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Carb Starting Problems

Ed Martin

Ed Martin

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I just installed a new Holley 80457SA 600 cfm carburetor with electric choke on a stock 68 Roadrunner 383 manifold. When starting I have to crank and crank while trying different things with the pedal. First I pump it once to the floor and let up before turning the key. But it just cranks, so I pump again thinking it needs more fuel and it still won't start. Finally it starts after pumping a couple more times with the throttle at different positions (including wide open). I don't know if it's getting too much fuel or not enough. The accelerator pump seems to squirting fuel when checking under the hood and choke sets closed.

So how many times should I have to press the pedal at say 55 degrees ambient? This is very concerning with a new carburetor straight out of the box.

Please let me know what you think.
 
On initial install, the fuel pump has to fill the bowl. You don't do " different things" with the pedal. Did you set up the carb ? Fuel bowl level ? the choke & linkage ?
 
Thanks for your reply.
I didn't see anything in the instructions about doing these things. You mean the choke linkage? Isn't the choke closure setting (amount open) fixed?
 
Curious what was the reason for the new carb? Reason I ask is did the old one work alright-good starting and your change over was for better giddeeup? (If you had problems before there could be more to check out) As WileERobby said a new carb has to get fueled up and since you're getting squirting seems like it's getting fuel at least some assuming you see a healthy squirt thrust. If getting too much fuel or flooding you should be smelling gas. If you can get the motor running, run it for several minutes for ample fueling and check the choke action by a slight popping of the throttle should be no need to open secondary's. Choke should then set to warmer idle setting if it's adjusted...they are often set from factory; but never a guarantee of proper setting. While on this note, (ask me how I know) ensure your throttle plates are opening all the way...no binding or contact with manifold or spacer if you have one. Also double check your sealing of the carb to manifold (no vac leaking going on from the install). Ok, tossed over a bucket of stuff but checks that can be made anyway...
 
On my car, I have to pump the pedal about 5-7 times before it starts (cold). After it's warmed up, I only pump the gas maybe once & it starts.
 
PurpleBeeper:
You mean pump it 5-7 times before you crank it? That sounds like a lot of fuel ... does the bowl hold that much?
 
PurpleBeeper said:
On my car, I have to pump the pedal about 5-7 times before it starts (cold). After it's warmed up, I only pump the gas maybe once & it starts.
Click to expand...
Wow that's a lot ! On a cold winter day, even after sitting for a few weeks 3 pumps and the turn of the key will give me fire !
 
Could be overchoking. Check you have 12 volts at the choke in the run position of the key. With key on and no cranking, as a test, you should see the choke opening to verify that it is coming off. Mopars are the best for starting when cold. When hot its a different story.
 
Ron H:
Thanks for that bucket of stuff! I have only started it twice with the new carb so I'm still trying to nail down the symptoms. On the initial startup I filled the bowl with fuel using a squirt bottle through the vent (only for the first time starting). Maybe that wasn't enough, but used about the same amount of fuel I had used on the old carb, since I don't drive it very often and the old one leaked down dry after couple of weeks (that was one reason I replaced the old carb - about 30 years old). The choke/fast idle cam seems to be ok after starting and idle speed comes down quickly to about 1000 rpm (maybe too quickly). Really the only problems with the old carb was the leaking down dry (and having to manually filling the bowl each (2 week) startup and I had trouble getting the fast idle down by adjusting the fast idle cam set screw or rotating the black choke cap.
 
Was the old carb visually leaking? I ask because it's not uncommon for the fuel to evaporate out of the bowls with today's fuels. One thing I've learned over the years is no 2 engines start the same you just need to play with them until you figure it out. My last car needed a lot of choke to fire, my current car doesn't even have a choke and starts easily every time? On a cold start with no choke 2 pumps, after warmed up I don't even touch the pedal.

