Difficult to start cold engine, or one sitting overnight

[carbking]

There have been a number of threads on this subject. The following paragraph is from the troubleshooting page on our website:

 

HARD STARTING, COLD

Difficult starting a vehicle that has been allowed to sit for a number of days (that will then start well the rest of the day) is often caused by modern fuel. Modern fuel begins to vaporize (evaporate) at a much lower temperature than fuel before the 1970’s. Once the engine is shut off, the fuel in the carburetor bowl begins to evaporate through the bowl vent. If there is no fuel in the carburetor, the engine will not start. Pumping the footfeed during this time simply prolongs the agony, as the accelerator pump will pump the fuel into the engine, but in amounts insufficient for starting. If you have this problem, try priming the carburetor by using an eyedropper and filling the carburetor bowl through the bowl vent prior to cranking the engine. If you do not wish to prime the engine, crank the engine for 15 to 20 seconds WITHOUT PUMPING. Then stop cranking, pump the footfeed 3 or 4 times, release it, and then reattempt to start the engine. Priming eliminates excessive wear on the starter.

End of troubleshooting tip.

There are many other possible causes (most of them ignition related), but if fuel is the issue, the above is probably the cause. Trying the priming tip will let you know if this is the issue, or something else.

I have read some interesting comments concerning other possible issues, particularly the fuel leaking from the carburetor back to the tank. This is possible in very few downdraft carburetors (unless the operator parks the vehicle on its top!!!  ), as most downdraft carburetors have the fuel inlet above the discharge nozzle(s).

A similiar leak-down (into the engine, not the tank) is possible with the Holley type AA-1 (a.k.a. Holley 94) carbs, as the power valve drains directly into the manifold. A blown power valve will allow the carburetor bowl to drain directly into the engine.

Also possible for the Holley type 4000 (a.k.a. "brain-box", "teapot", "haystack") to SYPHON the bowl dry through the secondary jets, if the secondary air-bleeds are clogged. This happens because the owner or mechanic is too lazy to read the service bulletins (or his/her shop manual) and has led to the term "towering inferno". This is not the fault of the carburetor.

But I digress, if you do experience difficulty in starting an engine that has not run for a day or too, try the priming tip. I have had to install electric fuel pumps on several of my cars. IF YOU DO INSTALL AN ELECTRIC FUEL PUMP: Federal law mandates permanent wiring on either an inertia switch or an oil pressure switch (gee, a federal law that actually makes sense  ). You can then also wire a spring-loaded push-button type switch to fill the carburetor before starting.

 

Jon.

 

[Reg Evans]

I usually keep a mustard squirt bottle around filled with gas.  I just loosen the wing nut on top of the air cleaner and squirt about a tablespoon full of gas down the hatch.

I've installed an elec. fuel pump on one of my 7 old MoPars and that one always starts right up.  I just need to know where I can buy pre 70's gasoline ?

 

[JACK M]

Reg,

Try your local racers, they sometimes use Leaded high octane gas intended for off road use.

I deal in 120 and 110 gasoline that is leaded and very stable. (not the actual octane posted at the pump)

By the gallon or by the drum. To bad you are not closer.

 

By the way, its not cheap.

[47windsor]

i HAVE INSTALLED A 6 V Electric Fuel Pump in line as close to the gas tank as possible. I clicked the pump on this AM after the car had been sitting for 2 days & it hasn't made any difference. in starting.  I left the electric fuel pump on for about 1 Min-- could this have flooded the carb? What would be the suggestion 3 or 4 seconds?

 

Bruce Watson

[Spinneyhill]

The carb has a float and needle valve in it to prevent over filling as long as you have the pump delivery pressure right. To high will flood it.

 

Tell us again why you put the pump in? What was the symptom you overcame? Are all the ignition components in good condition, timing set correctly, good points set correctly, terminal connections in the ignition circuits clean and shiny?

 

 

[JACK M]

The auto parts store will sell a small inline regulator. Set it at 2-3 lbs.

I suppose you could put it anywhere inline but they usually suggest near the carb. For sure after the pump.

[47windsor]

Thank you for your interest from New Zealand. I bought this car a year ago & it runs very well , the only problem is starting the car.  If the car sits even overnight  it will crank over 17 times before it will start,

I will normally prime it with a small amount of gas & it starts with 2 cranks of the engine. As we do some touring I thought instead of doing the priming an electric fuel pump would assist in starting the car without all the wear & tear on the starter .  But I found that it hasn't made any difference.  As far as the electrical ,Plugs are new, points are new, rotor& condenser are new,  timing is right on the mark. Making all these changes didn't . 

change in the long cranking to try & start the car.  I understand that the fuel can evaporate from the bowl in the carb & thus the priming to assist in the starting. This problem of hard starting when cold appears to be common, especially with the fuel used to-day.

 

Bruce Watson

[Spinneyhill]

Might you have an intake vacuum leak?

[47windsor]

Thank you all for your input, The problem was in the auto choke which I have resolved.,

 

Bruce 

[JACK M]

Usually something simple.