bad head gasket?

I'm working on a mid 70's Johnsn 9.9 that won't start. I'm getting strong spark, after cleaning and regapping the points. It's getting fuel. I tried starting it, even with a socket on the flywheel, but I'm not getting it to fire. I tried it with starting fluid, and even then, it might sputter for just a split second but still won't start. The compression is at 80 psi on each cylinder, which is pretty low. Does this sound like it could be the problem, and how do I identify a bad head gasket as opposed to a more ominous cause? Thx in advance.

Re: bad head gasket?

rope start motor, 80 psi in fine. how do you know it is getting fuel. read ethanol here,
http://forums.iboats.com/showthread.php?t=299680

DO NOT USE STARTER SPRAY, best way to burn a hole in a piston. use premixed fuel in a spray bottle.

Re: bad head gasket?

I said this was a 9.9, and that's misstated. 9.5, and sorry about that.
I don't think that the problem is with ethanol. I'm familiar with that. I'm working on this for someone else, but I always use my own pre-mix. I have fuel going from the fuel filter to the carb. I pulled the line to check. I tried both pre-mix and starting fluid in the plug holes and in the carb, and I can't get any serious fire with anything I'm doing. The spark seems decent on both plugs, and the points are freshly cleaned. It probably needs a new set of plugs, but my feeling is that the problem goes beyond that. Any other suggestions?

Re: bad head gasket?

Sheared flywheel key? That would change the timing. You would still have spark, just at the wrong time before compression occurs.

Re: bad head gasket?

Any chance that you have switched the plug leads?

Re: bad head gasket?

It should still fire up, if you have spark and compression it can only be one of 2 things, your timing is off hence Evinrude Boaters suggestion of a sheared key which you would have hopefully noticed when the flywheel was pulled or you didn't torque the flywheel bolt down enough on reassembly and have since sheared the key. I have a 65 9.5 and it can be a little tempermental to start but it always does. Set it to start, pull the choke, squeeze the primer bulb till first and give it 4 or 5 pulls. The other thing to check is the idle circuit, if you had the carb apart and put back together did you adjust the idle screw properly. It should still run by feeding it premix gas through the carb.

Re: bad head gasket?

All of these look like pretty good suggestions. It's not a sheared flywheel key. I didn't take the carb all the way apart. Just pulled the fuel lines to check for the presence of fuel, and I have it. The timing may be off, which is going to cause me serious grief because I don't know the first thing about it.
I think I'm going to tear the carb apart tonight and work on that. Thank you guys for the suggestions. I'll post an update when I finish with the carb.

Re: bad head gasket?

How did you confirm the flywheel key isn't sheared? You have to take the flywheel off to see it properly.

Re: bad head gasket?

Tim Frank said:

Any chance that you have switched the plug leads?

Click to expand...

This would be the same as a sheared key.