All Small Six Plug fouling

[kaden_.adams]

Hey! Recently rebuilt 200, my plugs are getting fouled after about a month of driving, old motor had this same problem. Im wondering, I have an electric fuel pump on the car because the last motor had a wiped out cam lobe for the mechanical one, its a 27gph pump, im wondering if this is the problem? It doesn't have an inline regulator, wondering if too much fuel pressure is pushing past the needle? And help it appreciated!

 

[pmuller9]

Yes, you should have a bypass fuel regulator, and the regulation pressure depends on the carburetor.
Which carburetor are you using?

 

[aussie7mains]

Quite possible, but you should have other symptoms like:- black smoke, excessive fuel consumption. the flow rating of your pump is more than you will ever need, but you might need a pressure regulator. What carby?

 

[kaden_.adams]

It is a holley 1904 I believe, and it is using quite a bit of gas, more than I feel it should be, havent noticed and black smoke though

 

[pmuller9]

It is a holley 1904 I believe, and it is using quite a bit of gas, more than I feel it should be, havent noticed and black smoke though

The Holley 1904 should not have more than 4 psi of fuel pressure to prevent flooding.
You should install a regulator that has a return line back to the fuel tank and a fuel pressure gauge right at the regulator.

Certain electric fuel pumps cannot be dead headed at the carburetor and must have a return line regulator.
Which fuel pump are you running?

 

[alwill923]

• Post #13
• Oct 10, 2025
• Forum: 144-250 "Small Block" Six Performance

I would always install a return regulator with an electric pump. Pick a pump with slightly more flow and pressure than you need and use the regulator to control the pressure. This will give you a steady pressure and by always returning fuel to the tank it keeps the gas to the carb cool, no vapor lock. Always put the regulator close to the carb. I have pictures of this in my build threads in the truck stop.

Also run the fuel line in front of the engine to keep it cool.

 

[kaden_.adams]

The Holley 1904 should not have more than 4 psi of fuel pressure to prevent flooding.
You should install a regulator that has a return line back to the fuel tank and a fuel pressure gauge right at the regulator.

Certain electric fuel pumps cannot be dead headed at the carburetor and must have a return line regulator.
Which fuel pump are you running?

Its just one from orileys, after spending 139 on a holley one and it took a crap i decided it wasn't worth it to put another on, how would I go about putting a return to the tank? It's a 1960 ford falcon

 

[DON]

Make sure the regulator has a port for the return line. The best thing at the other end is to get a sender unit that has a barb for a return line. Like this one:

https://www.cjponyparts.com/cj-classics-fuel-sending-unit-with-return-line-stainless-steel-mustang-1965-1968/p/FSU65/?year=1967&utm_source=bing&utm_medium=cpc&utm_campaign=Core%20Vehicles%20Shopping%20(Tier%202)&utm_term=4583451683749157&utm_content=Core%20Vehicles%20Shopping%20(Tier%202)

This method keeps the fuel to the carb cooler. You can just put a tee in out side the tank and feed the return into it, but then you have the heated fuel returning to the pump/ carb