Dry Carb after sitting for a week.

MJFUR

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69 Chrysler 300, 505ci, 4640S. Everything is new or recently overhauled, new fuel tank, fuel lines, fuel pump, 4640s overhauled by Woodruff, newly overhauled engine, distributor, coil, etc.. The choke is not hooked up and is open all of the time. It's Texas, it's hot, it's not the issue.

When you drive the car daily or every couple of days it starts right up. Two pumps of gas, crack the throttle blade, crank it and it fires right up, idles and drives as it should.

If the car sits a week or two, it would need to be cranked for 15-20 seconds before starting. I had spark, but no gas.
Went out today after sitting 10 days, two pumps of gas as I looked down the carb, no gas spray from accelerator pump. Pulled fuel line from carb, cranked the starter, took about 8-10 seconds before I got fuel to pump out of the line.

It appears that the fuel is draining down back thru the fuel line and leveling with the fuel tank. I wouldn't think it could siphon fuel out of the carb though. There is never a fuel smell in the garage.

Once fuel gets pumped back up to the carb, car runs and starts as it should until it sits for a week or so.

What gives?

Thx

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Loadrunner

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1st of all, make dang sure it's not going into the cranckcase. I've seen it happen on a 6 pack set up and the engine exploded on start up, blew out some tin.

Smell your oil, and feel it.

And the level should not be going up.

Otherwise, this is fairly normal, usually points to a weak fuel pump letting fuel go back to the tank, but the fuel should stay in the carb, prob just the heat.

2 things;

Install electric primer pump to get gas up to the engine after long periods of sitting, works like a charm, this is factory installed on our FMC 800 gallon Ford pumper fire truck.

Prime your carb before trying to fire engine.

Loosen wingnut, pour small amount of fuel down small well under wingnut, leave air filter lid on, start engine. Repeat gas application second time if needed.

Tighten wingnut, drive.

Are you sure your accelerator pump is shooting correctly when the float level is correct?
 

Boydsdodge

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This is going to happen with the available fuels, non ethanol will slow the loss from carb. My wagon has an electric carter pump, due to a failed fuel pump push rod. The up side is the wagon starts right away after I let the pump run a couple of seconds.
The other cars will take longer each day the car sits, but they will start unless they have been sitting a year.
If you go with an electric pump, be cautious of your mechanical pump failing and allowing the electric pump to fill your crank case.
I would go either electric or mechanical, but not both. I will say Never say never.
 

Big_John

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I bought a cheap, flow through electric pump that I mounted back by the gas tank. To control it, I have a momentary contact switch under the dash and a relay.

When the car has sat for a while, let's say a week, I hit the switch until I hear the pump sound change (meaning the carb is full), release and start the car.

So, the mechanical pump works all the time and the electric only works when I want it too.
 

1970FuryConv

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My 1972 Fury did the same thing. All the fuel evaporated out of the float bowls after a week. Increased volatility of today's fuels is a problem. Electric primer pump is a good idea.
 

Toolmanmike

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Puppy pee gas is the worst. Non ethanol is the best. A drink of Sea Foam or Marvel Mystery oil in the tank may help. Here is a couple pumps like Big John mentioned that you can install to fill the carb up with a push button switch. . Check the information to make sure fuel will pass through when the pump isn't running.

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MJFUR

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While I agree that an electric pump can fix the condition, I don't think it addresses the problem.

I had a 1970 Corvette, 350ci, quadrajet, that could sit for a month or two and didn't have the starting problems with the same gas in the same garage.

It's hard to believe fuel is/can be evaporating out of the carb and the fuel line all the way down to the pump.

Thx again.
 

Toolmanmike

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While I agree that an electric pump can fix the condition, I don't think it addresses the problem.

I had a 1970 Corvette, 350ci, quadrajet, that could sit for a month or two and didn't have the starting problems with the same gas in the same garage.

It's hard to believe fuel is/can be evaporating out of the carb and the fuel line all the way down to the pump.

Thx again.
The problem is the fuel and the Edelbrock/Carter style carb. Q jets and Holley's are still effected but not as susceptible. A carb spacer helps a bit as does a return fuel system but neither are a cure. You can go out for a spirited drive and pull into your garage and hear the fuel percolating in the carb. My 2 barrel in my 70 Swinger does that.

A stuck heat riser will aggravate it as well.

You can chase the cause of the issue but the cause of the hard starting after setting a week there is no gas in the carb because it has evaporated. The electric charge pump cures that ill.
 

CBODY67

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ONE advantage that the QJet might have in this case is its very small float bowl. As soon as the gas gets in there, the bowl if pretty much full. Whereas the Carter has a lot more area in the float bowls, by comparison.

IF you want to manually fill the Carter float bowls, use the bowl vent tubes rather than pour fuel down the venturi! Much cleaner to do it that way.

