1994 Johnson 48 SPL - Ran great, now crank no spark

[Crashsector]

Hi all -

Trying to make a long story short. We ran our restored 16.5 ft. MFG runabout yesterday for the first time since taking ownership. It has a well maintained but lightly used 94 Johnson SPL.

The engine had brand new (same day) fuel/oil. First start in the driveway was clean, very little smoke, and it idled fine.

Against my advice, my friend decided to go WOT after passing the no-wake buoys and left it there for the better part of 30-40 minutes. The engine ran great - no hiccups, did about 25-30mph with 5 guys in the boat. After the third time throttling back to take some wakes the motor started stumbling. After shutting it off we realized we ran the fuel tank dry.

After switching to the second tank, also with brand new fuel/oil, the engine would crank but would not start. We were towed back in and we got it to fire once, it idled for about 30 seconds and then died.

It is getting fuel as it pushes fuel out without a plug in while cranking and there is a slight slick in the water pump outlet. We don't think it's getting a spark since we didn't see one when holding the plug near the block, but it was very bright out.

Any advice where to start? I hate throwing parts at a problem, but I think that's what we'll do, starting with the coil pack.

Any help is appreciated. My background is electric bass boats and my friend's is four stroke inboards. Tow stroke outboards are a mystery.

Thanks in advance!

--Andy Juskelis
Arnold, MD

 

[fireman57]

Re: 1994 Johnson 48 SPL - Ran great, now crank no spark

Get a 10.00 spark tester from autozone and test your spark.

 

[Crashsector]

Re: 1994 Johnson 48 SPL - Ran great, now crank no spark

Get a 10.00 spark tester from autozone and test your spark.

Thanks, I'll give that a try after work today.

What would be the appropriate next steps if I do or do not have spark?

Thanks again!

--Andy Juskelis

 

[fireman57]

Re: 1994 Johnson 48 SPL - Ran great, now crank no spark

If you are missing spark to one cylinder physically swap the coils and see if the problem follows. If it does just replace that coil.

 

[Crashsector]

Re: 1994 Johnson 48 SPL - Ran great, now crank no spark

Thanks for the help. We had a chance to troubleshoot a little further today.

Spark is actually fine. Today as precaution we replaced the plugs, fuel tank, fuel lines, fuel, oil, and installed an in-line fuel filter.

We can get the motor to start and idle in forward and reverse. We can give it up to about 1/3 throttle just fine and it will run all day. As soon as we move past that, the motor dies very quickly.

The motor is then very hard to restart. We usually have to unplug the fuel line and dry crank it for 20-30 seconds until it tries to catch, then reconnect the fuel line and it will start.

One thing we did today was after it died and while we were cranking the engine we removed and then replaced the safety clip. As soon as the clip is reinserted the motor turns over. It will still do just fine until about 1/3-1/2 throttle, then it cuts out again.

Any help with this is appreciated. I feel a little better that we've narrowed down the troubleshooting a bit.

--Andy

 

[Crashsector]

Re: 1994 Johnson 48 SPL - Ran great, now crank no spark

I forgot to mention... tied up to a dock it will go to full throttle no problem. It's only when it's out on the water that it cuts out over about 1/2 throttle.

Thanks for any help!

--Andy

 

[fireman57]

Re: 1994 Johnson 48 SPL - Ran great, now crank no spark

Sounds like the carbs need a good cleaning. You may have a high speed jet clogged. Soak them overnight if you can in a good cleaner and blow everything out with compressed air.

 

[Crashsector]

Re: 1994 Johnson 48 SPL - Ran great, now crank no spark

Gave up and took it to an outboard mechanic today. Culprit was a bad ground to the coil. The motor got a perfect (like new) bill of health and I'm happy to report it now runs like a stabbed rat.

Thanks!

--Andy