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Old 08-25-2017, 10:33 AM   #1
markdtn
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Default 8BA Fuel pump quandry

On my 8BA in a tractor, I bought a new '52-53 Airtex fuel pump. It put more fuel in the crankcase than it did the carb. So I gravity fed it from a lawn mower tank during the construction phase. I am finally ready to put the sheet metal on so I bought a permanent tank. Only problem is that the tank is top draw as I bought a stock tank. A custom tank with bottom draw was over twice the price. (and I would have to pull the intake and add a plug to really get rid of the fuel pump pushrod. And I like the look of a pump). So I bought another new pump. This time a '49-51 style pump. Also an Airtex. So my questions: Why would a new pump leak internally? From all I read either early or late pump is OK for an 8BA? Is there something I should check as far as pushrod height or anything? I don't need much flow, motor is bone stock with a single 94 carb. Shouldn't brand new pump diaphragms handle ethanol fuels? Any other thoughts or suggestions? I do not want to fill the crankcase with fuel again.
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Old 08-25-2017, 11:02 AM   #2
JSeery
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Default Re: 8BA Fuel pump quandry

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Originally Posted by markdtn View Post
Shouldn't brand new pump diaphragms handle ethanol fuels? Any other thoughts or suggestions? I do not want to fill the crankcase with fuel again.
Maybe and maybe not! I would check with someone like Charlie NY here on the Barn. He can provide you a source for a ethanol prof diaphragm.
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Old 08-25-2017, 11:05 AM   #3
rotorwrench
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Default Re: 8BA Fuel pump quandry

You need to find a way to verify that the pump is the leak but it may not be the culprit. Your carburetor could be the source of the leak as well. Raw fuel from a leaky carb will seep right through static intake valve guides if the fuel leak is substantial.
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Old 08-25-2017, 11:51 AM   #4
markdtn
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Default Re: 8BA Fuel pump quandry

Hmmm. With gravity feed, a quart or less of fuel lasted like 15 min at idle. With the pump it was 1/2 gallon in about a 1/2 mile coming back from the muffler shop plus it used another 1/2 gallon or so while there (I was running out of a gallon jug and he made me bring more fuel). Not sure you could leak that much and it still run OK. Looking down at the carb when running it didn't look excessive either with or without the pump. How could I best tell if it was carb or pump?
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Old 08-25-2017, 01:33 PM   #5
JSeery
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Default Re: 8BA Fuel pump quandry

It's most likely the pump.
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Old 08-25-2017, 03:02 PM   #6
Bruce Lancaster
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Default Re: 8BA Fuel pump quandry

Why not just hook up the gravity tank again and see if you have the leak still? That will speedily tell you if pump is the problem.
Also check pressure...I've heard of new flathead pumps coming through with 7 pound diaphragm springs from much later model applications. I have no idea if that could apply to Airtex, but I'd sure check.
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Old 08-25-2017, 03:59 PM   #7
markdtn
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Default Re: 8BA Fuel pump quandry

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Originally Posted by Bruce Lancaster View Post
Why not just hook up the gravity tank again and see if you have the leak still? That will speedily tell you if pump is the problem.
Also check pressure...I've heard of new flathead pumps coming through with 7 pound diaphragm springs from much later model applications. I have no idea if that could apply to Airtex, but I'd sure check.
At this moment the gravity tank is still there. I will install the new pump next week. I was positive it was the pump until above. I am still pretty sure it's the pump. I will run it a little before I swap pumps. Nobody is saying there is any dimension I should check on the pushrod. The pushrod came with the engine, but the casting was broken so I bought one from a HAMB member. I just don't want to have any more gas in the oil. Wanted to be sure that I was covering all the bases so to speak. Thanks!
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Old 08-25-2017, 07:10 PM   #8
Charlie ny
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Default Re: 8BA Fuel pump quandry

mark,
Crank the motor over until the push rod is full up....take the pump with the stand attached and place it on the motor and carefully press down until the free play is taken up. At this point ideally there should be a .200 gap between the bottom of the stand and the pad that it bolts to on the intake. This .200 is the ideal pumping travel
of the pump. Let us know what you get then the saga might have to continue.
Charlie ny
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Old 08-28-2017, 09:52 AM   #9
markdtn
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Default Re: 8BA Fuel pump quandry

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Originally Posted by Charlie ny View Post
mark,
Crank the motor over until the push rod is full up....take the pump with the stand attached and place it on the motor and carefully press down until the free play is taken up. At this point ideally there should be a .200 gap between the bottom of the stand and the pad that it bolts to on the intake. This .200 is the ideal pumping travel
of the pump. Let us know what you get then the saga might have to continue.
Charlie ny
Thank you! I will try that in the next day or so.
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Old 08-28-2017, 11:32 PM   #10
fordor41
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Default Re: 8BA Fuel pump quandry

fuel pressure too high with the airtex pump. need a regulator.
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Old 08-29-2017, 02:42 PM   #11
Bruce Lancaster
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Default Re: 8BA Fuel pump quandry

Or if you have a dirty old pump in your junk pile, try an old spring. Squeezing it by hand will easily show a huge difference between a spring from the day when pumps were made or rebuilt by parts companies making them for use and those making them now from whatever is most easily available...1970's springs meant for 7 pounds of pressure.
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Old 08-30-2017, 07:41 AM   #12
markdtn
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Default Re: 8BA Fuel pump quandry

I did my best to measure and I am pretty close to that .2". It's not easy with balancing and keeping the stand surface parallel to the intake. I put it all back together and it seems OK. I ran it a while but it got dark so I had to quit. I am getting my painted sheetmetal back this week. If all goes well I will take it to the Pioneer Days in Eagleville TN next weekend for it's maiden appearance.

I just do not want to use a regulator. Should not have to have one. I will search for a softer spring if needed. Right now I have one of those plastic fuel filters and it is not quite staying full so I do not believe pressure is excessive.

Thank you to all that responded!
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