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75 evinrude 9.9hp wony rev out

T

Tattoomike

Member
So I got this matter several years ago as a Father's Day present and it ran awesome until last year the next time I took it out it just did not want to rev out idled find mid-range seemed okay but it would never go about over half throttle

This year I went through it rebuilt the carburetor very well I might add I also replaced all fuel lines and fuel pump new fuel hose and primer and tank and filters and all that

I check the spark and the thing will throw a loud crackling spark over half inch away from the block from the plug and the wires are in good condition the coils I'll be old have plenty of heat coming from them quite spectacular spark I might add and also my linkage cam to the throttle seems to be pretty close as far as adjustment.

But even though it idles fine and gets up to about maybe half throttle slightly less and I've checked the butterfly opens completely 100% but it just seems like it's running really rich and oddly enough it acted exactly the same last year when the problem started but the carburetor was completely clogged up with rust and varnish and the fuel pump didn't work full of rust fuel lines were cracked and all that so I figured doing all the stuff that I did had to fix it but it did not it didn't make a difference at all

So considering I have a new carburetor and new fuel pump and delivery system that is checked and working all well I can only wonder what's causing what seems like a rich condition because when I pulled the spark plugs they were soaking wet with gasoline

I'm getting very frustrated with this motor because I've had it for 4 years and I've had the boat about 15 years and this is like the sixth time it's ever been on the water because I could never afford a motor and I went and wasted all this money apparently for nothing and it's such a hard thing to load even though it's a 12 foot flat bottom I don't have a trailer so I have to pick it up and drag it into the back of a minivan and then pick up the motor and carry it to the boat and put it on and blah blah blah

What would cause this low output at Full Throttle and wet plugs?

By the way this is my first post here
 
Realistically even after having such an incredible hot Spark I kind of wonder if it's the points were timing and I have absolutely no idea how to do that and I highly doubt I have the tools to do that and I definitely don't have the money to let somebody work for $100 an hour on it
 
One more thing when this problem started the boat ran absolutely phenomenal and then the next day it didn't and I've not been able to figure this problem out

It will scream like a stuck pig out of the water... Under load is when it won't rev
 
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Has anybody ever told you the 1974-76 9.9 & 15hp motors were notorious for fouling spark plugs? I saw brand new motors that wouldn't run one weekend. You didn't say you replaced them. If you did, replace them again.
 
fdrgator said:
Has anybody ever told you the 1974-76 9.9 & 15hp motors were notorious for fouling spark plugs? I saw brand new motors that wouldn't run one weekend. You didn't say you replaced them. If you did, replace them again.
Click to expand...

I did not replace the plugs... But I cleaned them well...
I did also hear that I shouldn't use champion in my motor.... Ngk was everyone's favorite.
Anything else while I'm at it?
The plugs arced to the block from 1/2 inch but never tested the gap...
But I have to go 1.5 hrs to the lake and back and single handedly load and unload the thing.... Gets quite painful
 
Have you checked compression of the cylinders?
If you do not have a tester, you can usually borrow one for free from your local autoparts store with a deposit.

Looks like you've checked spark, but the best way to check is with a spark gap tester like a Lisle 50850 (they're only a few bucks from your local autoparts store). Spark should be able to jump a 5/16" gap with a nice blue CRISP spark.

Get a new set of NGK BR6HS plugs (as others have recommended), ensure properly gapped to .030. These plugs run a little hotter than the spec'd Champion plugs and foul less (I have a '76 15hp and have had much better luck with these plugs).

You mention you've cleaned the carburetor.
Have you removed welch plug (nickel sized plug on the top of the carburetor) and made sure that bowl is cleaned?
After cleaning your carb did you reset your low speed needle correctly?

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: 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.

When you did a link-and-sync, your throttle linkage should move exactly when your cam follower is at the mark on the throttle cam. Attaching a zip tie to the throttle shaft can assist with visually confirming this.

Was it pumping water when you were running it last?
It is possible you encountered an overheat condition last time running without realizing it.
 
Mike... I suspect that in cleaning the carburetor, you've overlooked the brass high speed jet that is located way in back of the drain screw/bolt. That jet is removable (1/4x20 threads) but can be damaged easily so be careful with the screwdriver. Your explanation of the problem indicates that the jet (over the years) has finally clogged, fouled, gummed up.

Clean the jet carefully with a piece of single strand steel wire as solvent just doesn't do that job properly. After which, when running for the first time after repairs, adjust the slow speed needle valve as "JohnnyGuy" (above) has listed.

The special tool used for removing/installing jets can be made from any screwdriver that has a shank that just clears the 1/4x20 threads of the drain screw/bolt of the carburetor... cut the end off and file it to resemble the below picture which would be a perfect fit for any of the jets. Click on pic to enlarge.
317002_CARB-JET_REM-INST.JPG 317002 is the tool part number. Ignore the list/sell info, that's long gone. However it should still be available via this site or any dealership.
 
Thanks for some advice from y'all.

