1983 Evinrude 9.9 wont fire

So heres the story. Bought this motor for $100 and I was told it had sat for 3 years. When I got it home I was going to check for spark and found it had a stripped spark plug hole on the lower cylinder. Did a quick spark check and had spark so with the help of my son did a compression check (had to hold the tester by hand on bottom cylinder) I had 92 and 91# so went ahead and pulled the head and had a helicoil put in. Replaced the head with new gasket and put back together. While I was waiting for the head to get done and my gasket to come I went ahead and replaced the waterpump and cleaned the carb. I replaced the fuel lines with new while I had it apart. Okay, so today I go to fire it up and it wont fire?? I again checked for spark and it would span a 3/8 inch gap with a spark tester. Carb bowl was filing with fuel but the plugs looked dry. I didn't pull the little plates on the carb just soaked it overnight in a can of carb cleaner. Cleaned it all up and sprayed it out with compressed air and the aerosol carb cleaner. Next, thinking something was plugged still on that carb I took a old 15hp carb that I had saved from a old motor that was clean and tried that. No luck. Still no fire in the cylinders BUT I have spark. Did another compression test-91 and 92 again. The plugs are new but seem dry. I have cleaned a lot of them 9.9 and 15 hp carbs and never had to pull them little plugs before but maybe that's whats causing it to not get fuel to the cylinders? Fresh fuel and oil mix in a tank I had just mixed and used so not a old fuel problem. I would think it would get some fuel to fire even if something was still plugged. Would bad leaf valves cause this? Sorry for this being so long but tried to explain all I have done so far. Thanks for any help, Jim

When you replaced the head, did you make sure that the plug wires went to the correct plug? #1 to the top plug?

Get a spray bottle and put a bit of mixed fuel in it. Give the carb throat a couple of sprays and then pull it over to see if it kicks.

90 lbs is a bit on the low side for those motors, they typically run in the 120's so you might have to pull it pretty hard to get it to fire.

Okay, I have no idea what happened. I took a spray bottle of mixed fuel and after removing the air box sprayed a bit in the throat of the carb. Nothing. Tried it again and still nothing. Took a plug out and it did look a bit wet so I hooked up my spark tester again and I still have good spark? Tried spraying the mix in the carb again and pulled it over 3 or 4 times and thought it fired. sprayed a bit more in and it started running. I didn't have it in water so quickly shut it off and took it to my barrel of water. Hooked up the fuel line and primed it and it took off. Its been running for 10 minutes and all is fine as it fires right off. Did a few carb adjustments and runs great but I do have to pump the bulb every few minutes. Not sure if I have a fuel line leaking or need to rebuild the fuel pump but at least it runs now. Thanks for the suggestion! Jim

Once you get it running feed it a seafoam cocktail and maybe you can bring those compression numbers up a little. 90 is on the low end of what you want (although fine) but would be nice to see a little compression bump.

FWIW on stored motors, I always pull a plug and pour just a little fuel/mix into the cylinder ... fires right up!

The choke lever was ok and fully closing Pappy. All was good there. I buy these older 9.9 and 15 hp motors and try and give them new life so usually I will take and give the cylinders a shot of storage oil before I even try and turn them over so they aren't dry after sitting a few years. We are lucky up here as to get premium fuel with no ethanal but I still give all tanks a shot of seafoam WMK. Not sure what did it but it is running fine now. I have 3 of them now sitting in the garage ready for boats LOL Just a hobby for me. Thanks for all the help, Jim

nytebyte said:

The choke lever was ok and fully closing Pappy. All was good there. I buy these older 9.9 and 15 hp motors and try and give them new life so usually I will take and give the cylinders a shot of storage oil before I even try and turn them over so they aren't dry after sitting a few years. We are lucky up here as to get premium fuel with no ethanal but I still give all tanks a shot of seafoam WMK. Not sure what did it but it is running fine now. I have 3 of them now sitting in the garage ready for boats LOL Just a hobby for me. Thanks for all the help, Jim

Click to expand...

I meant the method of adding almost a whole can of Seafoam to like 1/2 to 3/4 gallon of gas. I have done this on a few older 9.9/15 OMCs and every one of them came up about 10psi.

wmk0002 said:

I meant the method of adding almost a whole can of Seafoam to like 1/2 to 3/4 gallon of gas. I have done this on a few older 9.9/15 OMCs and every one of them came up about 10psi.

Click to expand...

Here is the 'Dunk' method of using Seafoam on OB motors:

https://www.forum.tinboats.net/viewtopic.php?f=4&t=39239

Read the ENTIRE post and note Pappy's suggestion to add extra oil to this decarb mix. I've been using the Dunk method on everything from lawn mowers, to gas weed trimmers, to snowblowers, pressure washers, chainsaws and my old Ford Exploder (Explorer) that was a boatyard hauling truck. Of course on 4-strokes you use it differently.

However, I was GIVEN the chainsaw and $400 pressure washer as 'junk', as they wouldn't start & run. Fillings the carbs/fuel line circuits w/ Seafoam and a good soak for a few days, then treating the engine (4-strokes) as per the can't instructions ... and these items are working well for me!

I'm a firm advocate of Seafoam!