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Can a guy have too much acceleration pump?
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56D500boy
Posted 2022-05-12 2:46 PM (#621424)
Subject: Can a guy have too much acceleration pump?



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Yesterday at my Healthy Heart walking group one of the guys told us how easily he got his beautiful 65 327 Corvette started after sitting unstarted for the last 6 months. One thing that he did was to pull the coil wire and crank the engine get oil pressure. Then he re-attached the coil wire and cranked the engine again. BLAM. Fired right up.

I don't think I reacted positively enough to his starting the story and the Karma gods thought they should smack me down. Just for fun.

I have started my 56 Dodge many times over the winter and even taken it out for a spin on dry dry/salt free days. So I was confident about starting it at any time. I also keep the battery up with a Battery Tender Jr. (Home Depot for about $35). Keeps the voltage at 12.85 V.

Apparently last Friday, after returning from Seattle, and starting the Dodge (for fun), I left the parking lights on and didn't discover that until Monday. Totally flattened the battery.

I got it charged on Tuesday and yesterday (Weds) I went to start the car to go to RONA (think Lowes) (any excuse to drive the car is fine with me).

Before I hit the key, I decided (stupidly) to touch the throttle pedal a tad in order to set the choke. I must have "tadded" it a bit too much because I apparently flooded the engine. WHAT?? That is crazy.

Cranked and Cranked. Try as I might, foot to the floor to open the throttle plates to get air in there and dry the engine out, and even took the air cleaner off and jammed the choke open with a screw driver, it would not fire (it was trying, but not hard enough to catch).

Eventually, I gave up and and gave it a very small squirt of ether to get it to fire. Then it started up first crank. Ran fine. WHAT!!?? Weird. After letting the engine warm up, it was off to RONA.

PS: I have never had to crank the engine as much as I did yesterday (I thought that I was either going to flatten the battery again or burn out the starter or both ). While I was cranking once, I glanced at the oil pressure gauge. WOW, I was cranking enough that it got to full normal pressure without the engine running. I have never seen that before with this car.

Anyway, hopefully the Karma gods are appeased now and I can carry on and have quick starts.

Now for the question: Do you think that I should adjust the accelerator pump stroke so there is less fuel going in? OR ???

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ronbo97
Posted 2022-05-12 4:44 PM (#621428 - in reply to #621424)
Subject: RE: Can a guy have too much acceleration pump?


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Did you verify that when you stepped on the gas pedal that it closed the choke ? My Plymouth's choke gets sticky from lack of use. Step on the pedal and choke remains open. So before starting, I verify that the choke is closed. Then a few cranks and all good.

Ron

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1960fury
Posted 2022-05-12 6:45 PM (#621435 - in reply to #621424)
Subject: Re: Can a guy have too much acceleration pump?



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By pushing the pedal to the floor once, with a cold engine? Certainly not. Keep in mind that most old car "experts" have the terrible habit of pouring gas down the carb throat to start it. What Ron said.
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56D500boy
Posted 2022-05-12 7:49 PM (#621442 - in reply to #621428)
Subject: RE: Can a guy have too much acceleration pump?



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Ron: I have previously verified that a slight tap on the gas pedal (say about 3/8" at the top of the pedal) is enough to set the choke (verified with the air cleaner off).

Sid: I did not "floor" the pedal on a cold, non-running engine, at least not initially. Once I figured out that it was flooded, I did push the pedal to the carpet (one push, not a pump and another pump - that just makes things worse) so that there would be lots of dry air pulled into the engine, in hopes of drying out the plugs.

Didn't work.

Lesson learned: I am not going to set the choke the next time I start it cold and I will see how that goes.

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local2Ed
Posted 2022-05-14 7:23 AM (#621465 - in reply to #621442)
Subject: Re: Can a guy have too much acceleration pump?


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I doubt a small tap of the accelerator flooded the engine.
More likely it did not deliver any fuel.
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wizard
Posted 2022-05-14 1:17 PM (#621471 - in reply to #621424)
Subject: Re: Can a guy have too much acceleration pump?



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Too rich automatic choke adjustment might prevent the vacuum piston from opening the choke valve slightly, hence the carb will act like flooded (actually is)
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PolyJ
Posted 2022-05-15 8:42 PM (#621517 - in reply to #621424)
Subject: RE: Can a guy have too much acceleration pump?



