Hi I am driving a 69 Dart with a 225 slant six and Holley 1920 installed.

After running when I turn off the engine, the fuel drains from the fuel line.

Is it immediate after shut down, or does it drain gradually? It is normal for an old car with mechanical pumps and unsealed tanks to bleed the pressure off while sitting.

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"if it aint broke, fix it till it is"
78 Plymouth Volare Super Six wagon
89 Volkswagen Golf GTI 16v
92 Chevrolet K1500 5.7
98 Ford Escort ZX2 zetech

It does not take very long, about 10 minutes or so. but I also get poor economy. I think it is either evaporating or leaking out of the lines somewhere. I recently installed a new fuel pump, and sending unit

Fuel drains from which line, & how do you know this? What symptoms are you experiencing? How bad is "poor" economy? What trans is in your car? What kind of driving are you doing (city-short trip, highway, etc)?

There are lots of things that affect fuel economy- but first- I don't know your experience with old carbureted cars. I've usually gotten 15-17MPG with my Darts (225"- automatic)- maybe 19-20 highway- & as low as 12 city in 20* winter weather. It's possible to get higher than that but it requires some careful: tuning, parts selection, & driving.

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63 Valiant Wagon
225 - 4 bbl

Rad ty. I do not know of a fuel leak, It just seems that she burns allot of gas. I drive mostly city and a little freeway, I'm getting about 15 so it seems to be in the ballpark. I have a torque flight 3 speed auto

Do you know if the ball has fallen out of the power valve? Have you looked and the econmizer body closely to see if it still place?

I had this problem once and the mileage dropped way down to 18 mpg. I thought what the heck? ..... I pulled the fuel bowl only to discover the power valve ball had fallen out. Glad I had a cut down red plastic Folger's coffee can shoved under the bowl to catch the gas as the ball, retainer and spring rolled out.
After pulling the economizer body I carefully reinstalled them and restaked the retainer on both sides (mine has two power valve balls, dual plunger) so the ball and spring couldn't fall out again. Back to 25 mpg!

All I can say is that those unexposed holes for the power valve drink down way more than a #64 jet that I used last time racing at the track.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

It was a $#!+ locking gas-cap Kragen sold me. I took the gasket off, put it on the stock one, and now my filter stays full

If the locking gas cap wasn't venting, and vacuum was building up sucking the gas back from the line, it means your vent line on your filler tube is probably clogged...

bg

Try this test...
Remove the air cleaner assembly and run the engine untill hot.
(Choke is completly open)

Shut the engine off and then look down the barrel of the carb.
Watch for a minute or two, to see if any gas is dripping down into the intake manifold.
If you see any drips, after engine shut-off, replace the needle valve in the carb, then re-test.
A leaking needle / seat can cause hot restart problems and hurt your gas mileage
DD

I solved the issue, the locking cap was not sealing, so I installed its gasket on the factory cap and the fuel line now stays full