1981 90 hp outboard won't start

[fishon2]

I have a 1981 90 hp Mercury outboard. When I bought it, it had been left out in the elements for 3 or 4 years. I have had the lower unit serviced and have myself replaced the spark plugs and one switch box which a trusted mechanic told me was faulty. Now the motor will crank but it won't start. I've noticed fuel coming out the front of all 3 carbs as well so I plan to rebuild them next and to replace the impeller. I am fairly good with engine repair but this is my first outboard. I have a repair manual and am getting to know it better. I realize that there could be several things wrong with this motor given the lack of care it has gotten and am looking for suggestions on what else to look for.

 

[hkeiner]

Re: 1981 90 hp outboard won't start

There are lots of possibilities. I think that the first thing to do is use a spark tester to confirm that you have a good spark on all cylinders when cranking the motor. The next thing to try is to squeeze the fuel bulb and/or spray some 50:1 fuel mix into the carb throats to see if the motor responds when cranking. Doing a compression test is also to good basic test.

If you report back on the results of these first few tests, you will likely get advice that more closely fits your problem.

 

[fishon2]

Re: 1981 90 hp outboard won't start

OK. I got a spark on all 6 cylinders. Sparks were visible over about 1/4" gap though I wouldn't say they were particularly strong. Compression ranged between 145 and 155 psi for all 6 cylinders. Squeezing the fuel bulb was no help either.