I'd start with getting the carb tuned, check your float level, adjust the idle mixture screws then play with the choke.. all of this of coarse after you confirm everything on the ignition side is good to go. All of the carbs I bought new came with at least a basic setup procedure but if not I'm sure the guys here at FBBO will step up and guide you through it. Good luck
 
I put on an eddie carb with electric choke and only futzing was adjusting the choke to bring the fast idle down as it was up there too high I thought from a bone cold start near 1500 rpm. Reset to around 1100. After about a minute I can kick it down to mid-setting running around 7-800 rpm-ish. Old school nerves running a cold motor at high rpm I guess and mine has solid lifters now. Mine will start cold after I drop the pedal once about half way down to set choke. Yeah once you're comfy that carb and linkage is set right, you're getting fuel, you likely know some other checks with spark and timing to rule out of the mix.
 
I would start with checking choke while cold, before starting. Barely crack throttle & watch for choke to close.Then try 1 full pump, close throttle, hit the key; nothing(?) maybe go a 1/2pump. Shouldn’t take more than 2 pumps at the most at 55*. As soon as it starts, the choke plate should open automatically about 1/4” to allow enuf air to continue running. I don’t ever remember 3pumps except when Really cold( +10. or lower)
 
I would check the jetting on the carb. It is bound to have fairly small jets.
A 600 is a fairly small carb.
 
Just a suggestion, if you're using the car every couple of weeks, and not on a regular basis. Install an electric pump that will fill your carb with fuel after sitting a week or so. I did the tanks Inc. fuel pump and now after a couple of weeks sitting, run the pump before cranking and my Gen 2 Hemi starts right up.
 
747mopar said:
Was the old carb visually leaking? I ask because it's not uncommon for the fuel to evaporate out of the bowls with today's fuels. One thing I've learned over the years is no 2 engines start the same you just need to play with them until you figure it out. My last car needed a lot of choke to fire, my current car doesn't even have a choke and starts easily every time? On a cold start with no choke 2 pumps, after warmed up I don't even touch the pedal.

I'd start with getting the carb tuned, check your float level, adjust the idle mixture screws then play with the choke.. all of this of coarse after you confirm everything on the ignition side is good to go. All of the carbs I bought new came with at least a basic setup procedure but if not I'm sure the guys here at FBBO will step up and guide you through it. Good luck
Click to expand...
 
Thanks 747mopar. I could not see any external leaking with the old carb. I figured it was evaporating out the bowl vents or possibly an internal leak. It seemed to get worse about the time I started using ethanol-free fuel (a couple years ago). Before that, I could go three weeks and still had enough fuel to start it. I'm still using ethanol-free fuel, but at this point, don't have any reason to think the new carb is not holding fuel. I wonder what the volume of fuel the accelerator pump puts out is compared to the volume of a full bowl? I will have to look again at the instructions that came with it, but don't remember that much was needed to set it up or at least anything related to how to fire it up when starting ... maybe, like you say, because no two engines start the same.
 
Ed Martin said:
Thanks 747mopar. I could not see any external leaking with the old carb. I figured it was evaporating out the bowl vents or possibly an internal leak. It seemed to get worse about the time I started using ethanol-free fuel (a couple years ago). Before that, I could go three weeks and still had enough fuel to start it. I'm still using ethanol-free fuel, but at this point, don't have any reason to think the new carb is not holding fuel. I wonder what the volume of fuel the accelerator pump puts out is compared to the volume of a full bowl? I will have to look again at the instructions that came with it, but don't remember that much was needed to set it up or at least anything related to how to fire it up when starting ... maybe, like you say, because no two engines start the same.
Click to expand...
The volume the accelerator pump puts out in comparison to the float bowl volume is minuscule, look on the bottom of the foward bowl.. that little diaphragm with the lever hanging out is the accelerator pump.
 
Something isn't right if a new Carb gives the same starting problems as the old one. I mentioned a few posts back about an electric pump possibly eliminating the problem. Did you check, when cold, if the carb is putting fuel in when you pump the throttle. When cold take off Air Cleaner and look into carb and move throttle to see if its pumping gas. Could be weak fuel pump. As I said before Mopars love to start when cold.
 
oldbee said:
I would start with checking choke while cold, before starting. Barely crack throttle & watch for choke to close.
Click to expand...
But be sure the choke plate is not closed tight. If memory serves me correctly, it should have about 1/8 - 1/4' gap. If it is closed tight, you are literally choking off all intake air and that will make starting VERY difficult.
 
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