I have a 100 hp Evinrude the last time I ran it it died and I have yet to be able to resart it. Changed outthe plugs, pulled te carbs cleaned them, put new hoses on and still all it will do is backfire every now and then. I have checked the spark and it seems to have spark t the plugs. I am stumped. Does anyone have any ideas on what I can do next? :'(

i have an 75 evinrude on my LIL flat bottom that done this..... i blowed it up by keepin on tryin to mess with it but go take it an have ur COMPRASSION checked an see if its right cause if it ant u will blow it up 4 sure.... an is your boat oil injected or do u mix ur gas an oil yourself???? an have u checked ur water pump lately mayb u ran it HOTT an messed up ur heads???? its a thousand things it could b sounds like LOL but wish u best of luck on fixin it....

She's still pumping water and I mix the oil myself. Guess I just need to take the hit in the wallet and take it to a professional.  :'(  

do u think u messed up mixin it this time by to much GAS???? if thats true u BURNT it up an that ant good but if u put to much oil then u need to get a GOOD carb cleaner but 1 more thing  i would suggest u do is go to ur local  EVINRUDE/JOHNSON place an pick  up some cans of EVINRUDE/JOHNSON motor power tuner or engine tuner  an mercury has some of this to an its called power tuner it just cleans out ur carb's realy good an tune's ur jets i would realy look in to tryin that b4 i spent alot of money on letin some 1 check it.....

I started out having a problem with Idle, she had good top end but, when I would try to idle or switch direction it would die. I mixed all of the gas at 50 to 1 ratio and on the last tank I added a half a can of sea foam to a full 12 gallons of fuel. It has always had a slight amount of smoke which tells me that oil is present in the mix. The mix is getting to the plugs because when I try to start it they get flooded. and with the front cover off the carbs I can see it coming out when I get off the choke. I have checked the plugs out of the motor and am getting spark in all four. I puled both carbs and cleaned but they were already impeccably clean.

Only takes a few basic things to make a motor run.  Good spark at the right time, proper fuel air/fuel mixture and compression.   If one of these is off, she's not gonna run or run properly.

First varify the spark with a spark checker set to a 7/16" gap.  If it can give a good blue spark over a 7/16" gap, you don't have good fire.

Next connect a timing light to number one and make sure it's firing at the proper time.  With the throttle fully against the idle stop, it should be zero to minus six degrees.  If way off, you may have spun a flywheel.  Then check the other three cylinders and make sure they are firing at the proper time.  You may have to mark the flywheel for three and four.

If all that is good, then you have fuel/air problems or compression.

Have you tried spraying gas in the carbs to see if it will fire.  If you have it did nothing, you probably have spark problems.

Remember one thing also, the motor has to spin at over 250 rpm or it may not generate enough spark to fire properly.  Weak battery or dragging starter can cause it to spin slow.

Thanks way2 slow. You nailed it them flywheel was spun. got a new key and I'm back in business.

I wondered about timiing but didn't know enough about marine engines to tell. reminded me of a car I had once that the timing belt had broken.

BR.om comes through shining once again thanks to its members!

It's the greatest I spent .34 cents and fixed it myself when I could have spent hundreds and the dealer. Thanks so much. Got back on the water today and caught me one of these "little fish".