39 Flooding Problem

burly

burly

Senior Member
I've taken the 39 out for a few short drives and it's developed a problem running rich. It will start out fine but within a 10 mile trip it loads up and begins to cut out. You will begin to smell the gas. When I pull the plugs they're covered with soot. I've leaned out the air gas adjustments, replaced the needle and seat and re-checked the float adjustment, and replaced the power valve with no results. I've even replaced the carb with one off another running flathead and it still runs too rich. I'll clean the plugs and it will run fine for short time but then load back up again. Just wondered it you guys might have any suggestions. Thanks guys.
 
What sort of fuel pump are you running? If it is electric, you need a regulator. Stories abound regarding new mechanical pumps with too strong a spring. It could be too much fuel pressure keeping the float from closing the needle valve.
 
float could be leaking and sinking....or still could be too much pressure from fuel pump overcoming the float....Mike
 
Mike in AZ said:
float could be leaking and sinking....or still could be too much pressure from fuel pump overcoming the float....Mike
Click to expand...

That's what I was thinking. Original type replacements have, I've gleaned, too much spring pressure. Once way to know is to take your replacement pump apart and replace the spring with one from an old pump. If you don't have an original, perhaps Ken Ct. or someone lurking would have an extra.
 
Had the same problem. Change the carb twice and then desided to go withe the new 97's same problem. Installed a pressure regulator and pressur gauge and found out the fuel pump was putting out over 4psi. The pump was astock pump with a glass bowl. After cranking down to a less tha 3psi, the car hasn't ran that good in two years.
 
A long time pump/carb re-builder told me ( as the diaphragm ) gets older it dryers out and will OVER-PUMP ... He also said "time to re-build " or carry a spare .... OLD...BILL
 
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