Fuel pump to much PSI.

[340Duster247]

So my new pumped up 340 has been killing me running way to rich. I and lots of you on here have been trying to figure it out for the last month.
Did some messing around with the carb ect. And seemed to fix it. Well today I flashed her up and the car was sooooo rich my eyes were burning.

I have a 110 holley mechanical fuel pump that suposibly does not require a regulator ( this is what holley states). And has a automatic shut off at 8 psi.
But my fuel pressure gauge was reading 9.5 - 10psi! The weird thing is that some times the pressure is perfect at 6.

While the car was running I pulled the site plug and gas was of course spilling out.

Has anyone else had this problem with these pumps.

 

[fishy68]

I had one but didn't have high fuel problems. If anything mine ran on the low side (3-4 psi). I took it apart and all it had was 3 valves and a couple diaphragms. All mechanical pumps I've used run higher pressure when cold and drop a couple psi when warm. By your description I'd suspect the gauge being faulty since you say it jumps around. Have you tried adjusting the float levels? Should never be running out of the site plugs. Just a slight trickle is about right.

What carb are you running and what size jets are in it? What power valve is in it?

 

[jomoper]

Yup, my Holley mechanical pump was all over the place so I installed an inexpensive fuel pressure regulator. Prior to that the carb would puke fuel at some rpm's . Don't know what kinda carb your running but my Holley's manual says 6.5 psi max.