Major Problem? Ign off while running.

[wileecoyote]

Made a huge mistake today. Waited too long at Fairview Aquapalooza and had to try and outrun the storm home. Big waves, Lightning, and Rain. Anyhow 3/4 of the way home I noticed the bilge blowers were on. I reached down to turn them off and accidentally hit the ignition breaker for the port engine, this was at about 3K 23Kts. Then I made a bigger mistake and quickly turned it back on, motor started up while still in gear and I slowed to see if there was any damage. There seemed to be a noise from the engine when loaded even though oil press and all other gauges look fine. With the lighning,rain,2-3 ft waves, etc I didn't want to stop and look at it right then. Made it the rest of the way on SB engine only (what a bear to drive, thank God the wind was on port side and helped push back to SB) Once I got to the dock, I started it and used to to dock the boat (I had to, it was the only way to get it in) and started. It sounds to me like maybe it backfired and burned out one of the exhaust manifold gaskets? I'll have to take the hatch off tomorrow and see if I can find a leaking gasket somewhere. I'm hoping that I didn't stretch a rod, or mess up a wrist pin. It's hard to tell. Any help would be appreciated.

 

[wileecoyote]

It was about a sec from off to on. So quick that the motor never really actually stopped, but there must have been enough fuel to cause a backfire. Sounds now after removing the hatch and listening at idle that it's a lifter/valve tap, or exhaust manifold gasket leak. The more I listen, the more I'm leaning toward exhaust. I'll have to get a better look(listen) with a stethescope. I was hoping someone else had a similar experience, since the switches are so close.

 

[skibum]

I hope it turns out to be something minor so you can get back out there! Good luck.

 

[tobnpr]

So, is that kind of like "push-starting" a car? Torque from the prop spinning was enough to get the engine running again?

Sounds like it was pretty quick, but maybe a possibility of water ingestion? Boat moving rapidly through the water, water being scooped into the intake- but no exhaust to keep the water out of the engine?

That's what happens to people that put scoops on their generator intakes...

 

[wileecoyote]

So, is that kind of like "push-starting" a car? Torque from the prop spinning was enough to get the engine running again?

Sounds like it was pretty quick, but maybe a possibility of water ingestion? Boat moving rapidly through the water, water being scooped into the intake- but no exhaust to keep the water out of the engine?

That's what happens to people that put scoops on their generator intakes...

I'm not sure it was the prop that restarted it, I think it was so fast that it hadn't completely stopped. It was pretty much a off and on right after the other. Have another issue with my little boat, so I didn't get to look at it today. Keep the thoughts coming and I'll see what I come up with when I go down there.

 

[PlayDate]

Just so I have it right....your hand accidently pushed the pop-out breaker which interupted power to the ignition circuit. Then you restarted the engine how? By using the starter? This is where I am a bit confused. The starter normally won't engage the flywheel of a spinning engine. And an engine stops real quick from 3000 rpm if the power is cut.

If power was cut and the engine stopped the starter should not have activated if it was in gear.....unless the safety is bypassed. So, it seems a lot of things are happening at the same time.

Is it likely that when you cut power, the engine pumped more fuel into the intake manifold (throttle open, mechanical fuel pump, engine spinning ...no spark). Then when you restarted the engine.,,,,,boom either an exhast manifold gasket or heat crossover gasket got blown our of position? In either case.....it shouldn't be a big deal. A backfire normally will not hurt the engine components.

-John

 

[wileecoyote]

John, you have it right. I hit the port ign breaker. I turned it back on so fast that the engine didn't have to be restarted it went from 3000RPM right back to there. It was long enough that you could feel the boat lay down a bit to the port side, but then right back up. I think because I was at 3000, the fuel kept flowing and when I hit the juice back to it pop! Like I said my only worry was that a cylinder filled up with fuel and pow! Bent rod, or wristpin area crack. After thinking about it, I would think the pulse dampner and tranny would take some of the brunt. I'll hopefully check it tonight. Last night I had to drain the fuel from my little boat as the fuel tank has decided it no longer wants to hold liquid anymore!

 

[PlayDate]

John, you have it right. I hit the port ign breaker. I turned it back on so fast that the engine didn't have to be restarted it went from 3000RPM right back to there. It was long enough that you could feel the boat lay down a bit to the port side, but then right back up. I think because I was at 3000, the fuel kept flowing and when I hit the juice back to it pop! Like I said my only worry was that a cylinder filled up with fuel and pow! Bent rod, or wristpin area crack. After thinking about it, I would think the pulse dampner and tranny would take some of the brunt. I'll hopefully check it tonight. Last night I had to drain the fuel from my little boat as the fuel tank has decided it no longer wants to hold liquid anymore!

I would not worry about the ignition issue. It can't push enough fuel through the carb in that short of a period of time to do more than make a backfire. The fuel will pool in the bottom of the manifold and when the engine fired again it went boom. Unless you have a hissing noise from the intake manifold or a ticking from the exhaust manifolds ....you should be fine.

Sounds like the fuel tank leak is far more serious. Where is it leaking? Your tanks should be aluminum.

