I just replaced the gasket and oil pan on my SBC. It was running a week and a half ago when I put up on ramps to do the pan change. It has a newly Lars-rebuilt Quadrajet on it that is only about month-and-a-half old. The engine has always been hard starting when cold, takes at least 3 turns of the key of about 10 seconds each. The new carb runs great once it started and would fire right back up when warm, but when cold it is still temperamental. This situation is new, seems to have fuel, or least fuel shoots out when the accelerator pump is operated. There is power to the coil.
One thing, the fuel tank is somewhat low, I'm not sure if being on ramps will cause it suck air. Where is the fuel pick up in the tank? Is it toward the front? I tried to add 3/4 of a gallon, but still nothing. Should I try to take it off the ramps to get fuel to the pump?

 

If fuel squirts in the carb, then I'd say it's not a positional issue with the fuel tank and pick up.
You have an energized coil, but do you have spark at the plugs? There are simple, inexpensive spark testers available from auto parts stores.

 

This will get it going when cold. And yes, put the car on level ground.

 

How old is the Ignition coil? Is your ignition coil a round can or the newer square ones? How about the Spark Plug wires, how old and what is their condition? I would want to see it "spark" before going on further. Coils and Wires have been a problem for my C3 in the past couple of years. The quality is just not there any more. The solution from MSD, "Just buy a More Expensive Square shaped Blaster 2 coil that is sealed in Epoxy" versus a can of oil.

If the fuel level is low and you have the car on a lift, have you seen or noticed any water in the gasoline? Smell the fuel coming out of the accelerator pumps to be sure it is indeed gasoline and not watered down gasoline or even plain water. I would try it on good supply of good gasoline. Maybe a five gallon jug and a rubber fuel line from the "pickup" on the mechanical pump to the fuel can is able to reach. This would bypass your C3's fuel system on the chassis and see if the fuel works better. If you have water in the tank then you simply drain the tank and start over. If you have a dirty fuel filter this also can slow down the fuel and make problems.

Once I was getting ready for a day trip and I saw a small puddle trying to form under my C3. It was a gas line leak that started life as a Pinhole in the fuel line. I wrapped it in a small sheet of rubber and put a hose clamp on it. The problem would have shown up as a lack of fuel because AIR was being sucked into the tiny pinhole. I would check the system from rear forward to ensure that the fuel lines are still good. Any rubber that predates Oxygenated gasoline needs to be replaced with the newer blends of rubber that are Ethanol resistant. I am also referring to all the vacuum lines as they are dry rotting and need to be replaced to ensure the best performance

Are you using Oxygenated gasoline? How much percentage of Ethanol is the fuel you are using. How old is the gasoline inside the tank? While looking in the fuel tank do you see any water or a stratified level in the fuel tank? After a while the water builds up in the fuel tank as Ethanol is Hygroscopic and absorbs water just like brake fluid does. If you get enough water in the fuel tank and eventually it will get into your fuel system.

I had a C4 crank and not run until I learned it had rusted up the fuel Supply line inside the tubing. The gas was getting there under pressure but not enough volume for the engine to run on. I put a fuel pressure gauge on it and it was right on. The flow was restricted and that was not obvious until I measure the actual flow rate. Once the fuel flow was back to normal the engine ran fine.

What about the battery you are using to crank this engine. How old is it and what is the normal open circuit voltage on it if you checked it recently?

I will be watching for your answers, we will get you back on the road again, soon!

 

I suspect you're not setting the choke correctly if you're having cold starting problems. If it starts and runs fine once the engine is warm. Do you need to feather the throttle once the engine starts when cold?

 

It definitely does sound like a choke issue . When cold and before stating engine , remove air cleaner , press throttle once , this should set the choke closed . If it doesn`t you will need to find out why . If it dose then you will need to make sure that fast idle cam is being set . In other words you need to do a complete choke system check and adjustment . You can find how in your repair manual .
Steven

 

You said Lars just rebuilt it a month ago. Contact Lars to explain the problem you are having. .

Post pictures of the choke side of the carb and from the top after you set the choke. After his rebuild you should not be having any problems with the carburetor.

 

I picked up a spark tester today and will give it a try tomorrow. There is a very strong smell of unburned fuel after cranking it a time or two for about 15 seconds each time.I'll report back what I find. Thanks for the help!

 

I can't say how old any of it is! I bought it from my dad two-and-a-half years ago, he's older so I'm not sure he even knows when anything was changed. It has an Accel points eliminator and coil in there now.
Like I said, it was running well enough a week and a half ago before I put it on the ramps and changed the oil pan, gasket, oil and oil filter. Except for the start-up, but at least it was starting eventually.

I don't believe the gas is too old, I have added more and lowered the car off the ramps. I tried to start it after that, but still nothing. I will try again tomorrow. I might try to unscrew the carb fuel inlet to see if that will allow fuel to flow into the pump. I also replaced the rubber fuel lines to the pump about a month ago, so hopefully those are good..
Battery is good, only about a year old and cranks hard. I will try the spark tester tomorrow also and report back.
Thanks for the help!

