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1987 Force 15hp Model 152F7A occasionally fires and won't stay running??

WyattYoung7

New member
Hey guys, I acquired an '87 Force 15hp outboard awhile back that wasn't running. I did all the normal maintenance including: new spark plugs, cleaned the carb, checked compression (it was normal and even), and also checked the reed valves which seemed to be mostly closed but I decided to flip them just in case but had the the same results as before flipping them. I am getting spark and gas to the plug, but it will only occasionally "pop" when trying to start it. It has tried to run for a second after the "pop" a few times. Where do I need to start now? Crankshaft seals??? Completely new reeds???

Thanks!
 
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Check the spark?
What I do, I remove the plugs, hook up 2 spark testers and turn the motor over( I use a drill with a socket)
That way the motor turns with no resistance and the spark is easier to see as the motor turns over.
That also shows if there is intermittent spark????

The reeds: can be completely closed or with a small gap.

Carb setting: turn the air screw in(gently) till it stops and then turn out 1 1/8th turn.
That's the initial setting. Adjust after it starts.

IF?? you've been trying to start a long time?? the fuel oil builds up in the cylinder and will be hard to start.
A quick shot of starting fluid might help. Not a lot, it can wipe the protective oil from the cyl.

Look on U-tube for videos about setting the carb.
 
UPDATE: I spent today adjusting the mixture screw on different settings and found 1.5 turns out to be a fairly decent spot which gave me more times of trying to fire. Attempting to start the first few tries resulted in the usual "pop", so I then applied a little starting fluid which resulted in starting and running for maybe 2-3 seconds a few times. I then came up with the idea that the fuel is getting to the plugs somewhat but not a steady flow. Checked the fuel pump and it was working perfectly. Then I took the carb off to see if there was any blockage and did a quick cleaning that blew some stuff out but not a whole lot. Stuck the carb back on, and after about two seconds of cranking and a little starting fluid, it fired up and ran for about 4-5 seconds. It fired and ran for 2-3 seconds a few other times after this. My first assumption is that I'm getting trash in the carb from the very old gas tank I am using. My next step is to thoroughly clean the carb and put on an in-line filter to see if this solves the problem.
 
The float might be stuck?
The bolt/screw that holds the float bowl on might have some holes that gets clogged.
Make sure they are clear.
 
UPDATE 2: I installed the in-line fuel filter today and tried to start it up with no luck. I checked for spark from both the plugs, and there is no spark from either one now. What the heck did I do to cause this?
 
I put new plugs on thinking I fouled the others last night. Still no spark after putting new plugs on.
It is point ignition and the model # is 152F7A
 
UPDATE 3: I found out that my on/off switch had shorted out which kept me from getting spark, so I fixed that. After fixing that, I had another guy come over and try to help me get it running with no luck. We have finally decided that there must be leaks in the crankshaft seals letting air in which isn't allowing the proper amount of air flow through the carb to bring in fuel. When you place your fingers in front of the carb while cranking, there is only a light suction happening. I checked compression and it was even and normal again. So now I will replace the crankshaft seals if I can find somewhere that sells them. Any body else have any other explanations of what is happening?
 
Did you clean the jets in the carb?

The vacuum or draw isn't that much on your motor.
Hook up something to add air to your carb or blow into the reeds and see if there is an air leak at the seals?
Very rare that the seals go bad???
Even if the seal was bad the motor should run, run bad but should run.

An air leak or sucking air: the motor will backfire, stutter, cough, run rough.
 
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