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56D500boy - 2022-05-12 12:46 PM . . . . Eventually, I gave up and and gave it a very small squirt of ether to get it to fire. Then it started up first crank. Ran fine. WHAT!!?? Weird. After letting the engine warm up, it was off to RONA. PS: I have never had to crank the engine as much as I did yesterday (I thought that I was either going to flatten the battery again or burn out the starter or both ). While I was cranking once, I glanced at the oil pressure gauge. WOW, I was cranking enough that it got to full normal pressure without the engine running. I have never seen that before with this car. Anyway, hopefully the Karma gods are appeased now and I can carry on and have quick starts. Now for the question: Do you think that I should adjust the accelerator pump stroke so there is less fuel going in? OR ??? :)

Hey Dave, From your description, I think you actually experienced fuel starvation rather than flooding, as local2Ed commented. The fact that you hit the pedal only once and the engine didn't fire with the throttle held open with a lot of cranking but fired right up after you gave it starter fluid goes against the case for flooding. Depending on the carburetor you are running and the accelerator pump shot volume, it takes more than five pumps on a cold poly, hemi, or A-block to flood it in my experience. In all likelihood, if you had pumped the pedal two or three times before going down your adventure of cranking, the engine would have fired right up. If it behaves similarly again, pump the pedal 2 - 3 times and try to fire it.

I'm not sure what kind of gas you get up north, but the 10% - 15% ethanol gas in the States can be problematic leaving it in the carburetor bowls over the winter without using a fuel stabilizer, and it can eat up older non-ethanol resistant seals including the accelerator pump. Your friend with the Corvette likely needs to crank the engine for a period in order to fill the float bowls since the gas would have evaporated over the winter if he never fired the engine. Ethanol-cut gas can leave residue that can plug circuits, so it's better to either remove the carb and drain it upside down each winter--not the best since it dries out the seals/gaskets--or leave it full of gas with fuel stabilizer.

 

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PolyJ
Posted 2022-05-15 8:49 PM (#621519 - in reply to #621442)
Subject: RE: Can a guy have too much acceleration pump?



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56D500boy - 2022-05-12 5:49 PM . Ron: I have previously verified that a slight tap on the gas pedal (say about 3/8" at the top of the pedal) is enough to set the choke (verified with the air cleaner off). Sid: I did not "floor" the pedal on a cold, non-running engine, at least not initially. Once I figured out that it was flooded, I did push the pedal to the carpet (one push, not a pump and another pump - that just makes things worse) so that there would be lots of dry air pulled into the engine, in hopes of drying out the plugs. Didn't work. Lesson learned: I am not going to set the choke the next time I start it cold and I will see how that goes. :)

What carburetor are you running, and what type of choke?

I'd confirm the accelerator pump is functioning properly and proper choke and fast-idle adjustment with the engine cold before the next time you fire the engine. Pull the air cleaner, look down in the airhorn with a flashlight, hold the choke plate open with a finger, and thumb the throttle wide open once. You should have a nice, consistent shot of fuel. If you don't you'll want to diagnose if the float bowl(s) is full. If so, you might have a bad accelerator pump seal or a plugged orifice. Once you confirm the accelerator pump is functioning properly, follow the specs for your carburetor to measure/set fast-idle and the gap between the choke plate and airhorn sidewall. Once you've confirmed the fast-idle and choke adjustments, pump the pedal wide open once and try to fire the engine. If it fires, which it should with one to three pumps, watch the choke plate as the engine warms to see how it pulls off including when you lightly blip the throttle by hand to actuate the different fast-idle cam steps as the engine warms.

While I'm confirming/setting the fast-idle and choke, I'd confirm the accelerator pump adjustment per the carburetor spec. I would not make any adjustments to the accelerator pump to troubleshoot the issue you described since you have not mentioned having acceleration issues such as lag or bog when driving the car when up to temp. I'd focus on one thing at a time, starting with the above.



Edited by PolyJ 2022-05-15 9:08 PM
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1960fury
Posted 2022-05-16 10:59 AM (#621526 - in reply to #621424)
Subject: Re: Can a guy have too much acceleration pump?



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For cold starting the function of the accelerator pump is completely irrelevant. You press the pedal to the floor not to pump fuel into the intake, thats why the manual says "gently", the sole purpose of that procedure (contrary to popular believe) is to close the choke valve.
If everything is in order the enrichment via the closed choke plate is all what it needs.
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dels56
Posted 2022-05-16 11:57 AM (#621527 - in reply to #621424)
Subject: Re: Can a guy have too much acceleration pump?


