<VV> 64 turbo acceleration issues

[Frank DuVal]

I have no idea why a regulator would help gas dribbling after shutoff. 
Since when would gas pressure be higher with the engine off? It should 
be the same, as gasoline pressure is developed only by the spring in the 
fuel pump, not the stroke. Many people can not grasp this concept...

If you are thinking the heat of the shut off engine is raising the 
pressure, then what is the regulator going to do? It can only limit the 
flow of gasoline from the fuel pump into the gas line between the 
regulator and the needle/seat/carb inlet. If the engine is shut off, no 
gas flows. Therefore no regulation.

It's not like the regulator spits out the excess pressure through a vent 
hole. That would be exciting!

The return line system used on turbos and late late production adds 
another wrinkle to the normal system described above. The return line 
VENTS the gas line from the fuel pump to the carb/needle/seat. So, when 
you shut off a normally plumbed turbo, the gas line pressure between the 
fuel pump and carb drops to ZERO. So what will a regulator do? Nothing.....

Unless you plumb the regulator between the fuel filter and the carb, in 
which case the line before the carb might not vent through the return 
line, thus causing a problem, not fix one.

So, if the fuel line pressure drops to zero (make sure the return line 
is clear back to the tank) and gas still drips in the carb, the fuel 
level in the carb is where I would start troubleshooting.

If the accelerator pump has a hole in it, the symptom will be rich 
mixture at idle. Then as the hole gets bigger, rich at speed too.

Comments, Smitty?

Frank DuVal

Flame suit on, as we are playing with gasoline here!

On 11/9/2011 8:48 AM, Kurt Guttensohn wrote:
> Ok,  Thanks for everyones input so far.  Here is what I am going to try:
>
> For the dribbling gas after shutoff
> 1.  install a fuel pressure regulator and gauge.  I will probably have to order one.  Anybody have suggestions.
> I had a cheap'o regulator on there that I removed because the car wouldn't start with it on and wide open any more.
> - I do have a return line, that seems to be functioning well.
>
> For the stumbling during acceleration
> 1.  Try replacing the Pertronix setup with a spare setup I have.
> 2.  If that does not work, I will dig up the old points and condensor and try that.
> 3.  Check the accelerator pump.  Only about 1 year old, but it could still be an issue.
>