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Posted By Discussion Topic: Empty Carb? -- page: 1 2     Dustbowl 10-23-2018 @ 5:07 PM reply profile send p.m. Member Posts: 74 Joined: Feb 2011 If my 36 Ford sits more than a week, it takes about 20-30 seconds of cranking before it starts. If less than a week, it starts immediately. I assume that in the week, the carb (standard 97) bowl dries out as gasoline evaporates. So I have to crank a long time for the fuel pump to fill the bow. Is my assumption of the problem cause correct and, if so, what can I do to eliminate or reduce the problem? Drbrown 10-23-2018 @ 7:51 PM reply profile send p.m. Senior Posts: 563 Joined: Nov 2013 If your carb doesn't leak internally or externally, then (some) gas is probably seeping back to the tank. I'm not knowledgeable but some stock mechanical pumps have valves in them to prevent back-flow to the tank. I believe one can also buy a back-flow presenter valve. In addition to its stock mechanical pump, and like some members at this forum, my '47 has an Airtex electric pump at the tank which I turn on for about 10 seconds before starting the engine. And its also available if the mechanical pump fails or the engine experiences vapor lock. ken ct. 10-23-2018 @ 9:54 PM reply profile send p.m. Senior Posts: 1513 Joined: Jan 2010 It shouldn't evaporate in a week. Try another Power Valve , 97's use a # 65. I have some if you need one. I also can test them for leakage with a tool I have. ken ct ford38v8 10-23-2018 @ 10:15 PM reply profile send p.m. Senior Posts: 2739 Joined: Oct 2009 Dustbowl, Ken may have hit on the cause of your losing fuel. Modern gasoline is not only more volatile than in bygone times, it is also destructive of diaphragms in fuel pumps and power valves. Drbrown, with all due respect, to my knowledge, all carburetors and all mechanical pumps have valves that prevent flow back to the tank. Therefore, adding an additional one way valve is additional redundancy. Alan mfirth 10-24-2018 @ 4:36 AM reply profile send p.m. Member Posts: 206 Joined: Nov 2017 Actually, todays fuel will evaporate quickly in a hot conditions. A marine mechanic i know put some in a jar & in an hour you could see the results of evaporation. I put an electric pump on my 52 Vic & use it to prime the carb or overcome vapor lock etc. Hope this helps, mike ken ct. 10-24-2018 @ 5:55 AM reply profile send p.m. Senior Posts: 1513 Joined: Jan 2010 Allen is right but Stromberg PV have NO rubber diaphragm in them. Simply a mechanical with an internal spring in it ,But they can still leak if they don't seat properly. Smell your dipstick for gas smell. ken ct TomO 10-24-2018 @ 9:07 AM reply profile send p.m. Senior Posts: 7244 Joined: Oct 2009 Drbrown, you usually post good information, but in the case of fuel draining back to the tank, it is almost impossible. The fuel inlet to the carburetor is above the fuel level, so there is an air gap in that the fuel cannot jump. The fuel pump sediment bowl fuel level may be high enough so that there is not an air gap, but once the fuel starts draining back to the tank, there will be an air gap. Mike, I have left a graduated cup, with 2 ounces of fuel in it, on my work bench for more than a week and very little evaporated. The summer grade fuel sold on the US is designed to have a low volatility to reduce air pollution and differs by state with the colder states allowing more volatility than the warmer states. A Ford fuel pump should prime in 18 seconds and fill the carburetor enough to start the engine in 30 seconds. If it does not, there is probably: an air leak in the supply line, the push rod is worn, the fuel pump is worn out or the line is plugged. Dustbowl's fuel pump is operating within specifications, so Ken's diagnosis of a leak in the carburetor is probably correct. Tom JT Ford 10-24-2018 @ 10:20 AM reply profile send p.m. New Member Posts: 112 Joined: Oct 2009 If you grind on a starter for 30 seconds, it seams like for ever! Drbrown 10-24-2018 @ 6:32 PM reply profile send p.m. Senior Posts: 563 Joined: Nov 2013 As said, I'm not as "knowledgeable" as you and many more experienced others here but I was remembering other posts re i.e leaking flex hoses at pump intake allowing air to enter the line when car sits and gas to drain back to tank, and/or when running allowing air to be sucked into pump etc etc.. And if it "sits for more than a week" ..... how much more ? mfirth 10-25-2018 @ 4:34 AM reply profile send p.m. Member Posts: 206 Joined: Nov 2017 Tom, thanks for the info. I'm in Ohio & every time i shut my 8ba with 180 stats,down the gas in the carb boils, expands & floods the engine. Have friends with various vehicles & they all experience the same thing. Boats using "marine fuel" do not. Isn't there a difference in formulations there too? Thanks 4 sharing your knowledge. m

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