90hp outboard died suddenly, wouldn't restart

[l008com]

Part 2 of my adventure, the actual problem . . .
So I went for my first boat ride of the season today. I have a 1989 Mercury 90hp 3 cylinder, 2-stroke outboard. It can be a little tough to get started at first, but once its running, its very reliable. Thats my assessment going all the way back to the early 90s. This was our family boat when I was a kid and it's always been reliable.

So today I filled up the tank and headed out. As anticipated, it was hard to start. Mainly I had to rev it a bit to keep it running which means it stalls out when i go back to idle so I can actually put it in gear. So I played that game for a while and eventually was able to get it to say running in gear. This engine is a screamer so once you get it running, it goes from sad to happy very fast.

So I'm heading down the river and a few minutes (2 miles) later, it abruptly cuts out. Very strange. But it started right back up again. Then a minute later, the same thing. Then a 3rd time.

After that, it would not start. The gas tank was filled with brand new gas. The battery was cranking great after the 2 mile 'charge'. Everything was there but it just would not start. I unplugged and re-seated both ends of the fuel line but no change in behavior, it just would not start.

It sure seems like a fuel issue. But this engine has 3 carbs. So even if one got clogged, the other two would still work, and the engine would just run very poorly, right?

So does that mean theres a clog somewhere else in the fuel system? The fact that it happened so abruptly seems like a relevant clue. It wasn't sputtering or slowing. It was just running great, then off.

Any ideas where to go?

Also check for my comment below, I'll link to the fun story of how I had to rescue the boat when all of this happened

 

[Nordin]

You have to check for spark at all three plugs.
I sounds like there is no spark.
If the stator goes bad you will loose spark at all plugs.

 

[racerone]

???----When / if one carburetor is plugged you might be starving one cylinder of fuel and OIL !---Serious damage mat occur.--These motors in good condition start right up.-----Load tested the battery?-----Pushing the key in and holding it in while cranking it over for cold starting ?-----Oil injection tested ?----Water pump impeller replaced evert 5 years?----Post actual results of a compression test.

 

[l008com]

Here's a link to the full story, a non-technical post just about the craziness of recovering my boat after it died:

Boat Died on the Charles River (Massachusetts) - Had to Self Rescue!

I wanted to tell all the details of this crazy night I just had, separate from trying to figure out what is actually wrong with the motor, and how to fix it. So I made a separate post for the actual repair. This post is just for the story! My boat is a 15' Thundercraft bowrider with a Mercury...

forums.iboats.com

 

[l008com]

You have to check for spark at all three plugs.
I sounds like there is no spark.
If the stator goes bad you will loose spark at all plugs.

Well I guess this is where I'll start.

So if I am getting good spark on all three plugs, what does that mean?

If I am getting no spark on all three plugs, do I have to do something else to diagnose the stator or does that pretty much identify the problem at that point? How far in the motor do you have to dig to replace the stator if it does end up being that? Do you just pop off the flywheel and its right there? Or is it going to be more work than that?

 

[Nordin]

The engine need three things to run.
1. Air/fuel mixture (right amount mixture)
2. Compression
3. Spark (at the right time)
Troubleshoot these three, start with check for spark which is easy.
Pull all three plugs, ground them and have the HT wires connected.
Turn the key to start and check for spark at the plugs.
To check for good enough spark you have to check if it can jump at least 3/8 in (10 mm) or more.
To do that you need a adjustable spark tester.
If you have spark then check for fuel, if no spark but fuel delivery the plugs should be wet when you pull them after some starting attempt.
If you have spark and fuel then you have to check the compression in all three cylinders.
To do that you need a compression tester.
But right now start to check spark and fuel delivery and go from there.

 

[tpenfield]

My first guess would be no spark rather than no fuel. A motor of that vintage (age) is likely to have some brittle/corroded wiring. . . BTDT. I would check for spark (a good healthy spark) and go from there.

It also sounds like the motor/engine could use a heavy dose of fuel system cleaner . . . then maybe the idle would be better.

 

[cyclops222]

OLD... any boat motor..... CAN NOT BE........ I hope it runs good enough this time !
Unless you can step out of the boat and walk to shore with your working cellphone.
Water will never be solid like dirt !!! Stop risking your life !!

 

[tphoyt]

After reading your other post take a good look at the fuel you use and put back in your power equipment can to be sure it’s not contaminated.
It may be fine but it’s worth ruling that out.

 

[Drivewayboater2]

Wow… that’s an incredible story!

35 years of boating I’ve got stories too. From running on the cheasapake and hitting low tide( early on in my boating career) sucking up crud in my Force 70hp 2 stroke. Shutting motor down and having to paddle 1/2 mile to shore with the motor tilted up. That was a special day. Luckily the marina where I stayed let me flush out my motor.
Another being on Lake Wallenpaupack in PA and the engine just quit. Strong winds and being pushed to rocky shore. Tried everything to get restarted. No luck. Dropped anchor and waited for a passer by for a tow. The reeds on the motor were toast. Replaced that season and kept going.

with regard to your motor situation Nordin is spot on. Spark is key. Good fuel. then check fuel pump, clean carbs……if these havent been maintenced it’s time to address them. It’s a 36 year old merc.

good luck hope you can get things sorted out.

 

[l008com]

OLD... any boat motor..... CAN NOT BE........ I hope it runs good enough this time !
Unless you can step out of the boat and walk to shore with your working cellphone.
Water will never be solid like dirt !!! Stop risking your life !!

uhhhh, what?

 

[l008com]

After reading your other post take a good look at the fuel you use and put back in your power equipment can to be sure it’s not contaminated.
It may be fine but it’s worth ruling that out.

That gas isn't too old either and I use it every week. Plus I drove the boat long enough to definitely use all of the fuel from the driveway test in the fuel line and carb bowls so I'm pretty confident theres no problem there. My lawnmower gas tank is also one of the modern unvented ones you have to push to release the gas. Which is a pain BUT it does keep the gas very clean.

 

[tpenfield]

Do the spark testing before you give another thought to the gasoline.

 

[racerone]

Nobody can see or touch your motor !-----Do some trouble shooting / answer questions to come up with a happy ending.

 

[l008com]

Do some trouble shooting / answer questions ...

I don't often have time to work on my boat motor, this is going to be a slowwwww process where i update every week or two.

 

[cyclops222]

Some people love to risk their lives. Just to go boating.