-John

 

[wileecoyote]

I would not worry about the ignition issue. It can't push enough fuel through the carb in that short of a period of time to do more than make a backfire. The fuel will pool in the bottom of the manifold and when the engine fired again it went boom. Unless you have a hissing noise from the intake manifold or a ticking from the exhaust manifolds ....you should be fine.

Sounds like the fuel tank leak is far more serious. Where is it leaking? Your tanks should be aluminum.

-John

The fuel tank is in my 87 bowrider. It was made by a company in the Eastern Shore who, from what I have been told, would get previous model year Wellcraft hull molds. It looks exactly like a 86 Wellcraft 200 elite. I siphoned all the fuel out yesterday and now need to cut out the floor and install a replacement. Seems Wellcraft, as well as this company, was famous for foaming the tanks in which let them marinade in water until they leaked. The aluminum tank looks like it's growing salt crystals all over it.

 

[wileecoyote]

OK, update on the big boat. Started the port engine to see what all the racket is. Terrible exhaust leak on the SB manifold between Cyl 4 and 6. I wiggled my head down between the exhaust hoses(with engine off of course) and you can see the soot where it's leaking. I can't actually see blown gasket, because I didn't have a mirror, but it feels like holding your hand over a tailpipe. It blew it out GOOD! I'm gonna order gaskets for both sides, in case the other side blew out too, and I can't hear it for the noise on the SB side. This will give me a chance to remove the riser and get a good look inside to see how far it is along to being rotted out.

 

[Nehalennia]

Check your oil too. Make sure you didn't suck up some water. To me it sounds a little too violent for just an exhaust leak.
If you did suck up some water, start changing oil immediately. Let it run at least 30 minutes between changes. I'd change it a minimum of 3 times(with new filters too)

I hope it's just the gasket

 

[wileecoyote]

I will have to check, but I hope not. I'm not sure there was enough time for water to be injested, but there was time for fuel to puddle I guess. Anything is possible!

 

[Nehalennia]

I will have to check, but I hope not. I'm not sure there was enough time for water to be injested, but there was time for fuel to puddle I guess. Anything is possible!

There was easily time, All it takes is one gulp without back pressure, especially with the "drop off" you mentioned.

I hope I'm wrong but go check.

 

[wileecoyote]

There was easily time, All it takes is one gulp without back pressure, especially with the "drop off" you mentioned.

I hope I'm wrong but go check.

I'll check it tonight Todd, Thanks for the idea, something I would have never thought of. I usually translate things from car applications, so that would be a strange phenomenon to me. I have heard of the sucking effect when the motor cuts off. Just not something that comes immediately to mind.

 

[rondds]

Mark
Sorry abt all that's happened but I'm learning a lot here. I had no idea a quick shut down could cause such a cluster-Fk. Still another reason to keep kids away from the controls. If a quick shut-down were to occur at that speed, what would be the course of action? Throttle back the other engine and let the boat come to a "stop" before re-starting?

 

[wileecoyote]

Mark
Sorry abt all that's happened but I'm learning a lot here. I had no idea a quick shut down could cause such a cluster-Fk. Still another reason to keep kids away from the controls. If a quick shut-down were to occur at that speed, what would be the course of action? Throttle back the other engine and let the boat come to a "stop" before re-starting?

Yes. I don't think there would have been any problem had I moved the shift lever to neutral and slowed to a stop and then refired the engine. It was the quick, ninja like, reflexes that got me in trouble. I ordered the gaskets yesterday and will be out of town until Sat, so hope they will be here when I get back so I can install them.

 

[wileecoyote]

Replaced the SB side manifold gasket today. Manifolds didn't look to bad, but I'm guessing they won't be more than a year or two before something happens. I got the manifold off and the gaskets were that green FelPro looking gasket. Anyhow, I can see why it was so easily destroyed. The stuff was so brittle, it cracked like a potato chip! The Merc gaskets I got have the soft silver coating. I did one side, and I can tell the port needs to be done as well. So far all else seems OK. Nothing in the oil and seems to run good, all gauges read OK.

 

[Sundancer]

I've done the same thing without issue. I've been trying to find some missile switch covers to prevent this from happening! I've done it about three times with my knee and it's a bit frustrating!

 

[wileecoyote]

I've done the same thing without issue. I've been trying to find some missile switch covers to prevent this from happening! I've done it about three times with my knee and it's a bit frustrating!

I probably would have been fine, except, quick reflexes and instinct made me flip it back on 1 sec later after additional fuel had puddled up.

 

[lucknow]

I have the same boat and have had the same experience!
I had no issues when it occured to mine however. Just restarted and has ran fine since.
It seems to me you are correct with the backfire scenario, If that did occur, I will be curious to see if the exhaust gasket is the failed item. For that to occur, the backfire would have had to go out the exhaust side and not the intake. You would also think that a noise out of the exhaust port from that side would have been noticed at the same time. You would also think that the exhaust explosion would force all of the water out of the muffler and it would get loud briefly until the water level builds back up to silence engine again.
I must admit, It has me curious. I hope it is nothing major for you. I will follow this post to see the outcome in case I have a simlar issue in the future.
Good Luck
Kevin