TOPIC: Hit a ROCK, 1974 15hp

OHH boy! Ruined my fishing trip. I was motoring along, fairly slow, and didnt see the rock. Hull scraped over, and I lifted the motor as quick as I could but I know the skeg and prop both hit. I didnt think it hit very hard.

So, at the lake the motor will start, but dies when put into gear.

Im not sure what might be damaged. It goes in and out of forward and revers fine while not running. Seems fine anyway. While not running in neutral the prop spins by hand easy, no noise. In gear it locks up(not running), as though its engaging the crank shaft, just like it used to.

At the lake, when started, and put into gear, it bogs down, prop turns a few times, then it dies. So, its engaging while running, both forward and reverse.

Im going to put it on the hose now, and try again now that Im home.

What is the likely damage? I dont see any cracks, splits, or holes. The lower unit was pretty scratched up anyway, and it dosent look any different.

Update: It was hard to start here at home. Was hard to start at lake today also, before hitting the rock. I finally got it to stay running. Cycled through gears, accelerated both forward and revers, seems fine???

I think my slow adjustment is off, because I had to prime the cylinders with a shot of gas to get it to start. Once warmed a little, it stayed running,and I was able to test gears. No noise, just ran out nice and fast. I didnt rev to full throttle just on the hose, probably around 2/3 throttle just to see if it would stay running and spin the prop.

I dunno. Going to goto lake again tomorrow, after work, and see if it runs under load.

Could I have damaged the power head in such a way that it runs on the hose but not with a load?

Is it just a coincidence that fuel issues might have made it seem like a no go after the hit?

I swear it wasnt too hard a hit. Rock was down enough that I scraped over it, but didnt get hung up. I do know the skeg and most likely the prop hit.

Close examination of the lower unit reveals no cracks and no leaks.

?????

Wow. It seems like a bizarre coincidence but if there's nothing still going wrong with the gears I'd have to vote for a fuel issue ? Sounds like something moved a little, then moved back maybe ? I'd wait for Ed or another Guru for a pro opinion though. Tossing a coin won't cut it. Good luck with it Afterthought, when you and the rock both lifted the motor quickly, do you think it might have just drained your float bowl ? I know some bikes have an overflow for that situation (if they tip over or a float gets stuck) but whether or not that happens with outboards is for someone far wiser than I to say. Did you have to prime it again at home to get it started ?

I was thinking that it souned like you may have bent the drive shaft. but if you did,nt shere the pin in the propeller sow your probably ok. but I think that you may have stured up the gunk in the bottom of your carb bowl. let us know how you come out on this. Bob

Maybe the prop got banged and the rubber hub is warped. Then when you put it in gear the thrust of the prop is binding on the driveshaft/gearcase. A way to check this would be to pull the prop and inspect the rubber hub.

I will pull the prop today, and put a micrometer on the shaft if possible. No gunk in the carb bowl, Its freshly rebuilt as of about 4 runs ago, all clean gas too.

What should I look for on the rubber hub? Obvious deformation?

The carb has a vent hole at the top of the bowl area. That hole opens into the carb air intake silencer. Its possible that tipping up the motor drained the gas in the bowl into the air intake silencer, allowing the motor to start a couple times, but not run more than a few seconds.

Im hoping that is the case. Going to the lake today and see if it runs under load.

Good luck. Hopefully it just needed to burp. lol.

Unfortunately this little motor isnt running very well lately. Dont know if I messed up the ignition timing,, dont think it can get messed up other than points setting.

I went back up the mountain to the same lake, cold day,, and almost didnt get it started at all. Once I did get started, it ran on only 1 cylinder. Im amazed it even started,, and kept running after put in gear.

On the flip side,, fish were biting steady,, fly fishing with spinning gear, and using a clear float,, knocking em dead! Black and grey mosquitoes just left to float were producing excellent results.

Got home, pulled plugs, top plug completely fouled, bottom plug partly fouled.

Cleaned plugs, and she started on second pull, ran out fast as can be,, on the hose,, in warm weather.

