Vapor lock question

[newbiedmv]

I know this has been answered but I just came from a 2 hour 12 mile pain.

I have a 2005 50hp merc 2stroke. I'm up in pa learning it. It did well until the following. Putted 2 miles up a no wake zone creek @ under 2k rpm. Temp was 93 degrees.  Shut off to eat. Started again then shut down and stayed shut down. Got a 12 mile lift to get trailer. Still wouldn't start when I got back, raised motor up, loaded, straped down then it fired up.

I'm kinda thinking it loaded up with oil but a guy said might be vapor lock? Does this even still happen?

Thanks. I'm exhausted. 

[dickenscpa]

Vapor lock or maybe something called Heat "sink" or heat "seep." I had both on my previous boat. If I ran the big motor for quite a while and stopped to fish, if I trimmed the motor up fishing shallow (the way it was explained to me) hot gasoline would trickle back into the carb and it wouldn't start for a while. Not sure I explained it right or if the mechanic who explained it to me was full of crap, but I quit doing that and never had that issue again.

 

When I first got this boat it was the first boat I'd had with a knob on the outside of the gunnel to vent the gas tank. If I got to the lake and launched I could run about as long as I wanted but if I stopped and shut the motor down it wouldn't start back up.

 

I got back to the ramp, got home and was frustrated in the driveway and a neighbor walked over and I told him what happened and he said, "gas vent is shut." Never had that problem again either.

 

I had a bass boat from 16 yrs old until a few months ago and I'm 49 now. I sold it and dived head first in to kayak tournaments. My first boats were dinosaurs that would strand me by breaking down and being old and worn out. Around 27 I could afford nicer boats and got stranded a couple times out of ignorance. LOL! I had to burn my hand on the stove a time or two to know it was hot.

 

I think that's why I've gotten so into kayaks. I actually cover WAY more water in my kayak not worried about getting stranded. Nothing like paddling a 20' bass boat with a half paddle a few miles.

[TnRiver46]

I was going to suggest the gas vent but didn’t want to sound like a smarty-pants

[Way2slow]

The term vapor lock is usually associated with the fuel in the fuel lines or carb bowls getting so hot it boils and the vapor pressure pushes the fuel out of the lines or bowl, so there is no liquid fuel in their.

I've never had that problem with an outboard. 

Usually what you have with an outboard is referred to as heat soak.  That's where the block is warm enough to make the fuel in the crankcase evaporates out. 

Normally, when you shut an engine off, some residual fuel stays in the crankcase, so when you go to start it up again, there is plenty of fuel vapor to make it fire right up.  

With heat soak, the engine is too warm when you cut it off, and after is sits for several minutes, all or most of that residual fuel has evaporated.  A more common symptom of this is when you go running balls to the wall, kill the engine as you are getting into your spot, jump up and drop the TM and fish.  Then when you hammer down to take off again,  the motor dies.  Holding the primer in for a few seconds when starting off prevents the motor from dying.  That's heat soak.

Now, in your case, it sounds like you were not priming it properly, or your primer is not working properly because a healthy dose of gas will should let the engine start.   When you hold the key in to prime it, it's only pumping gas into the crankcase with the engine is cranking over, so you have to be holding the key in and cranking it at the same time.

I happen to have a 2006 90hp Merc and if yours is anything like mine, there's a fine line between priming it and flooding it, which happens very easily with mine.  If mine starts and shuts off, and don't won't to start again, it's flooded.  I have to push the handle forward a lot more, and be ready to  pull it back in a hurry, crank it over for several seconds without priming it anymore and it fires up.

So, the question is, did you maybe not prime it enough and are you sure your primer is working properly, or did you over prime it and flood it.  Either will cause it not to start, but it starting once on the trailer, makes it sound like you may have flooded it and it had just evaporated enough out over time and started. .

 

Do you have a water pressure gauge on your motor? Idling long periods with low water pressure will make one over heat.

Do you have a temp gauge on your motor to see how hot it was getting to.

If you have not had the thermostat out you might want to pull it and make sure the gasket on it hasn't swollen and restricting water flow. 

When was the last time you replaced the water pump?

If this motor was ever run in salt water, you might want to look at pulling all the covers off, exhaust and cylinders to make sure none of the passages are blocked with that white crud.  

Keep a wrench in the boat so if it does it again, you can pull the plugs out and look at them.  If they are very wet, it's flooded, if they are bone dry, it's not getting enough fuel.

 

 

[newbiedmv]

59 minutes ago, Way2slow said:

The term vapor lock is usually associated with the fuel in the fuel lines or carb bowls getting so hot it boils and the vapor pressure pushes the fuel out of the lines or bowl, so there is no liquid fuel in their.