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Above comments are all good advice but....don’t get excited. If this is the first time this happened to you, don’t start tearing things apart. Give it another try under the same conditions. If the same thing happens then you know you have a bit of work to do.

Del S
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56D500boy
Posted 2022-05-16 12:26 PM (#621528 - in reply to #621519)
Subject: RE: Can a guy have too much acceleration pump?



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PolyJ - 2022-05-15 5:49 PM
What carburetor are you running, and what type of choke?


The carburetor is a stock 56 Dodge D500 Carter 2443S WCFB that was rebuilt/restored less than 3000 miles ago. The choke is an Echlin electric.

I had previously observed (with the air cleaner off) that only a slight movement of the throttle was needed to set the choke and get the carb on to the fast idle cam.

I never "floor" the throttle before starting. To me that is asking for trouble.

Normally just tapping the throttle (maybe a 1/4 of the travel) and then hitting the starter with my foot off the throttle is enough to start the car. The incident in my first post in this thread was an exception. Usually it starts right off (Pertronix ignition with Pertronix "Flame Thrower" coil and no ballast resistor - works great).

UPDATE: (from 10 minutes ago): Set the choke with a slight tap on the pedal and hit the key. Started right up. (Admittedly, I had started it yesterday while testing the neutral safety vacuum switch)

Thanks for all the hints, etc.



Edited by 56D500boy 2022-05-16 2:06 PM
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PolyJ
Posted 2022-05-17 10:12 PM (#621551 - in reply to #621526)
Subject: Re: Can a guy have too much acceleration pump?



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1960fury - 2022-05-16 8:59 AM For cold starting the function of the accelerator pump is completely irrelevant. You press the pedal to the floor not to pump fuel into the intake, thats why the manual says "gently", the sole purpose of that procedure (contrary to popular believe) is to close the choke valve. If everything is in order the enrichment via the closed choke plate is all what it needs.

You are interpreting "gently" press the pedal to mean "barely" press the pedal, which isn't what that instruction means. I was going to respond explaining exactly how the accelerator pump is a key component of the cold-start system particularly in weather below 40F degrees, but instead I'll simply ask you to prove that the accelerator pump is irrelevant as you claim. Please quote directly from a factory service manual or factory bulletin anywhere from 1956 - 1970 that explains the accelerator pump is irrelevant during cold start since I can quote from a number of manuals that explain the accelerator pump functions to provide the cold, dry cylinders with fuel for intial start before the carburetor has enough vacuum to draw in and atomize fuel.

 

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1960fury
Posted 2022-05-18 11:14 AM (#621556 - in reply to #621551)
Subject: Re: Can a guy have too much acceleration pump?



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PolyJ - 2022-05-17 10:12 PM

1960fury - 2022-05-16 8:59 AM For cold starting the function of the accelerator pump is completely irrelevant. You press the pedal to the floor not to pump fuel into the intake, thats why the manual says "gently", the sole purpose of that procedure (contrary to popular believe) is to close the choke valve. If everything is in order the enrichment via the closed choke plate is all what it needs.

You are interpreting "gently" press the pedal to mean "barely" press the pedal, which isn't what that instruction means. I was going to respond explaining exactly how the accelerator pump is a key component of the cold-start system particularly in weather below 40F degrees, but instead I'll simply ask you to prove that the accelerator pump is irrelevant as you claim. Please quote directly from a factory service manual or factory bulletin anywhere from 1956 - 1970 that explains the accelerator pump is irrelevant during cold start since I can quote from a number of manuals that explain the accelerator pump functions to provide the cold, dry cylinders with fuel for intial start before the carburetor has enough vacuum to draw in and atomize fuel.

 



I know because I drive my 1960 Plymouth almost daily for over 30 years, winters included. My garage separated from my house without any heat source. Up to 2 years ago, when I inherited a new car, I never owned a new car, newer than 1961.

You do NOT need the accelerator pump for cold starting (as the OP stated). That is why the manuals says gently or (sigh) "barely", that means there is hardly any pumping action.
I can unblock the choke when I park my car hot, so the that choke closes when the engine cools down. It will start the next morning without any pedal action/accelerator pump. That is the way it should be. Why would you want to dump fuel into the intake, if its starts w/o problems, just with the closed choke valve? I'm talking about normal temperatures, not -20 Fahrenheit.

I can't provide a quote from any shop/owners manual. I can't provide a quote from a manual that says cleaning the windshield has no effect on cold starts either. That "barely" says enough.


