Carb's fuel bowl losing fuel, evaporating

I’d say a month.

Are you saying it always has done this, prior to the earlier fix you did?

Are you sure it’s an empty carb, and not a mis-adjusted or sticking choke?

A month? Seems more than I’d expect given the early 70’s design. My usual experience when driving the truck daily is the engine starts with about 1 second of cranking. Even every 3 days. But after a week, it has always taken noticeably more cranking. I haven’t driven the truck since before Christmas, and one drive a month will probably be close to its normal usage now.

@jtsanders has a friend with a similar era similar engine seldom used Mustang, maybe they’ll chime in with their experience.

If it’s always been like this, then I’d live with it, or spend $90 on a new carb from Amazon (I was surprised that Rockauto was out of stock) to see if it improved things, instead of putting on an electric pump.

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Tester

I haven’t decided on the electric pump idea. New carb vs live w/it? I’d just live with the extended cranking time before risking introducing new problems w/ a replacement. If there were an easy way to prime the fuel bowl using a small plastic bottle, that would work. I’d only need to do that at home base after a long lay-up. The reason I don’t is b/c removing the top is an annoying, awkward task. But if there were a way to introduce fuel into the carb bowl w/out removing the top, that would work.

You are thinking of someone else @George_San_Jose1. I don’t know anyone with a Mustang from the same time as your pickup.

I believe George is thinking about Gorehamj’s friend with the MSD dist that was wired up wrong…

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Oops, DMP above is correct, @GorehamJ is the poster… here’s the relevant link

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Do you folks get confused by repair manuals which don’t use the words you expect them to? Was referencing my trucks repair manual the other day. It refers to the carb’s “accelerating pump” in half a dozen places. I was expecting “accelerator pump”. Just curious, does anyone in the car repair business actually refer to that part as the “accelerating pump”?

Those in the car repair business don’t give a crap what it’s called.

We still know what it is.

Does a hand wheel position sensor. or a steering wheel position sensor confuse you?

Tester

Slang names would really confuse you if a very similar word such as accelerating and accelerator that are mostly spelled the same confuses you… lol
Dizzy for instance… lol

In service manuals:
evaporator core vs evaporator coil… propeller shaft vs drive shaft… processor vs ECM… the list goes on and on… As said, we just move on and don’t overthink it…

Thin carburetor die castings were commonly pressure impregnated with resin after manufacturing to eliminate leakage due to porosity from contaminants in the metal . Time, solvents, gas additives, cleaning procedures, can open up the porosity. The leaks can be so small that the fuel evaporates as fast as it leaks. Sometimes you can see a stain at the leak area.

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That seems like it would be hard to spot, leaks, but never a sign of a leak.

How old is the carb?

Well sounds like 1970 to 2024, at least
50 years old. A five second delay in starting seems like not much to worry about.

Don’t know if it’s original. If it is I’d certainly replace it.

I replaced the carb at about the 15 year mark w/a rebuilt unit.

So you replaced it in 1985? Still a 39 year old carb.

So you replaced a 15 yo carb, but don’t think a 35ish yo carb doesn’t need gone through or replaced??

Texasws beat me to it… lol

I rebuilt this carb completely a few years ago, and won an award here for my effort. I have removed and tested portions of it several times since for various reasons . It’s not 35 years since anything was done on it… lol … just last summer I removed the carb from the truck, removed both idle mixture needles, cleaned the idle passages , new top gasket & accel pump gasket, then did the “overnight over-a-container” fuel-bowl leak test. Replaced the power valve & its gasket several times as well.

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