Now needs starter spray after a week or more not driven, every time.

[BigYella]

I have a 1976 with original c2 engine and 3 speed auto.
It has a new problem where it won't start after sitting more than a few days.
If I hit it with starter spray, it starts right up.
It has always started a little rough, but I have done some battery and cable work, plus replaced the starter. Of note I also replaced the fuel pump a few months ago.

Anyway, after sitting for more than a few days, it turns over and over but won't start. I can try turning it, flooring the pedal and turning, etc etc. If I remove the carburetor and hit it with even a little starter spray, it starts right up and runs fine. If I drive it later that day, starts fine. If I drive it the next day, fine.

Why does this happen? Does fuel settle out of the line over a few days and then can't get to the engine fast enough to start, even with depressing the gas all the way for a bit while attempting to start? Is it something about the mechanical fuel pump needing the engine turning faster than just the starter motor does?

Anyone else have this problem?
Thanks

 

[DirtDonk]

Or, all of the above. It’s a lot more common these days, with volatile summer fuels, coupled with ethanol of various percentages. Not to mention the engine could just be getting a little tired.
Starting immediately when you spray means that the ignition is good, the battery is good, the starter is good and all that stuff. So you got it nailed with the lack of fuel.
Do you have an open element air cleaner, or a factory air cleaner?
You could test the evaporation theory by covering the bowl vents and seeing if it’s still takes just a few days. If it lasts longer, then fuel is evaporating.
Couple that with modern crappy fuel pumps and it does take more to re-prime the pump and get it up to the carburetor.

 

[DirtDonk]

Oh, and I suppose that siphoning is always a possibility. Well in theory it is possible, I think it’s very difficult with the Ford carburetor.
You did say you still have the stock carburetor?

Did you replace the fuel pump for a reason other than this? Do you still have it?

 

[Broncobowsher]

Can't siphon. There is an air gap at the needle and seat.
Gasoline evaporates, fuel bowls dry up.
Just because it is a new fuel pump, it can still be bad and the check valves slowly bleed fuel. Or it was good and you sucked up rust and that is letting the check valves weep a little bit.
Do you have dual tanks? Try setting the selector valve in the middle. If that valve is still good it should block fuel from draining back into either tank.
Fuel pump with weak/dirty check valves will also be hard to prime at cranking speeds. Air leaks past them too fast. Fuel, being thicker than air, will pump fine.

Last carburated hobby car I had I kept a squeeze bottle with 2-stroke premix fuel in it. I knew a vacuum line I could pull off, give a squeeze of juice, hit the key and it would fire right up. Fixed that with an EFI conversion. And other cold start issues, and cold drivability issues.

Properly working choke and accelerator pump also matter.

 

[f2502011]

This behavior is very common today with current fuels and old tech. I would chalk it up as normal and not sweat it. Every vehicle I’ve had with one or more carbs has behaved this way over the last decade or so despite how well it was tuned or how new the components are.

 

[DirtDonk]

Since way, way back in time, when people had this issue or other similar issues with getting a fuel pump to prime, they either installed an electric fuel pump to fill the carb, or they use the electric fuel pump to push through the mechanical fuel pump.
That’s ok sometimes, but not always a good idea, though because if a fuel pump diaphragm fails, you don’t want your electric pump pushing gas into the engine.

 

[BigYella]

Can't siphon. There is an air gap at the needle and seat.
Gasoline evaporates, fuel bowls dry up.
Just because it is a new fuel pump, it can still be bad and the check valves slowly bleed fuel. Or it was good and you sucked up rust and that is letting the check valves weep a little bit.
Do you have dual tanks? Try setting the selector valve in the middle. If that valve is still good it should block fuel from draining back into either tank.
Fuel pump with weak/dirty check valves will also be hard to prime at cranking speeds. Air leaks past them too fast. Fuel, being thicker than air, will pump fine.

Last carburated hobby car I had I kept a squeeze bottle with 2-stroke premix fuel in it. I knew a vacuum line I could pull off, give a squeeze of juice, hit the key and it would fire right up. Fixed that with an EFI conversion. And other cold start issues, and cold drivability issues.

Properly working choke and accelerator pump also matter.

Nice, I like a low tech solution like that. I wonder if I could install some kind of primer pump like I have on my boat engine to save having to remove the carburetor - not that it takes that long, but would be nice.

 

[BigYella]

Oh, and I suppose that siphoning is always a possibility. Well in theory it is possible, I think it’s very difficult with the Ford carburetor.
You did say you still have the stock carburetor?

Did you replace the fuel pump for a reason other than this? Do you still have it?

Thanks for the input. I replaced the fuel pump because it failed-was weeping (heavily) fuel from weep hole (I guess bad diaphragm)

 

[BigYella]

Or, all of the above. It’s a lot more common these days, with volatile summer fuels, coupled with ethanol of various percentages. Not to mention the engine could just be getting a little tired.
Starting immediately when you spray means that the ignition is good, the battery is good, the starter is good and all that stuff. So you got it nailed with the lack of fuel.
Do you have an open element air cleaner, or a factory air cleaner?
You could test the evaporation theory by covering the bowl vents and seeing if it’s still takes just a few days. If it lasts longer, then fuel is evaporating.
Couple that with modern crappy fuel pumps and it does take more to re-prime the pump and get it up to the carburetor.

I guess factory because I don't know what an open element air cleaner is ha. I have the cylinder type that screws down on top with a wing nut.

 

[Broncobowsher]

The factory air filter sits on the passenger side of the engine and has a duct that comes out of the top of the filter housing, across to the top of the carb.
Sounds like you have an aftermarket air filter housing. Open element, just looking at the filter you are actually looking at the filter. You don't have to open the housing to see the filter.

Electric fuel pump will prime the carb. But nearly all of them you have to keep running. They are a restriction to the fuel flow if you try to use as just a primer. The Carter P4070 is well liked around here. Many having decades of service. Most are pretty quiet as well.

 

[chuckji]

I guess factory because I don't know what an open element air cleaner is ha. I have the cylinder type that screws down on top with a wing nut.

does it look something like one of these?

 

[ntsqd]

My '73 SBSS that I'm currently DDing is like that, have to crank it for a while almost every morning. Certainly every morning after a hot shut-down. Modern fuel is formulated to work best in EFI vehicles. Those of us still driving carbs suffer for it.

In the avatar I had an electric pump at the tank and a mechanical pump on the engine. I only ever used the electric pump when it had been sitting long enough to have an empty fuel bowl. The pump that I used was a Facet impulse type pump. I tested it to see if I was going to have to run it all of the time, or if I could pull fuel thru it when not operating. I'm not sure if that pump would flow enough fuel to feed a V8, running or not, but pumps that can be drawn thru do exist.

That said, If you're going to keep it carb'd I would go to an electric pump. The Carter P4070 mentioned above is an excellent pump to do this with. I would wire it with an oil pressure switch for safety. Even better would be to set up the fuel system with a by-passing regulator and a return line. The other bugaboo of modern fuel is that it vapor locks more easily than old fuel when not under some pressure. Put the regulator on the engine near the carb.

 

[Brush Hog]

If it’s an electric choke could be an issue with that since it’s only cold starts. I run a carb with electric choke and manual fuel pump. Knock on wood after sitting for weeks it will start within about 5 seconds of cranking. Warm starts with a bump of the key.

 

[Bruners4]

I don't know the details on the carb that you have installed but the Ford 2-barrel carbs were notorious for having the power valve diaphram on the bottom of the fuel bowl to leak. Engine vacuum is on the dry side of this diaphram and when leaking fuel, it goes directly into the intake manifold. Maybe something to check?