At the lake about 2000 feet higher, and cold weather,, it dosent want to run. Fouls the plugs before it will even start.

I guess, Ill pull the flywheel, and reset the points.

Very possibly just sheared the woodruff key on the flywheel.

Nah, I took it off, its good. Thats a good point though. I just realized from your suggestion that that could also throw off timing,, really drastically.

Im thinking of possibly running a bh5s plug on top, and a bh6s on bottom.

Top plug is sometimes a bit just a bit looser than bottom when I go to check them.

I think its an altitude issue? At home it starts easy and runs fine on the hose. At a high mountain lake yesterday it was hard to start, but did get going(clean plugs) but ran out only half arse. Was obviously over loaded, because it was audibly fouling the plugs as I ran for the dock.

We ran out the trolling battery in the middle of the lake, so the evinrude 15 was our last resort! If it hadnt started, we would be rowing, against the wind.

Anyway, started up, ran in gear, I would say about 2/3 power? Couldnt get up on plane, but made a big wake behind. I could hear it getting rougher, slightly missing more and more as we ran. When I reduced throttle, it would run smoothe for a bit then start missing again, so I would throttle up again to try and keep the plugs clean so we could get home.

Funny thing is close to the dock, I had it idled all the way down and it kept running. I expected it to die as soon as I bottomed out the throttle, as it was running like crap IMO. It stayed idling till I killed it on purpose.

At home on the hose again, started up easy, ran out the gas in the carb
and reved out like a kids dirt bike fast and loud.

So, I think altitude and plugs??

Ive only had it running at a lower altitude lake once, and it ran out fast, planed my 12 foot boat easy. That was a couple months ago. Ever sinse running at higher altitude, its been a dog.

Wondering if changing to the 9.9 carb would help at altitude?

What about changing the main jet from the 15 main jet to the 9.9 main jet but keep the 15 carb?

I have both and they are slightly different in both the hole diameter, and the length of the jet itself. Would it run too lean with the 15 carb and 9.9 main jet?

I did a little linc and sync today. It was pretty close, so I tried to get it a little closer?? Before it was ever so slightly off, with the carb opening just a bit after the mark. It was close. Now its fudged the other way slightly, with the carb lever moving a tiny bit, but the tension of the linkage being felt right at the mark, so I think the carb might get about a couple degrees more open at WOT. Its all so close and minute though,, might not make a lick of difference.

Goin to lake again to test,, if I must!

link and sync didnt make any difference. So, I pulled flywheel again, and re did the points. They seem to be settling in a bit tight. I didnt measure where they were at, but it was tighter than .020.

I read a bunch of stuff regarding setting points using a multimeter, and timing marks on the flywheel, rather than setting at the"set" mark on the cam.

I dont know how much of a difference that would make, but it surely isnt very possible for the shade tree mechanic without the timing arm tool. Or, without drilling a hole in the fly wheel to access the points with the flywheel in place. According to that article, its a crap shoot to set the points mechanically.

Top plug gap was a bit tighter than .030 as well, so I opened up both plugs to allow a no interference fit of the gap gauge. Im sure thats about .033 - .036 ish

Ran on the hose again, and pulled the plugs after. Plugs came out nice and clean,, a definite improvement,, on the hose anyway.

Today at the lake was a disaster,,, nothing but troubles, wasted time, wasted gas, wasted money...Too many big fast boats making big waves,, not a good day for testing at all, and the few minutes I did run were only conclusive that theres something really off with the tune.

Im pretty sure the fuel system is aok. So far its been an issue of very quickly fouling the top plug, even when starting with clean plugs and running at full throttle. It has been getting worse the longer it runs,, to the point it will only run on bottom cylinder,, and thats just barely.

Hoping to test again soon. The re do on points and plug gaps seemed to make a noticeable difference in sound, and plug cleanliness.

Thought..check the quality of the spark? Might be weak. Check the condition of the plug wires. Check float level in the carb? Sounds like it might be running rich?

One thought from left field, possibly a cracked reed valve?

Also might be time for a compression check....