Edited by 1960fury 2022-05-18 11:28 AM
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1960fury
Posted 2022-05-18 11:23 AM (#621558 - in reply to #621551)
Subject: Re: Can a guy have too much acceleration pump?



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PolyJ - 2022-05-17 10:12 PM

to provide the cold, dry cylinders with fuel for intial start before the carburetor has enough vacuum to draw in and atomize fuel.

 



?!
So when you crank an engine (my 60+ year old starter with the battery in the trunk is very likely the slowest here) there is not enough vacuum to draw in "atomized" fuel from the carb? What a nonsense.
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1960fury
Posted 2022-05-18 11:35 AM (#621559 - in reply to #621551)
Subject: Re: Can a guy have too much acceleration pump?



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PolyJ - 2022-05-17 10:12 PM

the accelerator pump is a key component of the cold-start system particularly in weather below 40F degrees, but instead I'll simply ask you to prove that the accelerator pump is irrelevant as you claim.


One more thing, I just googled 40° Fahrenheit and it is 4.4° Celsius! You gotte be kiding. That must be the average temperature in my garage. Make your choke functional and stop wasting fuel, spark plugs, cylinder walls and piston rings

Edited by 1960fury 2022-05-18 11:38 AM
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PolyJ
Posted 2022-05-18 3:37 PM (#621568 - in reply to #621556)
Subject: Re: Can a guy have too much acceleration pump?



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1960fury - 2022-05-18 9:14 AM
PolyJ - 2022-05-17 10:12 PM

1960fury - 2022-05-16 8:59 AM For cold starting the function of the accelerator pump is completely irrelevant. You press the pedal to the floor not to pump fuel into the intake, thats why the manual says "gently", the sole purpose of that procedure (contrary to popular believe) is to close the choke valve. If everything is in order the enrichment via the closed choke plate is all what it needs.

You are interpreting "gently" press the pedal to mean "barely" press the pedal, which isn't what that instruction means. I was going to respond explaining exactly how the accelerator pump is a key component of the cold-start system particularly in weather below 40F degrees, but instead I'll simply ask you to prove that the accelerator pump is irrelevant as you claim. Please quote directly from a factory service manual or factory bulletin anywhere from 1956 - 1970 that explains the accelerator pump is irrelevant during cold start since I can quote from a number of manuals that explain the accelerator pump functions to provide the cold, dry cylinders with fuel for intial start before the carburetor has enough vacuum to draw in and atomize fuel.

 

I know because I drive my 1960 Plymouth almost daily for over 30 years, winters included. My garage separated from my house without any heat source. Up to 2 years ago, when I inherited a new car, I never owned a new car, newer than 1961. You do NOT need the accelerator pump for cold starting (as the OP stated). That is why the manuals says gently or (sigh) "barely", that means there is hardly any pumping action. I can unblock the choke when I park my car hot, so the that choke closes when the engine cools down. It will start the next morning without any pedal action/accelerator pump. That is the way it should be. Why would you want to dump fuel into the intake, if its starts w/o problems, just with the closed choke valve? I'm talking about normal temperatures, not -20 Fahrenheit. I can't provide a quote from any shop/owners manual. I can't provide a quote from a manual that says cleaning the windshield has no effect on cold starts either. That "barely" says enough.

 

In response to your bolded statements, exactly, you try to pass off your limited anecdotal opinion of driving one car as fact and tell other people they don't know what they're talking about because they call you out on the misinformation. You have no evidence to support your assumption that the accelerator pump has no function in the cold-start circuit because that evidence doesn't exist, whereas numerous carburetor manufacturers and auto manufacturers have literature discussing the accelerator pump's role during cold start and to inspect the pump when diagnosing cold-start issues. The fact is that mechanical carburetors equipped with a choke are designed to supply the intake with a priming shot of fuel for cold start, so one should verify the accelerator pump is properly adjusted and working when diagnosing cold-start issues such as Dave's. You have made it clear you disagree, but your opinion goes against factory advice and the understanding of how a carburetor works.

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wizard
Posted 2022-05-18 3:42 PM (#621569 - in reply to #621424)
Subject: Re: Can a guy have too much acceleration pump?



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Can a thread have too much comments?

When the automatic choke is working correctly, theres absolutely no rocket science.

