50 hp force wont start

[jeffrobodini]

I have a 1987 force 50 hp model 507x7c. I bought the boat last summer and took it out 2 times. Both with no problems. On the third trip I was throttling up when I heard the motor slow and eventually it stopped. It has not started since that day. I have replaced all fuel lines and filter, cleaned carb and replaced multiple gaskets. Both plugs are getting nice blue spark but motor just won't crank. Today I noticed that when I took the top plug out to test it and left the bottom plug in it started right up but stopped after a few seconds. When I took out the bottom plug to test it and left the top plug in it wouldn't start. I am at the end of my knowledge. Any help would be appreciated.

 

[roscoe]

Re: 50 hp force wont start

Welcome to iboats.


We need to narrow this down so we know where to look.
And need to eliminate some areas.

Ok, you have spark.

Is the fuel getting into both cylinders?

Next up would be a compression test.

Simple to do, $25 tester from auto parts store will do.

 

[wickware]

Re: 50 hp force wont start

1. Have you tried to spray some of your 50:1 fuel mix into the carb while cranking as a primer to see if possibly it?s a fuel issue? This is the system I feel you have not tested good or failed to mention etc..

2. You mention good blue sparks. Even though plugs might not be firing under compression.

3. You mentioned it has fired-up but have you checked the compression in the cylinders? At least feel the compression with your finger or thumb over the plug holes while cranking (if you d/n have a gauge handy). You s/n be able to hold the compression in the cyl in this quick test.

4. Also remember there is a precaution you should use to protect your ignition sys while cranking the eng w/o the plugs in and connected or grounded (as grounding the plug wires or cranking with the starter jumpered with the ign switch off with certain models).

Telling all you know about the engine and all your tests will help toward solving the matter.

Real Help Is On The Way! LOL.

 

[jeffrobodini]

Re: 50 hp force wont start

Thank you for the response. Actually fuel was my original thought and I have done everything to rule that out. New fuel lines, primer, see thru filter, all new clamps,cleaned gas tank in and out,checked tank filter. Yes there is some gas on both plugs. Fuel was coming out the front of carb after failed starts which I hear is normal for these motors. But I did find that the spring in the carb was jammed so I fixed that. Not vommiting gas anymore but still won't crank. When I turn the key the starter engages and spins the flywheel but won't turn over. Like I said it started briefly with top plug out but nothing with any other configuration. I see the pistons moving and feel the compression but will have to get a tester to be sure its in specs.