I've never had that problem with an outboard. 

Usually what you have with an outboard is referred to as heat soak.  That's where the block is warm enough to make the fuel in the crankcase evaporates out. 

Normally, when you shut an engine off, some residual fuel stays in the crankcase, so when you go to start it up again, there is plenty of fuel vapor to make it fire right up.  

With heat soak, the engine is too warm when you cut it off, and after is sits for several minutes, all or most of that residual fuel has evaporated.  A more common symptom of this is when you go running balls to the wall, kill the engine as you are getting into your spot, jump up and drop the TM and fish.  Then when you hammer down to take off again,  the motor dies.  Holding the primer in for a few seconds when starting off prevents the motor from dying.  That's heat soak.

Now, in your case, it sounds like you were not priming it properly, or your primer is not working properly because a healthy dose of gas will should let the engine start.   When you hold the key in to prime it, it's only pumping gas into the crankcase with the engine is cranking over, so you have to be holding the key in and cranking it at the same time.

I happen to have a 2006 90hp Merc and if yours is anything like mine, there's a fine line between priming it and flooding it, which happens very easily with mine.  If mine starts and shuts off, and don't won't to start again, it's flooded.  I have to push the handle forward a lot more, and be ready to  pull it back in a hurry, crank it over for several seconds without priming it anymore and it fires up.

So, the question is, did you maybe not prime it enough and are you sure your primer is working properly, or did you over prime it and flood it.  Either will cause it not to start, but it starting once on the trailer, makes it sound like you may have flooded it and it had just evaporated enough out over time and started. .

 

Do you have a water pressure gauge on your motor? Idling long periods with low water pressure will make one over heat.

Do you have a temp gauge on your motor to see how hot it was getting to.

If you have not had the thermostat out you might want to pull it and make sure the gasket on it hasn't swollen and restricting water flow. 

When was the last time you replaced the water pump?

If this motor was ever run in salt water, you might want to look at pulling all the covers off, exhaust and cylinders to make sure none of the passages are blocked with that white crud.  

Keep a wrench in the boat so if it does it again, you can pull the plugs out and look at them.  If they are very wet, it's flooded, if they are bone dry, it's not getting enough fuel.

 

 

I flooded it. Yes the merc has a razor thin line between priming and flooding. It's literally magic touch. I will also try venting the tank.

I'm in south central PA now on an army flood lake to learn and really shake out the issues. I'm going back to my breakdown spot tomorrow as I can putt around with the 80 lb troller.

Hey this lake has massive stripped bass, musky, pike, trout, bass. Most fish are 140 feet down.

Thanks

Ps I stick close to the ramp.

Oh, had the tools as it's loaded up before or flooded. At this ramp I couldn't get a decent place to pull the plugs. The ramp was very busy. At 11 am with a 4 boat wait.

[galyonj]

1 hour ago, Way2slow said:

I happen to have a 2006 90hp Merc and if yours is anything like mine, there's a fine line between priming it and flooding it, which happens very easily with mine.

 

6 minutes ago, newbiedmv said:

I flooded it. Yes the merc has a razor thin line between priming and flooding. It's literally magic touch. I will also try venting the tank.

 

My old XP100 has a pretty dang thin line, too; even though I have to imagine that a lot of it's due to me being just a hair too slow on learning what it likes.

 

I don't have any suggestions for the OP, but I empathize.

[Way2slow]

Usually, you can tilt one all the way up and sit if on the rest if not power tilt and can take the plugs out no problem from inside the boat.  I say no problem, but make sure you have a spare or two in the boat, just in case one takes a dive.

 

I mentioned I push my control lever further forward, mine is a console mounted control on a pontoon boat and has a release button to disengage the shifter for cold start/fast idle.  Yours may only have the lever you pull up for fast idle.  You just want to try getting as much fresh air as you can into it when flooded.    

[newbiedmv]

I did think about that but was to tired and burnt. The cover is a very very tight fit. 

 

Could have been much much worse....a 12 mile tow ?.

I'll be in shallow water tomorrow,  if it stops raining for a few hours. 

[dickenscpa]

17 hours ago, Way2slow said:

The term vapor lock is usually associated with the fuel in the fuel lines or carb bowls getting so hot it boils and the vapor pressure pushes the fuel out of the lines or bowl, so there is no liquid fuel in their.

I've never had that problem with an outboard. 

Usually what you have with an outboard is referred to as heat soak.  That's where the block is warm enough to make the fuel in the crankcase evaporates out. 

