Starting troubles Mercury 7.5

[Insanity]

sounds like the carb is out of tune - did you check the plugs to see if they're loading up and getting wet or if it's running lean?

New plugs and there wet every time Ive taken them out. Can't keep it running long enough to check to see if there reading lean or rich. It stumbles while running wide open and is still smokeing so I'm betting it rich enough.
Less it does as I mentioned above. No dought its lean when it screams rpms like that. Problem is what's causing it the carb or a leak. I've done lots of carbs. This thing is so simple Compiared to others I've been in. I don't see anything wrong with it. It should run. So I'm guessing I've got and air leak somwhere. Now how to find it.

 

[onthewater102]

From what you'd described prior to me posting I was thinking you're running too rich, based on you're able to get it to run @ WOT but not any slower it sounds like you need that much air to keep it going, and that it's loading up on you at lower RPM's where the air is slightly restricted. The wet plugs are consistent with it being too rich as well. I'd get it ripping on the water and start tightening the mixture screw until you start losing RPMs @ WOT then ease off it a smidge (~1/8 turn) until they rebound then a smidge more so you're not running too lean WOT. You've got fuel and you've got spark, if it isn't an adjustment then you've got to pull the carb again & thoroughly clean it and snake the passages through it.

I don't know what type of seal you think could be leaking - on a 2 stroke you've got the head gasket, the reed valve assembly and the gasket between the carb and the intake...that's it on the vacuum side of the system.

 

[JMichael]

I'm no expert on motors but I think a 2 stroke draws fuel through the crankcase so the oil can do it's job of lubricating things. So I would think that any gaskets that seal the crankcase could leak and cause a lean condition.

 

[onthewater102]

yeah - but you're looking for a leak substantial enough to impact the engine @ WOT with all that fuel...my engine really only has the cylinder block cover (i called it a head gasket, but as there ins't a true head that's not correct terminology) yours isn't too much different:

not a lot of options in there...intake cover gasket?

 

[Insanity]

Perfect! Onthewater part number 21,s gasket was weeping oil out the bottom not to much just a couple of drops. I'm hoping that was it. The pistons are behind it. I was told it was a transfer port cover. Whatever that is. :mrgreen:
But the Pistons come past the opening of the ports so I'm guessing it would suck against it pretty good.
I couldn't get a gasket for it from the shop today so I cut one and sprayed the heck out of it with High Tack permatex gasket sealer. Waiting for it to cure over night maybe it will run correctly in the morning figures crossed. [-o<

 

[Insanity]

Well I tried starting it this morning. Got the same results. I may shoot holes in the dang thing before I get it fixed.
Someone on another forum is walking me threw One step at a time of things To check. I'm thinking the crank seals are next. ( I hope they no what they are doing ).

 

[nlester]

I hope they can help you. Someone's check list worked for me.

 

[Insanity]

Well I gave up and took it to a shop Sunday. He called this afternoon to ask what the problem was. It was peering like a kitten. Starts first pull every time. :shock: he didn't do anything to it.
Only thing I can think of is that gasket I put in was one I cut. And the material was pretty thin. Maybe for some reason the high tack gasket sealer hadn't set by the next morning and it still sucked air. I did spray it thicker then a normally do. Because I figured it had a ton of vacuum plus gas/ oil in contact with it.
Maybe by Sunday and Monday it dried.
Anyway I'm taking him the boat tommorrow so he can run it and make sure it's rite. Because I had only took him the motor before sense it was 30 miles from home.

 

[Triple obsession]

Did you take him your fuel tank & hose along with the motor or did he have his own?

 

[Insanity]

I took him mine.

 

[nlester]

I hope you are getting ready to get on the water in your next post.

 

[Insanity]

Purs like a kitten my foot. :evil:
Took the thing to the river today. At first it started right up ran a about ten seconds and died. No problem it's cold natured rite. Wrong. It just kept getting worse till it wouldn't start at all. So I shoved it off in gear wide open. :mrgreen: it starts fine like that.
Ran it around for about 15 mins anytime you get to low on the throttle it will die. And forget about it idling unless it's wide open. And not to long then. It will die all of a sudden like you hit the kill switch.

The guy said the carb was set. And I asum he played with it. Starts awful good when you first start. His compression gauge read the cylinders at 125. And it ran fine for him. My farther in law took him my boat and watched him run it. And it ran fine.
So what would make it act like that? Fine one min and crazy the next.
It run the same way in my water barrel as before. But acts better in the river with less turbulent force in the prop.
Atleast it didn't rev to the moon today.
Any ideas guys?

 

[JMichael]

If the mechanic checked it out and it ran fine, I'd take it back to him and have him show me "fine". Then find out what he's doing differently than what you are doing. Either way, one of you is going to show the other one something.

 

[Insanity]

I've got a good mechanic rite up the road from the house. There just running behind rite now. Il be taking it to them next.
The guy that worked on it this time is just to far away to keep messing with. And he didn't charge enough for me to worry about.