Fuel delivery issues 41 Chevy

[Porsche 68]

Rebuilt fuel pump 1/2 tank of gas blew compressed air through fuel line no blockage just can’t get fuel to the pump Bench tested pump with a fuel source attached works great still nothing from tank Has 3 inches of vacuum at pump with a gauge attached is 3 inches enough? Ready to push outside and set on 🔥.   Just kidding john

[Dave39MD]

It takes a lot longer than you think is correct to get the fuel to the carb using the starter. You might try adding a little fuel to the carb if you feel safe doing so to get it to fire and turn the pump at a higher revolution.

 

Dave

[kramaton]

Could possibly be sucking air on the line somewhere. If you are the pump will never draw gas. Check your hoses and connctions.

[Oldtech]

Can you put a bit of pressure to the tank and see if fuel comes out the line by the pump, or anywhere else? a pinhole in the line can mess your day.   So can a pickup tube with a problem inside the tank. 

[Bloo]

2 hours ago, Porsche 68 said:

is 3 inches enough

No. Well maybe, teed or dead headed? If you are teed, low is good, high indicates a restricted line or pickup. With the gauge dead headed on the inlet it ought to suck up a lot more than that. I don't know how much exactly, but a lot more than that.

[WPVT]

Pump the accelerator with the air cleaner off, and watch and listen for the sound of the accelerator pump squirting fuel. If it doesn't squirt, that means the carburetor fuel bowl is empty.  If that is the case, you can start the engine with starter fluid. If it starts and runs, then your problem is that the fuel pump won't fill the carburetor at starter speed, but it will at engine running speed. If you stop the engine, and it restarts easily, that's because the carburetor bowl still has fuel in it. 

This procedure doesn't determine whether the problem is a weak pump or an air leak, but it will establish that the problem is no delivery at starter speed.

I have more than one vehicle that needs some help if it's been sitting and the bowl goes dry, even with a rebuilt pump. Sometimes starter speed just doesn't seem to be adequate for fuel delivery. 

 

[Grimy]

The first thing I'd check or replace is the flex line between the fuel pump and the hard line from the tank.  Those rot from the inside out, can suck air without leaking fuel, or can deteriorate on the inside so that a "flap" of lining blocks fuel flow.

[Rusty_OToole]

I have a circle of rubber cut from an old inner tube with the valve in the middle. I can put it on the fuel tank filler with a hose clamp and pressurize it slightly with an air hose. This always gets the fuel going. You only need a couple of pounds of pressure, enough to bulge the rubber slightly.

[Joseph P. Indusi]

I agree that just running the starter may not be enough to start the engine easily.   If I do not use my Buick for about a month it will eventually start off just the starter but it can drain the battery and worse overwork the starter.

So, I drilled a tiny hole in the air cleaner intake near the carburetor air horn and then I insert the red plastic tube from a can of Walmart carburetor cleaner and give a squirt with the choke and throttle wide open.   Then I get in and try to start the engine.  Usually, may take two squirts but it always starts.

Caution:  Do not use starter fluid as it is very volatile and may cause damage.   If you don't want to use carb cleaner, then just inject some gasoline into the carburetor.

However, the posts above offer some issues that you need to check out such as an air leak somewhere between tank and pump.

Joe, BCA 33493

[Porsche 68]

Ok out in the garage I primed the fuel pump and started the car Hooked the car’s fuel tank an ran the car 1/2 hour Then I thought about it I put everything back together the way the pump came off the engine is the pump upside down shouldn’t the glass bowl be on the bottom?

[Oldtech]

Nope. That is the correct way.  Wierd I know. 

[Porsche 68]

Also I rebuilt the carburetor it’s fine runs smoothly Like I said in the previous post the fuel pump has 3inches of vacuum at the pump head Old Tech I had a 54 Chevy the pump was on the other way round That’s what got me thinking. John

[Oldtech]

Ya, they had both types and one with no glass, just a can. All fit the same engine. The internal arm on the cam has to go up. That's what matters. 

[Frank DuVal]

On 12/4/2023 at 9:05 PM, Bloo said:

With the gauge dead headed on the inlet it ought to suck up a lot more than that. I don't know how much exactly, but a lot more than that.

It should do whatever the barometric pressure is at your location that day! i.e. it should get close to perfect vacuum on a 0-30 inch scale. If it cannot, the internal check valves or diaphragm may be leaking. The force from the input lever pushes on the diaphragm to make suction. So it should go to maximum vacuum (barometric pressure).Pressure for output comes from the internal spring only. Now for this dead head test the outlet needs to be open, so the spring will return diaphragm to bottom of stroke.

 

I agree with putting a rag into the fuel fill opening and then stick an air blower in there to pressurize the tank with a few psi. I've done that on stubborn cars where I replaced parts of the fuel system. Don't drop the blower into the tank!😮 Oh, rubber disc is even better.

 

Glad it is running now!👍

 

 

🦃 🦃 🐖 🍠🥔🎄 🕎 ❄️

 

Edited December 6, 2023 by Frank DuVal (see edit history)