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Discussion Topic:
Fuel Pump Problem?
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doning |
09-19-2011 @ 3:11 AM
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New Member
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For awhile now, as you probably remember in my past posts, I have a hard start with my 1937 85 HP in the mornings because the gas disappears in my fuel bowl. For the heck of it my father and I attached a brass nipple to the oulet of the fuel pump ( original design ) and installed a clear fuel line and tighted it to one of the radiator support rods and filled the line with gas and marked it. This morning before I went to work the gas in the line is gone! Is this going back into the tank? If so, how could it get by the two valves inside? The fuel pump was purchased new about 7 years ago and this is the first run this year with it. Thanks.
This message was edited by doning on 9-19-11 @ 3:12 AM
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trjford8 |
09-19-2011 @ 7:00 AM
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Senior
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A fuel pump purchased 7 years ago may not be up to handling the job with the change in fuels that we have today. Methanol is tough on rubber parts. The fuel pump diaphram and the flex hose to the pump can both be affected by the new fuel.
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JM |
09-19-2011 @ 8:15 AM
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It sounds like the one way valve to stop gas from flowing back from the FP to the gas tank is not working. Maybe you could get Ken CT to sell you a good FP rebuild kit. Or purchase a good rebuild kit from another well known source. I bought some from MAC's that were good and they get their kits from Joblot. JM
This message was edited by JM on 9-19-11 @ 9:05 AM
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doning |
09-19-2011 @ 9:14 AM
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JM: The only kit that I saw from Mac's was the rebuild kit for the glass bowl type. I have the earlier design.
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supereal |
09-19-2011 @ 9:21 AM
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I don't suscribe to the "drain back" theory, but it is certainly true that the pump valves and diaphragm quickly deteriorate in the presence of ethanol. This weakens the pump, if it doesn't stop it altogether, making refilling the carb require lots of cranking. The "vapor pressure" of modern fuel makes it suscepible to rapid evaporation, particularly when it is heated. Low surface tension allows gas to bypass the pump valves if they don't seat completely. If you are unsure whether your pump is "fuel proof", it is a good idea to replace it "just in case".
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doning |
09-19-2011 @ 9:28 AM
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New Member
Posts: 158
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Ok. Thanks Guy's. I think I might just as well buy a whole new pump. MAN! It's an on going thing with this car!
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kubes40 |
09-19-2011 @ 11:04 AM
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Posts: 3394
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Like Super, I too do not subscribe to the 'siphon back to the tank' theory. Most often, the fuel is evaporating and / or leaking down in to the intake.
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ford38v8 |
09-19-2011 @ 2:04 PM
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Likewise on the drainback theory, but I just got this crazy idea: I wonder if the new flexhose with the one way valve would make any difference in anything if used in conjunction with the removal of the fuel pump inlet valve? I suppose technically, all it would mean is moving the valve backstream a bit from the pump body to the flexhose. Just brainstormin'.
Alan
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supereal |
09-19-2011 @ 2:45 PM
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I think it is kind of a "belt and suspenders" idea, but I'd just swap the pump and be done with it. For what the flex hose with check valve costs, you can go to NAPA and get the whole pump.
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ford38v8 |
09-19-2011 @ 6:50 PM
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Senior
Posts: 2758
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Bob, my idea was intended as a way to use the "correct" pump, as some early pumps no longer have replacement valve availability. Belt and suspenders reminds me of the ancient dude in the grocery store today that got in the way of my wife on her electric shopping hotrod. The poor guy didn't know which way to go, realizing that with his high beltline, toupe and ballcap, he represented bonus points for a direct hit. My wife had compassion, we all had a good laugh, and he lived to shop another aisle.
Alan
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