Fuel System: WW Stromberg 6-115 keeps overflowing despite numerous fixes.

[Craig]

Top gasket is saturated, flowing down sides of bowl, hard to photo capture.
Changed the needle seat several times for other NEW pieces.
Changed float for new.
Reset level lower.
Changed fuel pump twice.

Are there other issues with a 6-115 that could be causing this issue?

[PackardV8]

1. Temporarily install a fuel pressure gauge to determine exactly how much pressure the needle and seat are trying to hold back. Sometimes, a fuel pressure regulator is the solution.
2. When I have a carb apart, I sand the top of the body flat with a piece of sandpaper on a sheet of glass or piece of marble.
3. Sometimes, two gaskets are better than one.
4. Sometimes, a fuel filter with a return line is the answer.

jack vines

[Craig]

Why would a stock fuel pump overpressure the carb needle seat?
What is Studebaker Stromberg carb overpressure pressure?
Fuel filter with a return line all the way to the tank would seem to be a home made pressure regulator.
The top gasket on the carb would seem to be overkill as the level shouldn't be that high.
I see owners adding electric booster pumps to help stock pump.

What failures in the carb besides needle/seat could cause this?
Something failed with the accel pump circuit?
Could it be the fuel pump is not properly vented, causing it to overpressure?

[IndStudenut]

Just thinking out loud here...... But is it possible the float has a pinhole or something causing it to fill with gas and not shut off the gas flow? gasket may not be sealing but you are right.... the gas level should not be that high.

[altair]

You may have to do some bench testing, remove the carburetor and remove the float/needle and seat assembly. Assure the float is operating correctly by turning it upside down and see if it functions freely. Gently blow some air in to the inlet and gently raise the float and the air should be blocked. You can do a similar test with nonvolatile liquid, moving the float up and down should stop the flow. If for some reason he flow continues with the float fully raised there may be additional issues. The float may not be compatible with that carburetor or there is a crack in the housing and not allowing the fuel to stop. Over its lifetime it is possible that water was in the float chamber and froze causing a misalignment or a crack. A normal functioning fuel pump will not push fuel past a closed needle valve. Sometimes metal particulate from a contaminated tank can stick to the needle, fuel passing the needle can create a static charge and the small particulate can stick. Most modern needles have a rubber tip to avoid particulate sticking. Additional tests can include removing the drain plug in the fuel tank and store the gasoline in an approved container then pour in a gallon or two of nonvolatile liquid, design a long paint brush and swirl it around inside through the fuel gage hole then drain the contents in a clear container and inspect it for contaminants.

[bezhawk]

Make sure the float pivot pin retaining spring is in place and correctly seated under the casting tang.

[Craig]

I have had this 6-115 apart several times, each time replacing needle seat,
new stock, new rubber tipped, another new stock, recently new float.
lowered float set.

I have had other Strombergs apart (6-121) for rebuild as well and they all seem to have the same needle/seat.

[Craig]

Thanks to all.
I do have a new fuel tank and added inline clear body filter.
Received new fuel pump from eBay today.
Pulled out several pumps in inventory for this project.

This "new pump" appears to have the least impressive pump stroke and kind of a sloppy arm as well.
Could the fuel pump be the issue?
If a regulator is a fix, certainly the the pump is the issue.

I am considering putting this "new" pump in and seeing what happens.
certainly I cant be the only owner with this issue.

[mbstude]

Make sure the float pivot pin retaining spring is in place and correctly seated under the casting tang.

I have had this 6-115 apart several times, each time replacing needle seat,
new stock, new rubber tipped, another new stock, recently new float.
lowered float set.

I have had other Strombergs apart (6-121) for rebuild as well and they all seem to have the same needle/seat.

Craig, Brad is referring to the little wire spring clip that holds the float pivot pin in place. If it's missing, then the float could, well... Float.

Here ya go:

[Craig]

So went to Harbor freight, bought a $15 fuel pump pressure/vacuum gage.
hooked it up, started engine, and you see pressure gage at slow idle.




At idle it reads 6½ psi pretty steady, a little flicker.

Rev up engine and it reads 6-7-6-7-6 with a rapid wobble , probably matches pump stroking.

So what is the documented approved fuel pressure?



6½ psi seems high when ckd against shop manual showing a 4¾ psi avg.

What can be done to lower pump pressure?

This would seem to be a shared issue with all Stromberg carbs with new fuel pumps.
Is this a pump arm stroke distance issue?
Diaphram materials?
Pump arm dimensions?
Vent hole size?
Fuel pump spring?

[christophe]

Yes. Pressure seems to be on the high side. You can temporarily put à thicker seal between the pump and the block to lower it and see if the carb stops overflowing.

[yeroldad]

6psi is too high. Put a pressure regulator between the pump and carb. And, check that ebay pump real close. The arm looks different, and many people have said that those pumps don't work, because the arm is different and doesn't pump worth a poop.

[StudeRich]

I assume that you are using that "New" POC Airtex Pump Right?

My out of the Box idea: Open Up the vent on one of those 2 Real Carter Pumps and Plug the Pressure Reference Fitting Hole.
If these already Have Alcohol resistant Parts inside use as is. If not, rebuild one with the Kit from Antique Auto Parts.

These will last 20 -30 Years as apposed to a week to a year or two with those 2 Airtex's. I am surprised that the New one pumps, most have the wrong Lever angle and do not. Maybe they tried to fix that, and Overdid (over-stroked) it!

A side Note; On Used Pumps, I have found that a Bubble in the Diaphragm will cause over-pressure.

[Craig]

I am thinking of inserting a temporary shim gasket to space the pump away from the timing cover.
Loosen the pump bolts and slide this temporary shim gasket in place top and bottom , recheck pressure.

[StudeRich]

Not enough movement to matter, and then HOW Long do you think that Chinese Airtex will Last?

[christophe]

I would start with a 2 MM plate sandwiched between two paper seals and go from there. The plate can be made easily from aluminium and does not have to be perfect.

[StudeRich]

Are BOTH Check Balls installed?

One under the Accelerator Pump, the other in the Main Discharge Nossle Tower.

[Jeffry Cassel]

Can really only be 1) float level ;it is very important to have the float level spot on otherwise the needle won't seat. 2) too much fuel pressure, which you do have. It should be 3-5 psi. Any more can force gas past needle and seat valve. (This given that some of those tiny parts weren't lost!) My experience with ebay stuff has been less than good. The average seller doesn't know or care if it works or not and thinks that maybe this is for a Studebaker - or maybe a Rover. Not sure - doesn't care, can't send it back. Anyone want some new rear shoes for a Packard? They are only 1" too small.

[Ross]

The fuel pressure that a diaphragm pump provides is determined by the coil spring inside pressing on the diaphragm, not the stroke. You could take your pump apart and cut a coil off the spring.......................

[Craig]

didn't see this post, thank you.

So this is common practice in Studebaker fuel pump replacement?
You get a new spring in a rebuild kit?
What is the acceptable free length and spring rate for a fuel pump spring?
Maybe simply too much spring length causing too much preload?