On '73 Imperial Calif-spec cars, IIRC, they had a booster fuel pump mounted out back by the fuel tank. Just a small unit, from the looks of it in the manuals.

I have some friends in another car club who have mounted the small, booster, low-pressure electric pumps near the fuel tank on their mid-50s cars. In normal use, the electric pumps are not turned on, except in times of possible vapor lock (which the brand of car was somewhat known for, even back when they were new). In the situation at hand, they could also be used for initial start-up after a good while of vehicle non-use, too.

Just some thoughts,
CBODY67
 

Big_John

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While I agree that an electric pump can fix the condition, I don't think it addresses the problem.

I had a 1970 Corvette, 350ci, quadrajet, that could sit for a month or two and didn't have the starting problems with the same gas in the same garage.

It's hard to believe fuel is/can be evaporating out of the carb and the fuel line all the way down to the pump.

Thx again.
I don't have a good reason why this happens on some cars more than others. I wish I did.

Example, my AFB equipped '65 Barracuda will fire up pretty fast, even after it's sat for the winter. My Thermoquad on my '70 300 won't start up with out a lot of cranking if it sits a week. The electric fuel pump solved the issue for me.

The carb inlet is above the bottom of the fuel bowl in the Thermoquad, so syphoning back to the tank and emptying the fuel bowl isn't happening. Maybe... there's a drain back or syphon that happens in the fuel line. That might make more sense... The diaphragm pump has to draw another foot and a half for my Chrysler over the Barracuda and really, the pump is better at pushing fuel to the carb over drawing from the tank. That's another possibility too... Think how short the line must be in the Corvette. BTW, electric pumps are generally worse at pulling gas through the line, but I digress.

I use primarily ethanol free fuel in both cars, but the newer formulations do evaporate much faster, so you have that.

If I was going to test it, I would put something over the carb to block evaporation and see what happens. Although, most of the evaporation probably happens when the engine is hot after being parked with the remainder of the gas in the carb evaporating. If the syphon theory is possible, a simple one way valve in the line would stop it.
 

livininharrow

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my 64 dart slant and my 65 340 barracuda do the same thing with good fuel. pump the shit out of the pedal while cranking and magic happens.
 

'66 Fury I

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I am having this problem also. It began abruptly when I was forced to use ethanol laced fuel. The idea of fuel siphoning/backflowing through a working mechanical fuel pump is next to impossible. A diaphragm pump contains two spring loaded check valves. Either of these will preclude any backflow and if either of them is leaking, the pump cannot pump.
I have an electric pump to install as soon as time permits.
Lindsay
 

413

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Yea, my cars will do it, or not, depending on what fuel is in the tank.

Pump the shit out of the pedal is not good for the accerator pump on a carter carb With no fuel inside. Just fill the float bowl, it so easy to do. Then it starts right up.
 

Loadrunner

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Some engines are better than others at starting, why?

Compression, valve timing.

Some of the better starters I've had were rebuilt. A wideblock in particular, always starts on 1st crank in the spring.

And the rebuilt 318 in my Adventurer, actually started nearly on 1st crank after not having a radiator for well over a year. The engine also has the most abrupt shutdown of any that I have, it's still tight.

Just to save on starters/flywheel gear teeth, I always prime a Mopar engine that's been sitting, but the downside is instant firing.

If you want to build up some oil pressure before starting, then this no start situation can be handy.
 

Ross Wooldridge

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My wagon does this too... not really worried about it. I just set the choke and crank it...

I would not crank for more than 10 seconds, with a 5 second or longer break to allow the starter to cool off.

Don't pump repeatedly either, as this can shorten the life of the accellerator pump diaphragm if there's no fuel in the carb.

Pump once and crank. 10 second spurts with breaks, until it starts to catch - then pump a bit.
 

1970FuryConv

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The problem is the fuel and the Edelbrock/Carter style carb. Q jets and Holley's are still effected but not as susceptible. A carb spacer helps a bit as does a return fuel system but neither are a cure. You can go out for a spirited drive and pull into your garage and hear the fuel percolating in the carb. My 2 barrel in my 70 Swinger does that.

A stuck heat riser will aggravate it as well.

You can chase the cause of the issue but the cause of the hard starting after setting a week there is no gas in the carb because it has evaporated. The electric charge pump cures that ill.
Agree. The carb on my 72 Fury was Edelbrock 1406. Aluminum intake. Heat x-over blocked. Every week I had to turn over the engine a few times to get fuel back into the carb. I never heard fuel percolating.
 