- When the engine cools down, the butterfly valve closes and the bi-metal spring in the automatic choke chamber loads up.
- Driver shall just press down the accelerator pedal once, the accelerator pump gives a portion of fuel and the choke valve closes.
- The fast idle is set
- Engine starts and a vacuum function slightly opens the choke valve.
- Hot exhausts is forced under the carburetor for to heat up the base and also affects the bi-metal spring in the automatic choke chamber.
- As the engine temperature goes up, the butterfly valve opens up gradually.
- Fast idle drops to normal idle.

That is the function, cold or warm weather
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local2Ed
Posted 2022-05-18 4:53 PM (#621572 - in reply to #621569)
Subject: Re: Can a guy have too much acceleration pump?


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"Fast idle drops to normal"

Not without the tap of the accelerator pedal.
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56D500boy
Posted 2022-05-18 6:56 PM (#621579 - in reply to #621569)
Subject: Re: Can a guy have too much acceleration pump?



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wizard - 2022-05-18 12:42 PM
Can a thread have too much comments?


I do somewhat regret making my original post.

It's all good.

Car starts fine (again).

I do have to tap the throttle to take it off the fast idle cam (on the side of the carb). But that is no biggy.

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1960fury
Posted 2022-05-18 9:05 PM (#621584 - in reply to #621568)
Subject: Re: Can a guy have too much acceleration pump?



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PolyJ - 2022-05-18 3:37 PM

In response to your bolded statements, exactly, you try to pass off your limited anecdotal opinion of driving one car as fact and tell other people they don't know what they're talking about because they call you out on the misinformation. You have no evidence to support your assumption that the accelerator pump has no function in the cold-start circuit because that evidence doesn't exist,


One car? No I have/had severals, all carbureted Forwardlooks. I was driving a 61 Desoto coupe for years. But even if it was only one car, that would be proof enough for me. Not bragging, but I drove several 100 000s of miles with these cars.
You are claiming, that when you crank an engine the vacuum is not strong enough to suck in atomized fuel. That is absurd.

I don't care what anyone writes, I know that the accelerator pump is not needed for starting. Your only "proof" is literature, mine is the real life. I can provide literature that "proves" that the earth is flat.
I talk from personal experience and that "barely" in the owners manual gives a hint. Doesn't it? Why didn't they say "pump" or "strongly depress the pedal", if the accelerator pump is vital for starting?

OK, I will post a video with a dead cold engine once it gets colder, it is about 23 C° now.
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1960fury
Posted 2022-05-18 9:10 PM (#621586 - in reply to #621569)
Subject: Re: Can a guy have too much acceleration pump?



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wizard - 2022-05-18 3:42 PM

Can a thread have too much comments?

When the automatic choke is working correctly, theres absolutely no rocket science.

- When the engine cools down, the butterfly valve closes and the bi-metal spring in the automatic choke chamber loads up.
- Driver shall just press down the accelerator pedal once, the accelerator pump gives a portion of fuel and the choke valve closes.
- The fast idle is set
- Engine starts and a vacuum function slightly opens the choke valve.
- Hot exhausts is forced under the carburetor for to heat up the base and also affects the bi-metal spring in the automatic choke chamber.
- As the engine temperature goes up, the butterfly valve opens up gradually.
- Fast idle drops to normal idle.

That is the function, cold or warm weather


Nobody was denying that Wiz
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1960fury
Posted 2022-05-20 6:11 PM (#621626 - in reply to #621586)
Subject: Re: Can a guy have too much acceleration pump?



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It was a little cooler today. About 18°C. Stuffed 2 paper towels into to carb, below the accelerator pump nozzles and unblocked the choke valve, removed the towels carefully and let the butterfly close and noticed, to my surprise, that if you depress the pedal gently or barely, THAT IS WHAT THE OWNER MANUAL SAYS, that there is ZERO fuel comming out of the nozzles. This is what I did for 30 plus years. So I guess I didn't start my cars 1000 times and drove 100 000s of miles because they weren't starting?

Of course, the Fury started immediatly (despite slow cranking) like always and ran perfect. As I said, the accelerator pump is not needed for starting (at normal temperatures). Anyone can make that test. If it gets colder, I will do it again and post a video.


Quote PolyJ:

"the accelerator pump functions to provide the cold, dry cylinders with fuel for intial start before the carburetor has enough vacuum to draw in and atomize fuel"

"You have made it clear you disagree, but your opinion goes against factory advice and the understanding of how a carburetor works"


Again, that vacuum statement is absurd and I wonder if you actually know how a carburetor works.

Anyway, I think you proved who is the one with no understanding of carburetors (and engines).







Edited by 1960fury 2022-05-20 6:13 PM
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