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2006 Tohatsu 4hp 4 stroke

H

heritage2008

New member
So I have a MFS4B and since the outlet from the internal tank broke off (Previous owner didn't want to mess with it) I decided since I had an 8hp and 20 hp Tohatsu already I'd just plug in one of my tanks--yes, the 4hp has the male fitting already--but was leaking so installed a new one. I by passed the petcock and removed the drain back valve (looks like a larger Merc filter) and ran a hose from male fitting to a fuel filter then to the fuel pump. This motor Sat on it's wrong side for sometime (thank you PO) so I pulled the plug and pulled multiple times to clear oil--nothing came out. Motor wasn't used for sometime before I picked it up.
So changed oil and lower unit.
Motor fires on first pull while choked but when I try to push choke in slowly it dies--revs really high while on choke. I get the choke 75% in and it just gives up.
Pulled carb-soaked,, sprayed, checked float etc and had the 3 new gaskets. Repeat-does the same.
Already put in new plug when I changed oil.
Pulled fuel pump-cleaned and put back--not sure if diaphragm is good.....Put back on.....same result.
Fuel flows freely through the pump to carb when bulb is pushed so fuel is getting through.
When I started the engine and had the hose from pump to carb off--the flow was just a spit--hardly any came out--yes line and filter was full and under pressure.
The tank and line maintain pressure and the tank is vented.
So-----did the fuel pump take a crap?
 
The pump doesn't move a lot of fuel, and only a couple of PSI. Once the carb is full, it should run several minutes without adding fuel. Likely still a carb issue. PS the 6 hp carb will fit and work fine.
 
So what carb in 6hp fits this motor? All I have found have and extra port up top. Is this an over fill for the carb which would need a tube run downward to exit motor? Getting frustrated here. I order a 4hp carb but it had 2 small tubes sticking out the top and mine has none.
 
3JE032000M​
CARBURETOR ASSY, MFS/NSF6C​
​
$204.95​
Those are vents. The factory connects them to hoses to run outside the lower cowl. But they will work fine left disconnected.
 
I also have a 6HP Nissan NSF6BS. It has a carb with no upper port tubes. I want to replace the carb. Can I use the carb with port tubes and then just cap off the tubes?
 
The venturi size is different for the 4, 5, and 6. But all will interchange. I only use OEM carbs, not "universal" chinese stuff.
 
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