1986 Mercury 9.8 110 outboard

[Kissdude]

The recoil is taken off right now and will be able to figure that one out.
The motor. I put the flywheel nut on just to turn it and there is no kickback or anything but the pistons move up and down. Pistons look really oily. Is this maybe a bad ring problem?

 

[jimmbo]

Well the Block has a Transfer Port Cover on the Starboard side of the Block that can be taken off, and you can inspect the Rings, and determine if they have Spring Tension, if not, they are either Broke, or stuck. You can also see if the Piston has any Scoring

 

[Kissdude]

The piston rings are what give you compression correct? And if they’re bad could be why no compression. Would oily walls have anything to do with it?

 

[jimmbo]

Oily walls would likely indicate that Gas and Oil were getting into the Crankcase, or someone had poured a bunch of Oil into the Cylinders. If they are broken, or stuck either of those would make them unable to seal. However, a badly scored Cylinder Wall could also do the same

You say it was sitting for a long Time, how long have you owned it?

 

[racerone]

Oily walls is a good sign.----Just repair the recoil.-----Take compression test.----Stop overthinking.

 

[Kissdude]

The Recoil: Either the Spring has snapped, or something has jammed it, preventing it to retract. A bit of Troubleshooting needed. A Word of Warning, if the Spring is not Broken, it will be storing a lot of Energy, and can be VERY Dangerous to work on.
The Link I provided in Post #6, will take you to a Menu, an Exploded view of the Recoil is in there
The Motor: Are the Plugs installed, Properly(Seated with Gasket, not Cross Threaded)? A Compression Test is still needed. Not easy right now, and if I recall, there is no Provision for a knotted Rope to be used when the Recoil is out of commission. Don't even think of using a Drill to spin the Crankshaft, as that may overtighten the Flywheel Nut, and ruin the Flywheel

I got this motor all put back together and still have no wet spark plugs. I've checked the spark and its good but the motor still won't even try to start. I have sprayed a little premix into the carb throat as well, any I deas to what I'm doing wrong?

 

[Kissdude]

Oily walls is a good sign.----Just repair the recoil.-----Take compression test.----Stop overthinking.

I got the motor all put back together, compression is just under 100 on both cylinder. have checked spark which is good and sprayed a little pre mix into carb throat, still won't even try to start. Any ideas?

 

[Mc Tool]

Nobody has mentioned spark timing. Have you got the plug leads on the right cylinders ....try swapping them over and see if it fires .

 

[Kissdude]

I have tried that and nothing. The wires that go on coils I’m not sure about. I’m wondering if the blue/ white stripe wire is positive or negative that goes on the coil.

 

[Mc Tool]

As per post #11 ,have you put premix in the spark plug hole ? It should fire ...give it a few pulls , if it doesnt squirt a bit more premix in and swap the plug leads over and give it a few more pulls ...throttle set about ½ open ....and put only about 1ml ....½ teaspoon in when you prime the cylinders .

 

[jimmbo]

have checked spark which is good

Good? Spark at the plug at Atmospheric Pressure means nothing. Can it jump a gap of 3/8"?

 

[Kissdude]

I might have the coil wires on wrong. I will figure that out and check

 

[Mc Tool]

I might have the coil wires on wrong. I will figure that out and check

Yeah , 100ish psi comp aint brilliant but its enough , decent ⅜" spark, at the right time ,and bit of juice in the plug ole and it should pop off.

 

[Kissdude]

Thanks I will let you know how I make out.

 

[Kissdude]

I have good gap on spark plugs, put fuel down plug holes and nothing happens, doesn't even fire at all. Anything else that I could be missing here?

 

[racerone]

If it does not bark with fuel in plug holes , you do not have STRONG spark or spark at the right time.----Flywheel key sheared ?

 

[Kissdude]

no the flywheel key is ok.

 

[Mc Tool]

You may have a good gap on the plugs and see a spark while grounding plug outside the motor but its a lot harder for a plug to spark inside the motor because ,all being well its needing to spark whilst the air inside the motor in under the 100psi compression you have , so to get some indication if the spark is strong enough to spark under compression it needs to be able to jump a ⅜ inch gap outside the motor not under compression . I know it sounds dodgy but its true.
Logically if you have a good spark , a bit of fuel in the combustion chamber ( which is why we put a wee bit in the plug hole so we can be absolutely sure there is some in there) and compression ( which you have at about 100psi ) it should at least fire ...it may even run for a second or so . If it doesnt fire the most likely reason is that the spark is happening at the wrong time . You may be able to see a spark at the plug but with out a timing light you cant verify that is happening at the right time ....which is why I suggested swapping the plug leads over from top cylinder to the bottom and vice versa . When one piston is up the other is down and the spark needs to happen in the cylinder when the piston is at the top and being that your motor has 2 cylinders that are 180⁰ apart its possible with the plug leads on the wrong cylinders that the spark is happening when the pistons are at the bottom . You could have enough spark to kill an elephant but if its happening when the piston is at the bottom of the cylinder ( no compression ) the engine just will not fire .

 

[Kissdude]

I have tried what you said to do, swapped the plug leads and fuel in the plug holes and still nothing happens when I pull start. I am using a plug tester and it does jump 3/8" on both. Do you think maybe the coils could be bad?

 

[Mc Tool]

I have tried what you said to do, swapped the plug leads and fuel in the plug holes and still nothing happens when I pull start. I am using a plug tester and it does jump 3/8" on both. Do you think maybe the coils could be bad?

No , not if you have ⅜ inch of spark . Its just about got to be ignition timing .
Now would be a good time to google
"1986 mercury 9.8hp ignition timing video" ( it may also include the 7.5hp but the procedure is the same ). There are a few and as they say a picture is worth a thousand words ...or a video . You should be also looking for instructions on how to "link and sync" the timing/throttle adjustments ....and if you havnt already a pdf of the workshop manual is worth its weight in gold .