85. Mine is a 1978 so I guess it should be the latter. The engine had been professionally overhauled about 10 years ago and I'd imagine they'd have had the flywheel off. Maybe they torqued it to 80 and it should have been 105 and that's why it sheared. Is there an easy way of identifying what it should be from the engine i.e. size of nut?

Joe Reeves · Sep 7, 2003

Re: E'rude 50hp - fuel, spark, comp but won't start

I've also noticed that 80-85 foot pound torque recommendation in a couple of the OMC manuals, but I ignore it as a misprint and apply the 105 setting. I do this as the crankshaft threads are the same, the nut size is the same, and the later manuals go back to the previous 105 foot pound setting. An example of what I'd consider a misprint (to pick a year) would pertain to the 1979 manuals. It lists the flywheel nut torque for a 55hp at 80-85 foot pounds, but in that same year a 25hp is listed at 105 foot pounds. That, in my humble opinion is not logical. Note that the straight edge of the flywheel key should be straight up and down with the engine, not with the taper of the crankshaft. I'd torque it to 105.

nstevens · Sep 11, 2003

Re: E'rude 50hp - fuel, spark, comp but won't start

Will do (when I can get a new key out of my local parts supplier

). You Americans like to hang on to your spares! Just a thought though - If I'm holding the flywheel whilst tightning up the nut, would this not be putting 105ft/lb pressure through the woodruff key? Wouldn't this shear it? I can't hold the crank in anyway can I?

nstevens · Sep 20, 2003

Re: E'rude 50hp - fuel, spark, comp but won't start

Installed the new Woodruff key and torqued the nut to 105 ft/lb with no problems. Engine starts and runs fine. Today is a good day......... Thanks for your help with this one Joe.

Guvner.. · Sep 20, 2003

Re: E'rude 50hp - fuel, spark, comp but won't start

I find myself copying, pasting and saving the information I see on here all the time.. Some very smart, knowledgable people... Gary

E'rude 50hp - fuel, spark, comp but won't start

Cadet

Petty Officer 2nd Class

Cadet

Petty Officer 2nd Class

Cadet

Supreme Mariner

Cadet

Cadet

Cadet

Supreme Mariner

Cadet

Cadet

Seaman Apprentice