[Formulajones]

I'm restoring a 68 400 Firebird at the moment. It's been up on my lift for at least the last 2 weeks finishing up stuff.

I just removed the fuel line (from pump to carb) and it spewed at least a cup full of fuel after sitting all that time. Some out of the body of the pump and the rest came out of the fuel line itself. Seems normal.

Maybe a test if holding fuel is a question would be to crawl under the car after it has sat a while and crack open the fuel feed line at the pump, see if anything comes out.

That'll tell ya if you really have a drain back issue.

[MatthewKlein]

Originally Posted by Jon Salem

Parsival,

Didi you resolve the issue? I have a 71 Lemans Sport w/400/4BBL and after 3 days have to cracks and crank or throw some fuel down the throat. Runs fine otherwise. A mechanic mentioned a bas check valve.......Thanks.

When you experience the hard start remove the air cleaner, open the choke and look down the primary throttle bores. At the same time pump the throttle. You should see a steady stream of fuel from the accelerator pump. That's the first step I would take to diagnose your issue.

Edit:
Also, on a cold engine the choke should be closed. If the choke and high idle are not properly adjusted the engine will start hard and run poorly till warm.

[Jon Salem]

Originally Posted by MidnightAuto

Gas does evaporate fast. I put a check valve in and it did help in summer. I am still considering a pusher.

Looks like the pumps have two one-way valves. The manual has nice pictures. A simple test : run engine and let cool. Cover carb with clear plastic and plug canister hose. Let sit 3 days. Check plastic for vapor condensation. Remove plastic and plug. if the motor start quickly, then evaporation is the issue. If not, it must be running back to the tank....................The system seems sealed.....I can email the pictures and text - they are a bit large to upload.

[Jon Salem]

Thanks. Make sense. Looks like the pumps have two one-way valves. The manual has nice pictures. A simple test I may try : run engine and let cool. Cover carb with clear plastic and plug canister hose. Let sit 3 days. Check plastic for vapor condensation. Remove plastic and plug. if the motor start quickly, then evaporation is the issue. If not, it must be running back to the tank....................The system seems sealed.....I can email the pictures and text - they are a bit large to upload.