help with a flooding carburetor

Sounds like a stuck float.

I watched a Ferrari sales manager tap the carbs on a 275GTS that was doing the same thing a number of years ago at a car show. It did free up the float, but wisely I think, the owner opted to put the car on a flatbed and return it to the dealer for service anyway.

Engine fires are no fun.

However, my best guess is still stuck float, overfilling the carb.

D

 

1. As noted above, could be a stuck float. Also check to see if the float is still airtight (pinhole or broken solder connection)

Opening up the top of the carb will allow you to determine if the float moves easily. Taking the float off the hinge pin is not too bad a job, however the hinge pin should only come out in one direction. Plenty of instructions online or in Weber manuals

2. Could also be a worn flat valve that is not fully sealing. Float valve is easy to replace.

Diagnosis should be relatively easy because it is limited to only one carb.

 

Can also be a sunken float if it is an OEM brass type.

Take it out and shake it, if it has fuel in it, toss it.

While you are at it, 3 new floats + 3 new needle valves.

Best line of action would be a full rebuild of the carburation system.

Regards, Alberto

 

May well be a leaking float. Float stays down and fails to shut off valve. Had similar issue, some comment and photos here: http://www.ferrarichat.com/forum/206-246/520973-float-adjustment-40dcnf13.html
Kevin

 

Even if you identify the problem and fix the leak, be very careful before you attempt to crank the engine over with the starter motor. Are you familiar with the term hydro lock? It can occur when a cylinder gets filled with a liquid such as gasoline, and if it happens right before the compression stroke, you may bend a rod. To be safe, before using the starter, turn the engine over by hand through several revolution to make sure no hydro lock.

And just to be paranoid, also consider squirting some light oil into the cylinder that is being served by the leaking carb because all that gas has washed the oil off the cylinder wall of those fresh bores.

One more thing, your oil may need a change too because of the gasoline leaking in, pull the dip stick and take a sniff, you may get a surprise.

Tom in SoCal

 

More comments regarding the problem and my probability ranking
1. Stuck or sunken float, remove carb top to fix.
2. Bad needle and seat, remove carb top to fix.
3. A leak at a fuel fitting, check
4. Too much fuel pressure, check electric fuel pump rating, does the Dino have a regulator?

 

With fuel leaking onto the floor it sounds like an external fault rather than anything internal, is the engine running or just the electric pump?

Apart from a gasket leakage try the accelerator pump diaphragm, it has tendency to get brittle and leak.

To diagnose properly we really need more info.

 

I would remove the spark plugs before I turned the engine over if there is the threat of hydro-lock.