i have a 91 firebird tbi that i swapped to 350 carb.im running vortec heads 9.5 compression,medium cam,in tank fuel pump with mallory return style regulator.stock feul lines even the stainless hard lines along the manifold.the car will start on a dime when cold but when i kill it,it wont start again.turns over maby a slight carb backfire or two but just wont start.let cool a couple hours and it will start up.ive been hearing the fuel lines along the manifold are getting hot in turn getting the fuel hot.but what i dont understand is that i have a return line so the fuel is constantly getting circulated back to the tank seeming to get some fresh cool fuel.i could be wrong though.are the lines getting hot enough to heat up the fuel that fast and then once it gets into the hot carb it starts expanding?ive tried running with and without a 1" alluminum spacer.no difference.also i need to get my car out of my buddies yard and drive it 12 miles and then it can set till i can fix the problem.will it die when it gets hot or as long as i keep it running will i be ok?

 

please help

 

Get fuel pressure readings under these conditions.

 

you have a similar setup (at least fuel wise) as I do. Mine did this exact thing.

Check a few things:

1. Timing - start your base timing at 12 and see if that helps it start
2. Check the fuel pressure, for a carb i believe its about 6 psi.
3. Make sure your starter is in decent shape. Heat and high base timing can cause alot of headache to the starter. Also make sure your battery is high enough cranking amps. My old one was 400 and some, I bought one that has over 600 and it turns over on a dime now (after that and timing fixes)

Hope you get her runnin!

 

This is from the FWIW department regarding phantom vapor lock problems - after trying everything on the '84 to try to fix a similar problem (cap, rotor, coil, fuel pump, rerouting lines, yada, yada, yada), the problem turned out to be a bad TCC solenoid that was keeping the converter locked up. Once the car cooled down enough the TCC released and the car started right up. I just unplugged the connector at the transmission and did'nt have any more "vapor lock".

 

thats gotta be one of the strangest things I've heard but makes sense it could do that. Wild

 

Second this.

Do you have any sort of pressure regulator in the system? A stock TBI pump is like 10-14psi, it might be flooding out...