Late last summer my car suddenly became difficult to start when the engine was cold. Normally it would fire right off and run great even after sitting a week or so.

Now when cold, after sitting overnight, I need to crank it for about 10-15 seconds, then it will fire, run rough for 30 seconds or so then smooth out.

I have 2 different carbs and it acts the same with either. Both are Edelbrocks (I've had good luck with them). I'm not sure how to tell if there is fuel in the bowls after sitting overnight. Both electric choke style, chokes seem to work fine.

GM HEI, newer plugs and wires, Pontiac 400.

I'm stumped, but then I am not very good with this sort of thing. Thanks for any suggestions anyone has.

How do the plugs look?

Hi Mike

All are dry, color good.

That's common with leaking well plugs or fuel percolation, but those are not typically issues with the Edelbrock carbs. How old is the gas in the tank? Add some fresh fuel if the gas in the tank is more than three months old.

Fifteen minutes after you stop the engine, remove the air cleaner lid and sniff for gasoline vapors. If there is a strong smell of gas in the carb throat, your carb may be leaking down into the intake. Also check for gas seeping from the inlet or filter, or at the pressure side of the fuel pump.

After an hour, lift off the air cleaner and open the throttle. See if the accelerator pump gives a shot of fuel into the primary bores.

Does your fuel pump have a return line, is it a stock pump, and is the return line connected to the sending unit?

You can test for an empty bowl issue by using a bottle (like a nasal spray bottle) to shoot about a teaspoon of gas into the carb to simulate an accelerator pump shot. A quick blast of starting fluid will work too. If the engine starts immediately, look for fuel issues.

Thanks Vikki, I will try those things. The pump is a stock unit with a return line, I believe it to be hooked up correctly.