Where to start????

[Thumper2442]

I bought a 15 hp Johnson a couple weeks ago before we went to the lake. It ran super for a few days, then suddenly it died going across the lake a WOT. After it cooled I put it on the tail gate and pulled a plug to check for spark. When I barely pulled the rope it started on one cylinder. Put it back on the boat and it ran fine about 150 yards and died again. Sounds like electronics to me but I've not had the flywheel off one without points. Where do I start troubleshooting it???
Thanks a bunch.

 

[iwombat]

Re: Where to start????

Sounds more like it overheated and stopped. What year is it? How long did you run it dry? Could have toasted the impeller.

 

[Thumper2442]

Re: Where to start????

It's a 1982. I only ran it a few seconds on the tailgate. I really did not expect it to start. I'm glad it was in neutral. The second time it died I pulled the hood to check the power pack and it was only warm. I guess I should have pulled a plug then but it definitely acts like it simply looses fire.

 

[iwombat]

Re: Where to start????

How's the water stream - good? When was the last impeller change?

 

[iwombat]

Re: Where to start????

Also, did you try pumping the bulb to keep it going?

 

[Thumper2442]

Re: Where to start????

The stream is good and it was not hot any time I checked it. I checked it often while it was running good. I have a 1974 15 hp Johnson that overheated the first time out. That cost me several days and a lot of money replacing rings and other stuff. Since then I keep a close eye on the water temp. I bought this motor the day before we left so I didn't get to look at the impeller. Just kept and eye on the water regularly.

 

[Thumper2442]

Re: Where to start????

Both times it died I made sure it was getting fuel and cranked it several times. It would not start but once it cooled then it started on one cylinder.

 

[iwombat]

Re: Where to start????

Well, first off - spark check and compression test. Let's make sure you're not beating a dead horse.

Check the coil grounds, clean them up and dress the block with a file where the grounds make contact. Same for the power pack. Check your kill switch leads and make sure they're in decent shape. Run it for awhile in a barrel and see if you can get it to fail again.

 

[Thumper2442]

Re: Where to start????

I'll try that and get back with you. Thanks a lot for the help. I can work on mechanical things but troubleshooting is my weakness.

 

[Thumper2442]

Re: Where to start????

Ran it in a barrel for quite a while and it wouldn't die. I'm assuming running under a load will cause a little more heat and cause it to quite firing. If that is the case.......where would a guy start troubleshooting this problem? I'll run it on a lake again in a day or two to make sure that is the case. It starts too easy and runs too good for it to be an internal problem.

 

[Thumper2442]

Re: Where to start????

I ran the motor on a small lake this evening and it died after going about 200 yards. I pulled a plug and as I suspected, it didn't have any spark. I brought it home and it has had time to cool but still won't start. Tried to pull the flywheel to look for any visible problems but didn't have the right bolts for that flywheel. What is the next step? When I do get under the flywheel what do I look for?

The last motor I worked on I ended up with twice as much in it as it is worth without paying any labor. The wife is wondering when I'm going to spend some money on her. I'm glad she likes to fish.....technically I am spending money on her.

 

[iwombat]

Re: Where to start????

The next thing you can do is try and heat up some suspected components while running in the barrel. A hair dryer can do the trick nicely. I'm gonna bet on the power-pack. Try heating it up with the hair dryer for 5-10 minutes while running and see if you can reproduce.

 

[Thumper2442]

Re: Where to start????

That makes a lot of sense. I hope to try that this evening. Again, thanks for the help.

 

[Thumper2442]

Re: Where to start????

I took time to test the power pack this morning. After a couple minutes with the hair dryer on it the motor lost fire again. Thanks a bunch for the help. Parts are so expensive, I hate to pay labor also.

 

[iwombat]

Re: Where to start????

Sounds like you found your culprit.

 

[rudedude]

Re: Where to start????

I was going to say the coils were going out on you. I had a 4hp and a 6hp that started doing the same thing. Each time it would take longer to start and less time to shut down, I replaced the coils for around 30 bucks each and never had a problem after that.

 

[iwombat]

Re: Where to start????

Before you go out and buy a power pack you should try running it again w/o the heat on the PP. If it stays running, you'll really really know. Could be that the problem is just getting worse. Probably not, but still a possibility.