Ok, so I have rebuilt several of these before for cars, including my first FB 12a car in '97, and a couple since then. All have worked fine, and mainly just needed a new acc. pump diaphram I decided. Yes, the floats are at proper level.


!!!The difference this time, is this carb and engine were sitting a long time with old fuel- Engine is rebuilt with normal compression in Feburary. Since 2002-2005 had old fuel. Which has been drained and all fresh. I now have the car running great down the road, and throttle response and drivablity is fine. Its running slightly lean, probably from a vaccuum leak somewhere, but only causes a slight rough idle.

->The problem: When shutting off the engine hot-the carb bores above the throttle butterflies -primaries and secondaries start to flood over with fuel through the venturis. This is bad because some leaks past and makes starting it hot terrible since it looses compression from all that fuel and takes dumping oil down the carb to get the compression back. And because its a fire hazard when hot and fuel is leaking were it should not be....

Not sure if this is fuel system related-carcol canister-a check valve in the fuel lines or some other thing that causes fuel to go through the venturis.

YOUR THOUGHTS?

SO why is the fuel going over the top.

 

No expert here but a shot in the dark- Needle and seat may be varnished from the old gas making it stick open when hot? If you *lightly* tap on the top of the carb after shut down, see if it stops?

 

Actually, they are new needle and seat-hence the rebuild kit I mentioned.

 

Matte finish--- just went through (sort of) the same thing. New needles and seats have a finish on them, i read somewhere when rebuilding to put some 3-in-1 oil on them and work the floats for about 5-10 minutes gently up and down to wear off the finish and seat them. Since its all together, tapping on top of the fuel inlet banjo bolt did it for me. Do you have an aftermarket fuel pump and no regulator? that may also force fuel past the needles. Good luck!

 

stock pump, and its a 83, so it still uses the system were the pump is on in the on position without the engine running. Does not flood over when cold-ever. Only when shut off hot.

I did some spare carb parts to play with, including another Nikki top body-that includes the floats+needles and seats- still causes it to flood over through the venturis when shut off hot.

 

Is your vent solenoid working?

 

I'm not sure. But, I am guessing so if I tried to top carb bodies containing that solenoid. It does click when connecting and disconnecting it with the key in on position.