Hard Start After Days

[Chevynation]

Hello, I have a hard start condition after a few days on my quadrajet (7040203). My fuel is evaporating or draining back to the tank. I have a main fuel line and a return fuel line going to the fuel filter and the return line goes back to the tank. My mechanical pump doesn’t drain back on my other vehicles but I don’t have a fuel return line on those either so maybe it’s draining through that line, not sure. I posted a picture but it’s not my car but same setup as far as the fuel line setup for the most part. I have to crank 3 or 4 cycles to get the engine to fire up. I know the filters with the check valve are restrictive but is there anything that can be done to correct this besides having an electric fuel pump? If the clip on the needle valve was removed would that make a difference being that the fuel wouldn’t drain below that point anyway? The car sits pretty much the entire winter.

https://ibb.co/xXz6fcm

[Chevynation]

My fuel pump doesn’t have the check valve. Can I install a check valve between the tank and the pump or does it have to go between the pump and the carb?

[Chevynation]

Another thought that I had was to see what seat I have because a windowed seat could also cause fuel to drain as well correct? I’m not sure if the windowed seat performs any better besides having multiple paths for fuel to enter the bowl.

[quadrajam]

This modern fuel is not friendly to a Q-Jet carburetor. The fuel bowl only holds
about 70 mL of fuel and most of it will evaporate in a day or two. It only has
to drop a little bit to render the accellerator pump useless and you wont crank
without a couple of squirts from it.
 
Adding a check valve as you mentioned may help in that the whole line and pump
 wouldnt drain back and you would only have to fill a half dry fuel bowl.

I have been fighting this same fight for a while and am going to convert to an in tank
pump with a bypass regulator under the hood with return line.

[Chevynation]

Thanks. I’ll remove the clip from the needle tomorrrow so at least the fuel can’t drain back. Can’t do anything about evaporation so that’s fine.

[77cruiser]

I put in an in tank pump several years ago. Only way to IMO.

[Chevynation]

Yeah I’ll have to invest in that setup. I took the air horn off to only realize I already don’t have the clip on the needle. No big deal.

[Kenth]

Clip is there for a reason.
If everything else is failing, follow the manual.

[bob69]

I have two 1969 chevys with the external (ac gf432) filters. I found that blocking the fuel return line will allow the float bowl to fill quicker.

The fuel does evaporate from the float bowl in a few days. I do not drive the cars every day. Sometime not for months. It takes a lot of cranking to get the fuel bowls to fill.

During one of my test and tune sessions, I replaced the external fuel filter with a straight through line. The fuel bowl filled quicker. Filled in 4 -5 cranks instead the 5 to 10 seconds of cranking.

The fuel in the filter was draining back to the tank. Especially when the engine had been heat soaked. This new fuel expands a lot when subjected to heat. The fuel in the filter expands and returns to the gas tank. Very little fuel is left in the filter which causes the long cranking times.

I've been dealing with this fuel problem for a long time. I started filling the fuel bowl before starting an engine that sat for a week or more. Took a clear plastic water bottle and made a mark with the right amount of fuel to fill the bowl. Fill through the top vent. Use a fitting from a rtv tube with the end cut off.

Pump the gas peddle to set the choke. The engine would fire up as soon as I turned the key.