Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

Hard Start After Days

(1/2) > >>

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.

Navigation

[0] Message Index

[#] Next page