Nissan 8hp 2 stroke fuel delivery

[Kona fisher]

fuel delivery problem driving me nuts

About to Sinjin from a friend looks like it's hardly if maybe never been used but you wouldn't starts at first when I how does the fuel is flooded the cylinders with fuel but I adjust the floats and got that problem taken care of but now no matter every time I try to start it it won't start and there's good spark but I take the spark plugs out and there's absolutely they are absolute bone dry I know I changed the Jets on the carb I know that the carburetors got fuel in it and but for some reason it's not getting from the carburetor into the cylinders and I cannot understand why I know the Jets are clear I know there's fuel in the carburetor there's good compression it's like Satan's inside this outboard I even use a drill to turn it over and will not fire at all and when I look inside the cylinder there's just zero fuel it's from the carburetor to the cylinders any ideas? I've taken the carburetor off at least 10 times there are these little valves between the carburetor and cylinders they appears to operate just from the suction open and then closes them back. I have had many backyard mechanic look at it nobody figure it out I have sprayed starting fluid in carburetor but it doesn't seem to be making it to the cylinders either as there's no smell of the starting fluid in there and of course it's not kicking over almost does but it seems that with the lack of fuel not going to ever kick

 

[Kona fisher]

I bought this 8 horsepower Nissan engine from a friend looks like it's hardly or never been used but I have never been able to get it to start At first when I pumped the girl bulb fuel flooded the cylinders but I adjust the floats and got that adjustment I think pretty goodvery time I try to start it it won't start and there's good spark but I take the spark plugs out and there's absolutely no gas o the plugs they are absolute bone dry I know I changed the Jets on the carb I know that the carburetors got fuel in it and but for some reason it's not getting from the carburetor into the cylinders and I cannot understand why I know the Jets are clear I know there's fuel in the carburetor there's good compression it's like Satan's inside this outboard I even use a drill to turn it over and will not fire at all and when I look inside the cylinder there's just zero fuel it's from the carburetor to the cylinders any ideas? I've taken the carburetor off at least 10 times there are these little valves between the carburetor and cylinders they appears to operate just from the suction open and then closes them back. I have had many backyard mechanic look at it nobody figure it out I have sprayed starting fluid in carburetor but it doesn't seem to be making it to the cylinders either as there's no smell of the starting fluid in there and of course it's not kicking over almost does but it seems that with the lack of fuel getting to the cylynder it will nevrr kick. Aspen substantial hours with this motor and I just don't know what to do next I hope somebody can help I consider myself to be a decent mechanic but I think I'm going to have to throw in the towel but I'm not going to because I need it to wipe the tears

 

[ahicks]

If it's not firing on starting fluid, your problem is not likely a carb issue.

 

[Kona fisher]

Yes I can't find anything wrong with the carburetor. But just like the fuel when I spray the starting fluid and it doesn't seem to be making it into the cylinders I'm going to take a look at those valves in between the carburetor and the cylinders although they're free but maybe they aren't opening when the engine is turning over. I know the starting fluid isn't making it into the cylinders because it has a very distinctive smell which does not exist when I take the plugs out and the plugs are clean and dry

 

[Kona fisher]

Yes I can't find anything wrong with the carburetor. But just like the fuel when I spray the starting fluid and it doesn't seem to be making it into the cylinders I'm going to take a look at those valves in between the carburetor and the cylinders although they're free but maybe they aren't opening when the engine is turning over. I know the starting fluid isn't making it into the cylinders because it has a very distinctive smell which does not exist when I take the plugs out and the plugs are clean and dry. The fuel should be getting drawn in there,,, I don't know what the heck I'm missing and it's really not that complicated

 

[Kona fisher]

When I take the carburetor off and rotate the engine you know I feel good Impressions I don't feel any substantial section to the carburetor so where's that are sucking going? I can tell that's why no fuels going in there because it's not sucking so what do I need to do to make it suck?

 

[Kona fisher]

Compression not impression suction not section

 

[ahicks]

Have you checked the compression? Are both cylinders similar at something over 100psi?

 

[pvanv]

Have you checked spark? If so, by what method?
You can put a small spray of ether starting fluid in each cylinder and see if that fires.
Those reed valves are pretty reliable, so I doubt those are stuck.
What is the compression?
How did you adjust float height?
Did you Properly clean the carburetor?

 

[Kona fisher]

Yes I checked the spark by turning the engine over and looking at the plugs. The carburetor is clean as. A whisle, new jets too for good meassure. I checked compression I think is was around 90, but not sure now I checked it so long ago but even if it was low it should be enough to pull some fuel into the cylinder but no. Last night Pulled the carb again and rotated the motor while look at those valves and they didn't open even a little. I pulled the valve plate off again and those valve open easily with just a little finger pressure. I put my hand over the intake where the vLve plate was(you can see the connecting rods and where the attach to the crank. When I turn it over by hand I can hear the sucking and blowing pistons but cannot feel even an ounce of air movement where I put my hand over the manifold. So with no air movement across the Jets or through the carburetor of course there's no Venturi effect and no way for the gas to get to the cylinders. Same thing when I sprayed in the starting fluid through the carburetor never got past the valves because there was no suction to open them. I've never seen this kind of problems before honestly usually the intake manifold is on top of the cylinders not having to pull the fuel through the rods and crank and so forth before actually entering the cylinders. So there it is I don't know what's stopping the air flow so I guess I have to just take it apart and see if I can figure it out unless somebody knows about a diaphragm or something in there that might be broken or whatever I'm surprised this isn't problems is seen more often because it's completely catastrophic to the engine being able to run at all yet the engine appears to be perfect. Anybody that has any advice on this had some experience with this kind of problem please let me know cuz I'm not even sure how or the exact path of the fuel flow past valves appears to be several ports could be the ones to carry fuel. I thank everyone who is taking the time to respond I don't really see anything in the book about this and I'm still feeling around the dark at this point about how to get that airflow working. When I start taking it apart on the top end I see any things or find the solution I will post.

 

[pvanv]

I would squirt a little starting fluid in each plug hole, reinsert the plugs, and see if it pops.
If a crankshaft seal (upper or lower) is completely shot, it will not pull vacuum, but that is rare.

 

[pvanv]

All 2-strokes pull the fuel mix through the crankcase to lube the bearings.

 

[pvanv]

Here is what the crankcase of an M8B looks like:

Do you have the dreaded M8A?

 

[Kona fisher]

First I want to thank you for your help. I don't thinkbI have the dreaded m8a the sticker says NS8B 3B2-1

 

[pvanv]

OK, so you have the 8B.

 

[LoweSuperior]

Compression not impression suction not section

Please, no grammar checking, just the facts . . . thanks