fuel bleeds back

i have a 73 monte with a q-jet the problem is it is hard to start...the fuel will bleed back to the tank...i drill and rebuild my own carbs. the plug at bottom of carb not leaking and i have also replaced the filter in carb,cap,fuel pump and have even changed the carb with another q-jet same thing.it will turn over 1-2 mins. then start and when it starts it will run and start fine after untell it sits over night...any help thanks

scott

fuel pump?

I HAVE PLACED THE FUEL PUMP ...YOU THINK IT COULD BE BAD AGAIN?

BUT I WILL TRY IT AT THIS POINT.THANKS  SCOTT

This sounds like the fuel is being boiled out of the carb when it's allowed to sit after running on warm engine. You should have an insulating spacer between the manifold and the carb to keep the hot intake from soaking heat into the body of the carb.

Bogie

IT  HAS NOTHING TO DO WHEN IT IS HOT IT RUNS AND STARTS FINE .IT ONLY DOES IT AFTER SITTING OVER NIGHT NOT HOT..........

SCOTT

What did you use to seal up the plugs on the bottom of the bowl? I found out my jb weld kinda went bad after a few years. Dont talk too descriptive about this to anyone this is the worlds best kept seacret.There are tons of Q jets they are scrapped after acting the same after a kit.I even heard people say they did THE KIT TWICE AND STILL ACTED THE SAME.  

yeah that's what I told ya, you need to think about the time effect while the carb sits on top of a hot engine that's transferring heat into the carb without the fuel pump replenising what's evaporating. It's a matter of how fast the evaporation rate occurs. The only other answer is the carb is leaking fuel out the bottom of the bowl, something qjets are noted for. Fuel cannot leak back through the pump to the tank as the needle valve is not submerged, therefore a syphon cannot form.

The other choice you have is the fuel pump's crapping out and neither keeps the fuel up to the proper level in the float bowl, or does allow pressure to bleed off to the tank as the car sits unrunning and the heat cooks the fuel out, therefore there's no residule pressure to dribble fuel into the bowl as the level drops, or the pump just can't provide adaquate fuel while cranking to fill the bowl. But since this was already covered, I thought I provide some insight that hadn't been already given you.

Bogie

THANKS I WILL TRY THE FUEL PUMP FIRST AND SEE WHAT HAPPENS.

SCOTT