1972 Johnson 85 running rough

[carmangary1]

My 1972 Johnson 85 started running really bad yesterday. Here is a history of what happened:<br /><br />1. Last time I had it out 2 wks ago it ran great. 5500 RPMs on choppy water. Had a problem where there was a loose connection in wiring harness.<br /><br />2. Boat sat 2 weeks outside in Texas heat (covered with tarp).<br /><br />3. Replaced wiring harness. While replacing it, I noticed that blue 2-cycle oil was dribbling out of powerhead area. Not sure why it was so oily (could gasoline evaporated and left oil only?)<br /><br />4. Took boat to lake. Hard to start and sounded like it wasn't running on all cylinders. Finally, got and it running and it sounded better.<br /><br />5. On lake, it seemed to lack some power and would only get to 5000rpms on a smooth lake. It kept getting progressively worse until it wouldn't idle anymore and very hard to get started. It would fire a couple times and then stop.<br /><br />6. Afterwards, if I started the engine and immediately gave it some throttle, it would run but it was obviously not running on all cylinders anymore. Now and then missing cylinder would kick in and it would have a surge of power. Sometimes it would stay running on all cylinders for a long several seconds. Sometimes it would only kick in for less than a second.<br /><br />I tried squeezing the primer bulb and that didn't help. I tried choking the engine while running but it didn't do anything. Someone told me to try that to see what happens but I don't know why.<br /><br />I am thinking it is either an ignition problem or clogged carbs. I have had this exact problem on this boat several times but haven't figured out exactly what the problem is. Usually, I rebuild the carbs, change plugs, and reset the points and then it runs OK. I'd like to narrow it down to the actually cause so that I don't have to keep repeating myself!<br /><br />Also, should there be a fuel filter somewhere? <br /><br />Thanks<br />Gary

 

[carmangary1]

Re: 1972 Johnson 85 running rough

Any ideas what could be wrong or what I should check first?

 

[carmangary1]

Re: 1972 Johnson 85 running rough

One more try. Any helpers? Thanks.

 

[Joe Reeves]

Re: 1972 Johnson 85 running rough

Before attempting anything, regardless of the problem, always start with the basics.<br /><br />Check compression... should be approx 100+ psi and even on all cyls.<br /><br />Check spark... (with plugs out) should jump a 1/4" gap on that model on all cyls with a strong blue lightning like flame.<br /><br />Always a good idea to check the points. Check that gap on all lobes as some set at slightly different gaps. Better to have the gaps set to something like .010 and .012 rather than say .010 and .008 (it happens). You can't just set the gap on one lobe and assume the other lobe is identical.<br /><br />If the above check out okay, do a general cleaning of the s/plugs, and check to see that the timer base isn't sticking when you advance the throttle or has a frayed or broken wire somewhere.<br /><br />If the engine has been sitting for quite some time, the possibility exists that they are somewhat clogged. Remove the 7/16" hex bolt from the lower side of the float chambers. If the back of those bolts are gummed, discolored, etc, they are more than likely fouled and will require cleaning.

 

[carmangary1]

Re: 1972 Johnson 85 running rough

Thanks Joe. <br /><br />While I am messing with the points, how much oil should be on the wick that touches the cam?<br /><br />Gary

 

[Joe Reeves]

Re: 1972 Johnson 85 running rough

Two or three drops should be enough, just enough to see that it's moist.