yeahbuddy

Recently I changed my fuel pump and got rid of a vacuum leak issue in my 68 Cutlass Supreme with 350 Rocket. I can say my car is running the smoothest its been since I bought it a couple years ago. I am having an issue after starting the car after its been driven. I make a 10 mile drive to work everyday. I have an Edelbrock 650 cfm w electric choke. In the morning the car fires up with no issues on higher rpm until I tap the gas. My problem is once I park for about 3 hours and return to go to lunch...the car starts but will quickly die unless i hold down the gas pedal. It drops below 500rpm. I usually hold the gas down and put it in drive and accelerate down the street. That is usually enough to get it to stay idling around 700-800rpm with no issues. In confused why this is happening? Its been doing this before the fuel pump was swapped. I do experience heat soak ad well if i try to start the car 15-20 min after a drive. Cranks slow but fires up. Overall i have no issues with the car driving...just after a drive it doesnt handle starting up and idling in park well once sitting. Something different i have noticed also is my volt meter usually holds at 14v but sometimes will bounce around 12v when idling on start up. Once i gas it up the street it to climbs to 14v and stays there. Any ideas? I fiddled with the two adjustment screws on the carb but it didnt help .

MDchanic

Sounds like your fast idle isn't high enough.

3 hours is enough time for the engine to cool down and for you to need the choke again, but when you step on the gas and set the choke, the ide is too low.

Of course, with a low idle, the alternator isn't turning very fast, and the voltage will be low.

- Eric

oldcutlass

Are you resetting the choke, after 3 hours you may have to pump it once and then start it. Are you using a stock fuel pump replacement or a high pressure?

yeahbuddy

I usually don't reset the choke when I start it up. It gets to around 75-80 here in California by the time I drive it for the second time in the day.

I called all the local parts stores about the fuel pump and the only thing I could find was a stock style from Kragen. To be honest, my car was giving this really bad hesitation when I would accelerate heavily to 40-50mph almost as if it wasn't getting enough fuel. I thought it was mainly transmission related but I notice that that hesitation stopped almost completely. There are some moments when it will do something similar which is making me think that maybe it isnt feeding the 650cfm carb efficiently when accelerating heavy?

MDchanic

We need to know clearly whether this is a cold-running problem or not.

If it only has the hesitation / low RPM when it's cold, then it's because you're not setting the choke.
Just because YOU feel warm doesn't mean that the engine is warmed up. IT doesn't feel warm until it's about 160°, well above the 80-90° that make you feel cozy.

If the hesitation occurs regardless of temperature or run time, then you should consider the fuel pump, especially if it is worse the faster you go, and if rather than bogging when you first press in the pedal, it starts out well, then "runs out of gas" after a few seconds.

Also, do you have the exhaust ports in your intake manifold blocked off? If so, it will definitely need more choke for a longer time in warmer weather.

- Eric

oldcutlass

If the hesitation is occuring always when trying to accelerate then I would look towards the accelerator pump on the carb. Since you've replaced the fuel pump, did you also reset your a/f and choke settings? Also I've found that alot of carburetor issues are actuallly ignition problems. Make sure your distributor is set correctly.

yeahbuddy

The hesitation and idle are two different issues. I was responding to the question about the stock or high perf fuel pump.

My temp gauge is around 140-160f degrees when I start it up for the second time of the day. The issue only occurs once I've driven the car for a distance and park it for 2+ hours. When the car is started for the second time of the day after cooling off...it starts but quickly drops RPM and dies. I have to lightly press the pedal to keep it running or once I drive up the street it starts to idle fine on its own. I can record a video today showing the second start up of the day to give a better idea.

MDchanic

You need to adjust your choke closed just a hair, so that the first step of the fast idle is just engaged under those conditions.

- Eric

yeahbuddy

Is that done directly adjusting the two screws? Clockwise or counter clockwise?

MDchanic

Those are idle mixture screws, and have nothing to do with your idle speed, fast idle speed, or choke setting.

I am now beginning to wonder whether the other carb. settings are correct, or whether they could have been changed, leading to this problem.

I am most familiar with Rochester carbs (2-Jet and QuadraJet), but I believe I can picture the settings of the AFB / Edelbrock well enough to provide some guidance.

The choke should be a round black plastic part about 2" in diameter on the side of the carb, held on with three screws, with a wire coming from the middle.
Look at the carb to see where the fast idle cam is, and how it's adjusted. The fast idle screw will be resting on the cam. If you hold the throttle open and move the choke open and closed, you will see the cam move, with the screw positioned over higher steps as the choke closes.

Drive the car the way you normally would and park. Take off the air cleaner and look to make sure that the choke is fully open when the car is fully warmed up. Put the air cleaner back on.
Now leave the car for the amount of time that usually causes this problem. Go out and remove the air cleaner again and give the throttle a blip. Look at the choke plate - is it wide open, or is it just a little bit closed?
Loosen the three choke adjustment screws a bit.
Hold the throttle open slightly, so that the fast idle screw is off of the cam.
Turn the choke adjustment very slightly toward the "Rich" direction, until the fast idle screw is just barely over the first step of the cam, then retighten the screws.
Put it back together and try driving it again.
If the problem has gone away, check it once more when it is fully warmed up to be sure the choke is still 100% open while warm.

- Eric

oldcutlass

Let me just add a little more info, on the Edelbrock, the choke adjustment screws are torx head. There are 2 wires on it, a red and black. First make sure the red one has 12v with the key in the on position. If it does not don't adjust anything yet. Once you get 12v on there see if it operates correctly before adjusting anything.

The adjustment that Eric mentioned on the choke is correct. To gain access to the idle speed adjustment for the choke, you have to move throttle linkage to the fully floored position and you will see the adjustment screw. You can manually engage the choke, and set that screw on the highest cam for about 1200-1500 rpm, on the lowest cam setting set it to 900 rpm.