1 I used a OMC rebuild kit on the carb.
The SS needle was set afterwards and I have it dialed in.

And as for the main jet I didn't want to damage it and couldn't get it out of the carb but it was poked and prodded with fine wire and solvent and a ton of compressed air..... But it's like it has too much fuel.

2 yes I did the welch plug... Ultra clean as well as everything else.

3 it feels like it has high compression but never got a tester..
I do assume that has good compression though as if you are not holding on well and you don't pull hard and quick the motor will throw you over the back of the boat when you try to pull start it.


4 as for linking in syncing... It doesn't have any way to adjust the roller to the Mark on the Cam... 76 is when the adjust plate of the carb arm was added.... But it was very close.

The last time I ran it and it ran good was last season and then my landlord came up and stole gas out of my gas can and even though I never ran the fuel because he left it open the next time I put a new gas can on it and took it out it would never rev out and everything appears to be in good order but it's very annoying that I put so much money and time into it so far and the problem is exactly the same
 
Also it will fire up with 1 pull on choke... Then 1 pull off choke....
It ran for hours... Just no top end

I wish I had a known good carb to test run to rule out the carb at least.
I wanted to convert it to 15 carb but even used dead carbs going on eBay and Amazon were 200$ or more
 
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You can link and sync the motor. On 74-76 models the cam itself is the adjustment. If you look under the cam you will see 2 small screws loosen those and the cam moves. Replace the plugs with ngk plugs.
 
Can you post a picture of the screws and when you sync them up
Do you go from a complete closed throttle or from where the idle speed is set?
And can you adjust with the flywheel on?
 
Note----on those 9.9 models there is no drain screw that hides the high speed jet.------Float bowl needs to be taken off to find that.-----Sounds like this motor is running on one cylinder.-----Inspect reed valves.---------Do a compression test.
 
I had a thought about what somebody was saying about spark plugs fouling when I check the spark plugs and I clean them I would hold the spark plugs away from the Block 1/2 inch and pull the motor over and they would Arc to the block really good blue hot Spark however when I drowned out the side of the plug to the block to see the ark between the electrode and the little curved thing whatever you want to call it that hangs over to the electric one plug does fire Hot & Blue the other one doesn't fire it all I'd switch them around on the different coils as well and it's one plug that's dead so it very well may be a spark plug only issue so I'm going to go and grab some NGK br6hs plugs and give it another go before I start tearing apart things to check timing and linkage sinking and all that stuff
 
racerone said:
Note----on those 9.9 models there is no drain screw that hides the high speed jet.------Float bowl needs to be taken off to find that.-----Sounds like this motor is running on one cylinder.-----Inspect reed valves.---------Do a compression test.
Click to expand...

Whoops... the high speed jet thing, sorry about that. I just got wrapped up with something else, thinking about a different hp, something! Appreciate the feedback racer.

Your reminder causes me to remember something about the 9.9 & 15hp models... If the slow speed NV was screwed in a little too far, they would definitely drop a cylinder more-so than encounter the normal spitting back lean scenario.
 
It's possible for the insulator on a spark plug to break down.At tickover the spark will be ample,but under load it will not be.
For the price of a couple of plugs,it's worth the expense and confidence that they are working.
 
Well I have replaced everything that don't require removing the flywheel...
All new and OMC only parts....
I'll say this.... If all this is all just a bad plug.... I'm going too tattoo a sparkplug on my self.... I'm not kidding.... I'm a tattoo artist... What's a lil more ink?

I can't believe how I completely forgot about replacing them...
Either way... If it works or not I should have done it
 
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It might be a good idea to pull the flywheel to clean and gap the breaker points.----Does spark jump a gap of 3/8" on both leads now , yes or no ?
 
Just another check or two you can make.Check your HT wire for melted areas.
Also,check the vent in your fuel tank cap.A simple check is to run with the cap undone.
There is a fuel cut off pin in the carb,controlled by the float,if it sticks,the bowl won't fill fully.
They are things that I would check.
I have a feeling your problem is a simple one.
 
Damn.. So if you guys can find a good template for a spark plug.... I'll ink it in...
Put new ngk plugs in the engine and it screams now... Those champion ones are only a half season old....
Running awesome now
 
I am however going to change out the fuel fitting types because I keep knocking them loose with my leg because of the way my fuel tank sets and I stalled out in the middle of the lake because my fuel line popped off the gas tank so I need to find something that doesn't have that stupid little latch to get pressed down while I'm running but otherwise it's never run so good


All that's left now is for me 2 service the lower gearbox oil and trim the motor and the weight distribution in the boat for most efficient plane
 
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I have seven outboards,I use motor cycle click in non return connectors on every fuel pipe.
There is a short length of pipe on each tank.
My main engine is a Johnson,and my emergency engine is a Yamaha.The two engine connectors are different,but I can use any tank on any engine because the connectors on the pipes match.The connectors auto cut off when you break the connection.They are use on racing motorcycles.
 
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