Carburation problem

[KirkV]

Folks,

I have a problem, and the answer is not coming to me so let me throw it out there! About a week ago the car started missing and sputtering and then it would "disappear" and all was well.

I now have found what was happening and don't know how to fix it? I have a Demon carb... the speed demon actually, and what is happening is the carb bowls are filling up and overflowing into the carb and loading up the engine.

If I shut down the fuel pump all is well until the bowls run empty! If the car is idling the fuel stays about where it needs to be but when I put rpm's on the engine she will overflow every time.I replaced the needle valves even though nothing appeared wrong with them..... same thing. I checked the floats and all is well with them as well.

I thought possibly the fuel return line oriface may be getting plugged but found I do not have one on this car!
I thought possibly the fuel pump had a built in regulator for pressure and it was bad, but it is a Carter 152-875 rotary pump and there is no pressure regulator assembly on it.

Now my thoughts are that possibly the voltage is going too high and the rpm's of the pump are generating too much pressure by running too fast?

I will reinstall the pump tomorrow and check the voltage when at idle and when it is reving up to see if this could be the case. If this is it is there usually a voltage regulator on these cars and if so where is it typically located?

Sorry for soooo long but it has been a long process of not this and not this!

Thanks Kirk

[Grubby]

Too much fuel pressure. Check it with a gauge. It should be around 5-7psi. A new pump or a pressure regulator will likely fix the problem.

John

[KirkV]

But why did it work fine before and now it has a problem?

[Grubby]

Maybe the fuel pump is going out and pressure is up.

What are the odds that both needle and seats would go bad at the same time? If one bowl was flooding, I would say needle and seat. Both are flooding.

Checking fuel pressure is easy and gauges are inexpensive.

John

[jhv48]

A recurring problem with older demons. Unless you disassembled the carb, and cleaned it out when you got it, it could have casting shavings in the bowls and jets.