CBODY67

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Even back in the later 1960s as our '66 NEwport 383 2bbl was becoming a great "used car", it had the "normal" extended crank time to start after a hot shutdown. I went through some of the same trouble trees y'all are looking at for guidance and after talking to some people who had driven Chrysler products and worked on them, it was just what could be termed "nature of the beast" in TX. So we tried to refine the starting techniques from the Owners Manual recommendations. At worst, no "instant start" and at best, just a few seconds longer crank time. "Longer than 10 second" starter engagements caused no starter durability issues, either, from our experiences . . . but if it didn't happen in what felt like a decent amount of crank time, cranking stopped. BTAIM

During these learning times, as this was our first "modern" Chrysler product (after '51 and '56 Plymouth 6-cyls), I watched what other brands of cars did under similar situations. Most started a second or so sooner than our Chrysler did, by observation. No black smoke from the exhaust either, from ours or theirs. Later, I investigated the carb design differences between the Rochesters and Stromberg (our Chrysler had the Stromberg WWC3 on it). "Gotta be something that gets the fuel into the venturi cluster quicker on those Rochesters", it seemed. But no significant issues seemed to be there, hot or cold. Everybody was using points back then (that's all we had!), so that made the ignition system "common" among all cars. It usually seemed that engines with a bit more basic ignition advance started a bit quicker than those without, but our Chrysler was spec'd at 12.5 degrees BTDC rather than less.

When we got the '72 Newport Royal 400 2bbl (with the then-optional Electronic Ignition), it did seem to start better. Other than the ignition system, it had the Holley 2210 carb, which I considered to be an advancement over the Stromberg. But it also had the 8.2 CR and a bit hotter cam than the old 383 2bbl did, if that might matter. Still, it seemed that after a hot "soak", the restart seemed to take longer than similar Ford or GM products. Which was BACK when lead (although in decreasing amounts) was still in the fuel, too.

In the 1990s, in the back of the Chevron website, there was an extensive section devoted to "ReFormulated Gas" (RFG), which had more ethanol in it to combat the low oxygen levels in the Colorado atmosphere during the winter months, back then. RFG was the first "oxygenated" fuel, with ethanol being that oxygenate. MTBE was another oxygenate that seemed to work just as well, but was known carcinogenic. When that "battle of the best" went to court, the court decided to basically split the mix of ethanol and MTBE at almost 50-50, so the mix of oxygenates became federal law. UNTIL . . . minute traces of MTBE were discovered in many municipal ater supplies several years later . . . from rain and similar. So the legislation was amended to make ethanol the main oxygenate. Over the later years, "bio-butanol" was another oxygenate which caused NO automotive fuel system problems, ever at 15% concentrations and also had similar CO2 reductions as E10 fuels, but it never seemed to get the support it needed, for some reason, although it could be built in ethanol plants which could be converted to produce it. BTAIM.

Some operatives, in particular states determined that by lowering the Reid Vapor Pressure of the gasoline that evaporative emissions could be decreased, too. SO . . . no universal ethanol'd fuels. In the back of the Mobil website, there used to be a map of the United States and the various types of fuels required in the respective areas. With the major specs denoted by various colors. LOTS of variations! Plus LOTS of areas where E10 is not needed, but due to distribution networks, is probably the dominant fuel available.

In the several websites which map the availability of ethano-free gas, it should be noted that most are near marinas. ALSO that most of the non-ethanol'd fuels are of lower octanes than many of our older cars can tolerate (think 87 pump octane or lower). 100 Research Octane unleaded and ethanol-free gas might still be available in drums and/or at some dragstrips (sold by vendors and not the drag strip itself). Storing larger "amounts" of flammable liquids in garages and such can come under local ordinances, I highly suspect.

As most cars are now fuel injected, the issue of hot restarts has seemed to disappear from normal sight. Turn the key, the computer is commanded to do all of the things in order for the engine to start, in milliseconds, and the engine starts and we drive away. Which, by comparison, makes any engine which takes three revolutions to start, "needing work". And that is the world we are now living in, to me. NOT to forget that we are now MANY generations deep into the situation where many techs have only read of "carburetors" rather than having grown up with them. Same with ignition points, too.

So, to conclude . . . the hot restart issues are decades old and just part of the deal with a Vintage Chrysler produict. You can tweak your individual combination of carb, ignition, and fuel supply system and/or use an electric fuel pump primarily or as a booster to help with the "extended non-use starting issues", too. Which is a different issue, but kind of related to, the hot restart issue. LEARN what your individual vehicle likes best, rather than wanting it to do as you might desire! As with so many other things in life, when you both work together to make everything operate as best they can, things get better and more enjoyment can happen.

Y'all enjoy!
CBODY67
 

garyh

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I have the same problem with my '66 Imp. Did a new mech.fuel pump and pushrod and it made no difference.I use 93 ,Non Ethanol gas. I had a thought that the Oil Cos. do a "Summer Blend" and a "Winter blend".I am not sure if that pertains to No Eth.gas.
 
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