60hp Falls Flat on It's Face......Sometimes

[Snowfish]

Looking some wisdom here???????..

I have a 1998 60hp Merc (3cly 2stroke, not big foot) on my pontoon. While at WOT, after a period of time, it will fall flat on it's face, sometimes. Like it's starved for fuel. Or sometimes it will run fine at WOT until I back off a little. Then it falls on it's face again, sometimes. If you catch it, and throttle back, it will spit once or twice, and then idle fine. It will idle all day long, but try to throttle up, and sometimes she goes, others you have to work it a bit. Sometimes I have to hammer it to get it to throttle up. Others it's more of feather it up.

I've cleaned both tanks, to remove floating sediment and debris. I removed, rinsed and blew out the fuel pick ups in the tanks. In addition, I replaced the fuel filter. I cut apart the old filter and saw some debris, but not a huge amount. My tanks did have a bunch of random crud that was obviously plugging the pick ups.

I thought perhaps I'd missed some of the "floaties" in the tanks the first time. But it acts the same on either tank.

I'm thinking there's some debris in the fuel pump that sometimes blocks the flow and other times doesn't, depending upon rpm or maybe wake action? So, fuel pump rebuild or maybe just a good cleaning?

Or the carbs need to be tore down and rebuilt?

Any insights, comments, and wisdom would be greatly appreciated.

 

[Snowfish]

Re: 60hp Falls Flat on It's Face......Sometimes

Just read one of the other "fuel starvation posts" and someone mentioned a loose carb. mmmmm........going to check that tonight. Any advise is more than welcome. Thanks.

 

[Snowfish]

Re: 60hp Falls Flat on It's Face......Sometimes

I'll bring this to the top and then let it die if there's no additional insights.
Carbs are snug. I'm going to try a new fuel pump or rebuild kit. Any other ideas? Thanks

 

[sschefer]

Re: 60hp Falls Flat on It's Face......Sometimes

Sounds like water in the fuel to me. Any problems starting it?

 

[Snowfish]

Re: 60hp Falls Flat on It's Face......Sometimes

Always starts like a champ. Fresh gas in both tanks since the rinse/flush. Even when I don't "catch it", when it totally cuts out, it will start up no problem. My local marine dealer needs $115 for the fuel pump/kit. I think I'll tear it down, clean it out, and she how she goes. or just spring for the new pump since it is getting up there in years. Thanks for the reply.

 

[westexasrepublic]

Re: 60hp Falls Flat on It's Face......Sometimes

mine basically does the same thing, 70hp mariner, and I too have changed all the fuel lines and connections? ill follow, maybe someone will answer your thread...

on my dads 150hp Mariner it was his rectifier, so after doing all the fuel you may want to go to the next issue electrical.I watched this video today and it gave me some good info on what to do...http://www.youtube.com/watch?v=GP7ni_MEkH4

 

[BoobieBouncer]

Re: 60hp Falls Flat on It's Face......Sometimes

It could be the fuel pump, but that sucks if you spend the $115 and it doesn't fix it...

Maybe your high speed jets are dirty on your carbs or your carb floats are set too low?

 

[CharlieB]

Re: 60hp Falls Flat on It's Face......Sometimes

It is more likely that a carb has a bead of water laying in the bottom of the float bowl. It just lays there minding its own business until the fuel flow at WOT sloshes it around and it finally gets sucked up against the main jet, plugging it off and that cyl dies, the motor dies, everything comes to a halt. With no vacuum to hold the bead of water against the jet, it just falls back to the bottom and lays there, until next time.

Look at your carbs, see if there is a brass drain plug on your model. Remove one at a time, pump the primer bulb to help flush out anything that is in there, put the plug back in and then do the same for all remaining carbs.

Add water and stir, keep your fingers crossed. (Launch the boat and test it out)

 

[CharlieB]

Re: 60hp Falls Flat on It's Face......Sometimes

Oh, and check the parts section here at iboats for a fuel pump rebuild kit. It should even be half of what that dealer want. He must be trying to sell you a NEW pump ASSEMBLY.

Have your model and serial #'s handy.

 

[Snowfish]

Re: 60hp Falls Flat on It's Face......Sometimes

I'll see if there's drain plugs. Don't recall seeing them, but can't say I was looking for them either. Now the water in the carbs makes sense, since sometimes it's like only one or two cylinders are dropping out before the whole thing falls flat on it's face. I'll give 'er another shot after work......................

 

[iraqarmyvet]

Re: 60hp Falls Flat on It's Face......Sometimes

this is what I encountered with my 1971 115hp that was doing the same thing.

I was flying down the river and BOOM it killed on me. once i got it back I looked at it and no spark.

what i found was in my key switch, loose wires and a bad key switch.

I thought it was starving for fuel too but it was cutting in and out because of electricial problem.

its always a good idea to replace fuel filters, carb cleaning that type of stuff every few years.

anyway good luck.

that is what did it for me anyway.

 

[Snowfish]

Re: 60hp Falls Flat on It's Face......Sometimes

Pulled the carb drain plugs tonight. Very simple to get to. Flushed the daylights out of them. Hard to tell if there was water in there, but if there was, there ain?t any more. Then I noticed gas pooling in the lower casing. Found the drain pipe with the small check valve. Totally plugged with bugs, sludge, and crud. Cleaned it out so she would drain again. Took it for a spin to try to duplicate the symptoms. Ran like a champ! But it was a shorter than normal run since I?m down to about a ? tank. (other tank empty) I?ll do an all afternoon run Saturday. That should tell the story.

My theory is this, CharlieB & sschefer are geniuses! I had totally ruled out water in the gas, but humbled myself because I have knucklehead tendencies. Since pontoons generate a tremendous amount of turbulence, I bet the motor casing was filling up with water, eventually sucking up water particles through the silencer. Now that the drain is clear, she should drain better.

Fingers crossed here. Water in the carbs or water in the case. Both will put a hurting on performance. Thanks for all of your help. I?ll post again after the weekend run.

 

[Snowfish]

Re: 60hp Falls Flat on It's Face......Sometimes

Beautiful day! Nice long cruise. Crappies were biting, Bass wanted to play, and the Sunnies just wouldn't stop! And neither did the boat. Total range flawless. Nice work all. Water in the gas and engine housing was the problem. Seems to be dialed in now. Thanks for your help.