The fuel phantom

[keithwahl]

jIM.. I can turn electric on and off at will so it can be bypassed anytime... Fuel pressure will start out 6-7-8 and then decrease to 4 and car will perform poorly
Switch on electric and car runs fine. This is a "new" pump from Studebakers West... I will see if they rebuilt it and perhaps change it out but we pressure checked it
and it was performing as expected....

[altair]

I am suggesting the metal fuel line it self not just the pickup in the tank, check it for pin holes. You can check the fuel pump by inserting the suction inlet into some solvent and hand operating the lever and it should squirt liquid at least 6 feet. Try the soapy water test.

[bensherb]

Boost reference? At 4lbs boost, 4lbs of fuel pressure becomes zero. Right? I'm not sure of the Stude's opperation .

[55coupe]

I once had a 55 President that had the fuel line crushed were it crossed under the frame it was very hard to notice. The car ran fine at idle and for afew miles then would act as if it ran out of gas. Just another maybe good luck.

[jrlemke]

By "bypass" we meen disconnect the lines from the pump and connect them together!-Jim

[Son O Lark]

Did it have problems before you adjusted the float? You said it was too high. Maybe it was adjusted high to try to overcome your problem.

[keithwahl]

The steel lines are intact

[keithwahl]

the manual pump was not functioning and was replaced
the car was operating only on the electric pump
when the new functioning manual pump was installed then i started to have these problems

[studediesel]

How much supercharger boost pressure do you have when the car starves for fuel? Is the fuel pump to supercharger pressure line hooked up and clear?
Check manual pump output volume with the engine running.

[keithwahl]

Ross what would be a model pulse type pump...I am not sure what mine is

Keith

[keithwahl]

I can get up to 5psi when the car is floored
I am not getting any boost when starved
Fuel pump to supercharger is hooked up.. I would have to take the line off to check for clear
How do you check manual pump output with engine running?

[keithwahl]

Fuel phantom respons

how much supercharger boost pressure do you have when the car starves for fuel? Is the fuel pump to supercharger pressure line hooked up and clear?
Check manual pump output volume with the engine running.

with car floored i get 5# boost
i do not know pressure at starvation
fuel pump line to super charger is hooked up
have not pulled it off to see if clear
how do you check manual pump ooutput with engine running

[keithwahl]

Fuel phantom 2 electric fuel pump set up

Does everyone agree with the set up shown in the attached diagram for the electric fuel pump
i presume this diagram references a solenoid for the red line going to the manifold vacuum switch

thanks
keith

[studediesel]

Fuel pressure needs to increase as boost increases or the boost will decrease or stop the fuel flow.
To check fuel flow the easiest way is to disconnect the fuel line from the carb. and put a piece of fuel hose over it and run the hose into a clear bottle. 1 qt. or larger.
Start the engine (it should run on the fuel in the carb for a minute or so) The fuel pump should pump about a quart per minute. So a cup in 15 seconds or 2 cups in 30 seconds. may be a little more or less.
If your carb is in the little GH air box with the steel line it would be easier to disconnect at the pump and put a barbed fitting on the pump with a 3foot piece of hose to put in the bottle.
If fuel flow seems low you could also test it with the electric pump on.
Once some fuel gets in the bottle you can submerge the fuel line in the fuel and look for air bubbles in the fuel---would indicate a suction leak on the inlet side.
Just some thoughts---when you run the electric pump pressure is higher which slightly raises the fuel level in the fuel bowl. A leak on the inlet side will decrease flow.
Boost pressure can overcome pump pressure if the pump is not receiving boost pressure. As you start up a hill the engine need more fuel, both as volume and the air-fuel ratio.
The electric pump when not running could be causing a restriction for the mechanical pump.

[SScopelli]

It sounds like your mechanical pump is having a hard time drawing fuel through the electric pump.

I believe Brad's advise is going unnoticed. Mechanical fuel pumps can only draw fuel from a tank if the line is clear. I do not think any mechanical pump was designed to suck fuel through a restrictive electric pump.

Here is one "prpoper way" to combine the two pumps.



In this case the mechanical pump draw fuel in the normal path, unrestricted..

If the electric pump is active, the check valve will prevent back flow to the tank and force the fuel to the mechanical pump.

If you have the electric pump in-line, i.e., where the check valve is, You may have created the phantom..


On the right is the R1/2 fuel pump. I am guessing you have the much smaller fuel pump the GH had.
The diaphragm on the R pumps were bigger than the standard GH fuel pump.



Even the original R fuel pump has only one small input valve, and one small output valve.

The performance pumps uses two input valves and one output valve to help suck the fuel harder from the tank.