Normally, when you shut an engine off, some residual fuel stays in the crankcase, so when you go to start it up again, there is plenty of fuel vapor to make it fire right up.  

With heat soak, the engine is too warm when you cut it off, and after is sits for several minutes, all or most of that residual fuel has evaporated.  A more common symptom of this is when you go running balls to the wall, kill the engine as you are getting into your spot, jump up and drop the TM and fish.  Then when you hammer down to take off again,  the motor dies.  Holding the primer in for a few seconds when starting off prevents the motor from dying.  That's heat soak.

Now, in your case, it sounds like you were not priming it properly, or your primer is not working properly because a healthy dose of gas will should let the engine start.   When you hold the key in to prime it, it's only pumping gas into the crankcase with the engine is cranking over, so you have to be holding the key in and cranking it at the same time.

I happen to have a 2006 90hp Merc and if yours is anything like mine, there's a fine line between priming it and flooding it, which happens very easily with mine.  If mine starts and shuts off, and don't won't to start again, it's flooded.  I have to push the handle forward a lot more, and be ready to  pull it back in a hurry, crank it over for several seconds without priming it anymore and it fires up.

So, the question is, did you maybe not prime it enough and are you sure your primer is working properly, or did you over prime it and flood it.  Either will cause it not to start, but it starting once on the trailer, makes it sound like you may have flooded it and it had just evaporated enough out over time and started. .

 

Do you have a water pressure gauge on your motor? Idling long periods with low water pressure will make one over heat.

Do you have a temp gauge on your motor to see how hot it was getting to.

If you have not had the thermostat out you might want to pull it and make sure the gasket on it hasn't swollen and restricting water flow. 

When was the last time you replaced the water pump?

If this motor was ever run in salt water, you might want to look at pulling all the covers off, exhaust and cylinders to make sure none of the passages are blocked with that white crud.  

Keep a wrench in the boat so if it does it again, you can pull the plugs out and look at them.  If they are very wet, it's flooded, if they are bone dry, it's not getting enough fuel.

 

 

Heat "soak" is one that I forgot. I've heard it called sink, soak and seep. I bought a new 1992 17' Bumblebee in 1992 and it had a 115 Merc on it that I had to handle with kid gloves. Heat soak was something I had to keep in the back of my mind at all times.

 

Also, if say I was going to a spot a ways out and was on plane for a while and trimmed the motor accordingly, when I began to slow down nearing my spot I couldn't idle along very far at all after a long ride or I would get the overheat alarm. I could trim the motor all the way down and just sit and the alarm would go off. I would have to shut the motor off a while. C&O Marine who is a very respected business scratched their head for a while and couldn't figure it out.

 

They politely asked me if I was sure I knew how to trim a motor. I told them I thought I did after all those years but I'm not above making a mistake. Flippers is less than a mile from C&O so we rode down there and to be honest if I was doing something wrong I needed to know. So we launched and he told me drive like I normally do. I did and we got the alarm and he confirmed I did nothing wrong, but they never could make it stop.

[newbiedmv]

 

Found what looks to be it.

Starts on starting fluid won't stay running. 

Fuel filter a complete opace white when I swear it was always clear before.

Called my boat guy, I evidently broke a law of boating around here. NEVER PUT PREMIUM GAS IN THE TANK.  It sits to long at the station and is 25% water.

Oh well I have two more days here I'll putt around the south end Thursday and Friday.

One thing I can say, in 10 years I've always learned something the hard way each time I go out.

But it's a little boat so I don't  have to

Bust. Out. Another. Thousand. 

Thanks to all you've been a great help

 

 

 

[newbiedmv]

If anybody sees this and has a comment please do so asap.

I'm going back out Thursday morning to another ramp. I'm thinking of not only cleaning the plugs again but shooting some carb cleaner in each clynider just to see if it will start (last time they didn'tlook bad at all just wet).

I'll stop at a few boat places coming back and get a few fuel filters also and talk with them. Although I expect a very high priced evaluation (hey that's how they make money here).

Anyway I saw a YouTube post about the ethanol drying up and cracking the inner layer of the fuel line, that clogs the filter. That and water (which I'll try to get the additive at 6 am) seems the best. Either way it will take some work at a pros to fix right.

Hey if I catch my PB it will be worth it who knows ?

[newbiedmv]

Another senior moment.

The valve in the squeeze ball is semi bad. Long story on how I found it.

Worked very well today, the old minn kota power drive auto pilot worked great.

The fish stayed 30 feet or more down.

I'll be back up here in Sep after the ski people leave.