Flooding problem

JMFL36

JMFL36

Senior Member
Seems like one problem after another trying to get my '54 Mercury 256 Y Block to run smoothly. First it was the Holly teapot 4 barrel carburetor, so I replaced it with one of Sal's carbs. Next it was a fuel supply issue that turned out to be a mud wasp nest blocking the gas tank vent tube. Now I'm having a flooding issue. The car start and runs fine for about 10 miles. Then I start smelling gas and the car quits. Open the hood and take off the air cleaner and I can see gas dripping from the carb at the accelerator pump rod. Wait for an hour or two and it starts right back up, runs for about 10 miles and shuts off again with more gas leaking. I am running a stock Ford script dual action (Fuel/Vacuum) pump, with no electric pump assist. I took the top off the carb, manually filled the bowl, then tried to blow air through the fuel inlet port. I can not get any air past the shutoff needle valve. So I doubt its a float adjustment or needle valve problem. Has anyone had a problem with a stock OEM pump providing too much fuel pressure to the carb? Can the pump be adjusted? Any other causes you can think of besides excessive fuel pressure? I have not put a gauge on the fuel line yet to measure the pressure, as I wanted to check here first.
 
Has anyone had a problem with a stock OEM pump providing too much fuel pressure to the carb? Can the pump be adjusted? Any other causes you can think of besides excessive fuel pressure? I have not put a gauge on the fuel line yet to measure the pressure ...
Click to expand...

You have to know the pump pressure and volume delivery.

Connecting a pressure gauge and measuring at idle only will not ID all possible conditions. You need to road test with the gauge taped to the WS after measuring pressure/volume delivery @ idle (SPECS IN WSM).

Has the fuel pump been replaced lately? You do have a quality fuel inlet filter? Running E10 gasoline?
 
I run only ethanol free gas. The pump is a Ford script OEM pump that I rebuilt with modern components. Gas tank is new. I do not run a fuel filter other than the strainer in the pump's glass bowl.
 
JMFL36 said:
I run only ethanol free gas. The pump is a Ford script OEM pump that I rebuilt with modern components. Gas tank is new. I do not run a fuel filter other than the strainer in the pump's glass bowl.
Click to expand...

If the spring in the kit was not calibrated exactly for your application, it may produce too much pressure.

There is no filter, only a brass screen? Can you show a photo?
 
Here are photos of the pump and the carb showing where gas is leaking after about 10 miles of driving. I emptied the pump gas bowl so you can see the screen inside a little better. Somehow gas is filling the accelerator pump chamber, overspilling to the connecting rod, and running down the rod and out the carb. I'm stumped.

IMG_8668.jpg

IMG_8662.jpg

IMG_8648-2.jpg
 
I suppose it's possible the float is slowly filling with fuel. If the fuel pressure isn't the problem.
If you feel comfortable doing it, remove the float axle and float. Then shake the float to see if you hear sloshng inside of it. The '54 float was unique in that the pontoons were slightly lower to clear the secodary fuel tubes, but think I may have one.
If that's the case, I'll send you another float at no cost.

Sal
 
... hmmph ...

Good thing Ol' Sal is here as I never considered a sinking float ... :o

(... well after fuel pressure anyways ... )

OH!

THANX! for those photos, really appreciated.

Did the car come through with a 256? Quite unusual unless PI.

:confused:

- ANOTHER KULTULZ EDIT -​

It's a MERC DUMB-A$$, not a FORD ... :rolleyes:

It's getting worse daily ...
 
Last edited:
Yes, the car has it's original 256 per the cast markings on the block by the carb. All stock. I just picked up a fuel pressure gauge and the right tee block to plumb it into the steel line. I'll post some photos and reading when I get it installed over the weekend.
 
Well, I plumbed a fuel pressure gauge into the steel fuel line today right off the fuel pump. Ran the car at different RPMs. At idle it reads 4.5 PSI, and at higher RMPs it never goes over 5 PSI. So I think I can safely rule out the fuel pump as the cause of the carb flooding. To see a short video of the gauge readings go HERE. I'm going to ship the carb back to Sal to go through it.
 
Last edited:
You must log in or register to reply here.
Back
Top