Re: IML: Fuel Siphoning

[RandalPark@xxxxxxx]

I can say that when the cars were new, or at least much younger than they are now, they were not hard to start unless they were parked for a VERY long time. Several of mine will still start very quickly, even if they have been parked for a month or two.

Two of my cars with Carters that are giving this trouble have clogged primer jets. My '63 was this way. I was able to remedy it (on the advice of a friend) by using a piece of very fine wire to clear through the opening in both jets. They are visible in the top front portion of the carb. Once open, I can see them spray when I pull on the throttle. They become clogged due to rotten gas sitting in the carb.

The '68 has an original Holley. I have not studied it to determine if it could have a similar problem as above. The car has a brand new fuel pump. Since you say that the fuel pump's built in check valve should prevent it, I will guess that the fuel in the line is not running back from there into the tank. I could install a filter with a check valve, but have not yet done so.

I'll bite, yes, I would like to know, where does the fuel in the '68's fuel line go? I have a glass in-line filter that I can see is empty after the car sits overnight. Some of my other cars retain fuel (visible in the filter) for periods much longer than a few days. I can imagine that if there are some bad seals in the carb (or someplace), the conditon could allow enough air exposure to hasten it to evaporate. Is it possible that the fuel in the line is hot enough to have expanded to the point that it would nearly disappear once cooled off?

This inquiring mind wants to know.

Paul W.

In an email dated 31/8/2005 1:02:05 am GMT Daylight time, "mike and linda sutton" <mikanlin62@xxxxxxxxxxx> writes:

>Today there was a post about fuel siphoning back thru the needle and seats 
>after the car was shut down. ?It did not mention whether is was a Holley or 
>Carter carb, but since this is the Imperial list, we can presume it is an 
>Imperial and probably an AFB or a Holley, ?at the long shot a thermoquad. 
>Before going any further, it is not my intent to start a flame war or a 
>peeing match about this, and that I do in fact respect the person who made 
>the post and that Im not disputing their knowledge or experience.
>
>Having said all that, this has been cussed and discussed , peted and 
>repeated many times on this list. ?The general complaint is the excessive 
>cranking required in some Imperials before they will start, and is generally 
>attributed to lack of fuel in the float bowls. ?The causes , in no 
>particular order , have been attributed to heat soak after shut down causing 
>fuel to boil off in the bowl, ?leaks from porosity or cracks , ?and the 
>difference in todays fuels versus the fuels of the past in how easily the 
>evaporate.
>
>Now, my question...HOW can fuel siphon back thru a needle and seat after 
>shut down. ?The needle and seat are higher than the level of fuel in the 
>bowl and once the fuel pump was to stop pumping, the column of fuel 
>contained in the line to the needle and into the bowl would cease to be 
>filled completely full , which would not let a siphon action occur. ?Also, 
>the check valves in the fuel pump should stop it from flowing backwards any 
>further than the pump. ?I cant believe that there are that many Imperials 
>running around with fuel pumps with this condition. ?I have analyzed this 6 
>ways to Sunday and I just cant get there from here. ?This should be in the 
>archives, so feel free to dispute me all you please, I just want to see an 
>explanation for this phenomenon.
>
>I know the problem is real enough, it happens on my 62 now and then. ?I have 
>installed opaque fuel filters in the line to the carb and watched the fuel 
>in the line before. ?There is always a bit of an air pocket in the filter 
>when I shut the car off, but the level never drops down completely. ?That in 
>itself dispels the siphon theory as far as I can see
>
>Ok, inquiring minds want to know??
>
>Mikey
>62 Crown Coupe 
>
>
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