15 hp johnson won't start

[Carmstrong]

I've got a 15hp Johnson that won't start early 1990's
pull start only
already took carb off and thuroughly cleaned, visually checked all jets
carb sprayed passage ways to verify, etc...
the plastic cam roller that opens the throttle was broken, that was replaced,
took the front part of the fuel pump off, diaphram and all looks fine, etc...
Compression is just over 100 psi each cylinder, checked for spark at each plug
looks good
I've tried priming the motor with carb spray both via the throat of the carb
and by taking the spark plugs off shooting some spray directly into each cylinder
however when I try to pull start it
I get nothing to indicate that it's even trying to start, no kick, no pop,
I do get a bit of what feels like somewhat of a hydralic lock
which I'm figuring is just from the liquid carb spray that I've primed into the motor
wondering if the pull star motors are that tricky to get started?
are there techniques that help
or
what other problem might I have
striped keyway on the flywheel, etc...
I figured if the timing was off at the least it would backfire or do something to show some life
The plugs look clean and ok
but perhaps they could be gas fouled and fooling me

 

[bktheking]

Re: 15 hp johnson won't start

Not usually tricky to start, pull out the choke, pump the fuel bulb hard, set the throttle to start and pull over till it starts.

If you suspect the flywheel key pull the flywheel and inspect.

 

[Carmstrong]

Re: 15 hp johnson won't start

Thanx
I Tried all that

Next I'll give the flywheel key a peek

 

[bktheking]

Re: 15 hp johnson won't start

Very rare to have a broken flywheel key, usually only happens if the flywheel was not torqued properly. Compression is good, you fed motor some sort of starting fluid, it's got spark, all that's left is timing.

 

[Tim Frank]

Re: 15 hp johnson won't start

I've got a 15hp Johnson that won't start early 1990's
pull start only
.....

Is this motor new to you or have you had it a while?
If new, any chance plug leads got crossed?

 

[bktheking]

Re: 15 hp johnson won't start

Yup shoulda thought of that one.

 

[Carmstrong]

Re: 15 hp johnson won't start

The motor is new to me

yes
thought of that too
so I switch the wires and tired them both / either way

 

[AlTn]

Re: 15 hp johnson won't start

sounds like you're headin' in the right direction checkin' the flywheel key..if it's good...I'd verify 7/16" dry gap spark jump on each plug wire with a dry gap spark checker

 

[Carmstrong]

Re: 15 hp johnson won't start

I'll give that a try too
along with some new spark plugs

never used a dry gap spark checker
wondering where I can purchase one
sears?
I guess I could check the local auto parts stores
or how bout using a wide gap spark plug and just opening the gap some more if need be

A mechanic at the local boat shop suggested using a power drill to spin up the motor and see what happens from that
see if I can get some kind of life out of it

 

[Rick.]

Re: 15 hp johnson won't start

I've used a drill but only when my recoil was buggered. It should start pulling the recoil. I agree with the above spark check and flywheel key check. If your not seeing spark you could disconnect the ground from the kill switch just to rule it out. Also when you replaced the roller on the carb. did you do a linc and sync? Best of luck. Rick.

 

[Carmstrong]

Re: 15 hp johnson won't start

going to check out the flywheel key today, a spark test , and then kill switch

can you tell me more about the linc & sync
all I did was overhaul the carb and install the new roller
also I'm wondering what the mixture screw should be set at
I think it was right at 3 1/2 turns out

Thanks

 

[Rick.]

Re: 15 hp johnson won't start

So here is when I tell you to seriously consider buying an original OMC service manual for your specific motor. They are worth there weight in gold to us who do our own motor work. Linc. and sync. is described in there too. Basically you move your throttle until you see the carb. throttle plate just start to move and I mean just move. When it does look at the cam the roller you replaced is rubbing and there should be an indicator mark on the cam that must be dead center on the roller at the point where the throttle plate just starts to move. If it isn't lined up perfectly you adjust the roller until it lines up with the mark. It will take several attempts to get it right. Your slow speed needle should be out 1 1/2 turns from lightly seated as your initial set point. It should run at that and then you adjust it from there with the motor running at idle. Hopefully you'll have it running today. Rick.