 

Sometimes it would die after running for 15-20 seconds. After it starts again, then yes, I would need to feather the throttle to keep it RPMs up, though only for less than a minute, then it would idle at low RPMs without help.

See photos below

I was planning to contact him about the hard starting, but it wasn't anything needed immediate attention as the engine was still starting at that time. Now I just want to figure out why it isn't starting at all.

None of the divorced choke components were included with the carb, I purchased the carb off eBay and had it sent directly to Lars. Then after receiving the carb I purchased the divorced choke parts. Of course Lars had it running perfectly, but I don't know what he used for a choke or if he even needed to.

I have wondered if the choke has been problem. Although it was a little tough to start even before I switched to the Q-jet (had an old Edelbrock on it before) it has been a little more difficult since. But now it won't even attempt to fire.
Here is the choke as I have it set up, this is after one press of the accelerator. I never found any good pictures of the '73 set up so I just pieced it together from what I could find and what looks correct.




I did notice after cranking that the choke plate slightly opens, but I think it did that before putting it on the ramps to change the oil pan.
Any further ideas would be greatly appreciated!!!
Thanks to all!

 

You might want to verify that the rubber fuel hoses you replaced between the steel line from the tank to the fuel pump are not kinked.
Easy to do especially if you don't use the pre molded hoses.
A kinked hose would severely restrict fuel delivery to the carb.

 

You flooded the engine. Raw gas in the cylinders. Spark plugs are soaking wet and won't ignite,

 

I did use the pre-molded hoses, but I'll double check. They might have been twisted slightly when installing them. Even though I clamped the hoses, fuel was still coming out so I was rushing a little.

 

How to start a vette the proper way

 

I had that thought, too. The first time I tried to start it, after the oil pan/gasket change, my 20 y.o son tried to start it. I gave him instructions to only press the accelerator a few times, but he ended up continually pressing it before I noticed.
If it did flood, wouldn't the fuel evaporate overnight? Or do I need to remove the plugs and check them?

 

Yep, that's the way I've done it and it will usually start after 2 or 3 times, but after being on the ramps it's a no go. Of course my son didn't follow my instructions, so it probably did flood the engine.

Interestingly, the 'Related Post' that followed the post you linked above, was talking about a weak fuel pump. Like so many other things on this car, I have no idea how old it might be. Could that be a culprit for all the hard starting issues?

 

If it was my car, I would try to start the engine using the starting fluid. I'm betting it will start and run.

 

Evaporating a flooding situation from an engine by just letting it sit would be a pretty long wait given how closed most of it is to air circulation. To clear a minor flood, you would hold the gas pedal to the floor and crank the engine for ~20 seconds, let the starter rest/cool for ~30-40 seconds, repeat 1 or 2 more times but don't let the pedal up. This sort of cranking with full air flow (pedal to the floor) encourages air circulation and evaporation.

A major flooding incidence is best cleared by pulling the plugs and cranking like above. Before reinstalling the plugs, blow off with compressed air if they seem fuel soaked. You can also burn off the fuel with a propane or butane torch pretty quickly.

After trying the cranking process above, release the pedal from the floor and try starting with no pedal. Most engines don't need much fuel to kick over - a couple tablespoons should be more than enough. If the engine doesn't start after ~10 seconds of cranking, press the pedal 2 times and let go (this assumes the jets are squirting fuel). Crank again. Repeat once more but if still no start give it a couple spays of starting fluid.

At some point near the end of this process, you should be getting some sputters and signs of the engine kicking over. If not, then I'd be investigating other possibilities than just flooding.

 

Sorry for the delayed response. Thank you for all the help so far!
I finally got around to trying the spark tester, the cord is not very long and from the driver's door, I can't see it directly. the first time I used it there a appeared to be a few very bright flashes from the area where the tester was laying near the alternator. I wasn't expecting it to be so bright and thought there were electrical sparks coming from other wiring and stopped cranking immediately.
However, the next time I used it I could just barely see it and there was nothing.
Two questions: Did the tester work the first time? And did it burn out the bulb and not work the second time? Thinking it might have burned out, I attached my timing light to see if it would flash as I was cranking, but there was nothing, nor any indication of RPMs on the readout. It should flash if there was signal through the spark plug wires, right? Even when cranking.
I pulled all the spark plugs and there was evidence the engine was flooded, but interestingly it appeared most noticeable only the right side bank (even numbered cylinders). I dried and made sure they were all clean, then cranked the engine repeatedly over the course of a few hours to dry the cylinders.
Still nothing.
It has an Accel points eliminator system in it. Is there a way to check if it is still functional? Should I replace it with points and condenser? Or I've even tossed around the idea of getting an HEI set up? Thoughts?
Thanks again for all the help!

 

Do you have spark, when the plugs were out you could have grounded one and cranked the engine to verify.. If so have you tried starting fluid... Two simple things that will give a lot of answers...

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