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-   1957 To 1969 Full Size Fords - General Technical Discussion (http://squarebirds.org/vbulletin/forumdisplay.php?f=23)
-   -   Fuel pump vacuum (http://squarebirds.org/vbulletin/showthread.php?t=20909)

Hazegray53 09-19-2016 11:30 PM

Fuel pump vacuum
If I'm not using the vacuum connections on top of the fuel pump do they need to be capped for the pump to work?

Joe Johnston 09-20-2016 07:53 AM

No "need" to

Hazegray53 09-20-2016 09:30 PM

Well I can't get fuel to the pump. This pump worked before I took everything apart. I installed a filter in line before the pump, just in case, along with the filter at the carb. There was also some pressure built up in the gas tank when I added more fuel this afternoon. What do I do next?

Joe Johnston 09-21-2016 09:03 AM


Well I can't get fuel to the pump
This is not the pump's fault and you must have fuel to it for it to pump to the carb. You will need to check the following:
1) Since it has been apart the internals MAY have an air leak and/or not assembled properly which is not creating enough suction to draw fuel to it.
2) The pump may not be installed properly as the lever can be installed on top of the camshaft lobe instead of under it. (Never seen it happen but have only heard it is possible.)
3) The "pre-filter" you installed may be restricting the flow. It may be directional and in backwards and stopping the flow. For testing purposes, I would remove it until after you get things running well and then re-install if you want.
4) Check for air leaks at all the fittings in the fuel lines to the pump.
5) If you have a Mity-Vac hand operated vacuum pump try and draw gas through the lines to the pump. Inexpensive versions are available at Harbor Freight stores if you don't have one and Autozone may even have one in their "loaner" tool selection.
6) Pressure in the tank can be caused by temperature changes. At this point it would have been a good thing to help push gas to the pump, BUT your tank should not be pressurized and you may have a problem in the venting or the cap itself. No more than the level would drop from getting gas to the pump, I doubt that improper venting is the problem preventing getting gas to the pump, but the cause of pressurization must be eliminated.
7) By today's standards, these pumps are a bit weak and they have the disadvantage of having to suck fuel all the way from the tank, instead of pushing it as our fuel injected cars do. They operate at about 5 pounds pressure at the carb. That said they have worked quite well and dependably in millions of cars for who knows how many millions of miles and hours.
There is a cause, just have to do a bit of checking to find it.

Joe Johnston 09-21-2016 10:07 AM

forgot to add - do you have the fuel line FROM the tank to the INPUT port on the pump?

jopizz 09-21-2016 11:25 AM

Very often the car can't crank fast enough to draw the fuel from the tank when it's dry. Pour some gas into the carburetor so the car runs for a few seconds. If that doesn't work do as Joe mentioned and try to draw fuel from the tank using a vacuum pump. You can also try pouring gas into the pump to prime it. Make sure that your gas cap is vented.


Hazegray53 09-21-2016 03:51 PM

Thanks for all the great info!

If I did put the pump together properly and all the seals are good, would I be able to feel the vacuum with a finger while turning it over?

I'm sure I got the lever under the cam. It was a pain getting it bolted up while having the arm pressed against the cam lobe.

I probably do need a new gas cap. I don't think the one I have is vented. Have to check when I get home.

I believe I have the lines connected properly. There's a hardline from the pump to the carb. The other port has a nipple screwed in with a rubber line connected from there to the main hardline going back to the tank.

jopizz 09-21-2016 04:15 PM

When you move the lever you should hear it pumping. When you put your finger over the inlet you should feel vacuum.


Hazegray53 09-22-2016 12:38 AM

My gas cap does seem to be vented. Apparently not enough to relieve pressure in the tank. There was a lot of pressure built up again this afternoon.

I was able to feel some vacuum at the pump input. Still not sure if it's enough and it doesn't seem to be pushing fuel to the carb. I was able to create a vacuum to get fuel from the tank to the pump to give it some help. Need to troubleshoot that some more.

I filled the bowl in the carb and was able to get it to run for about 15 seconds but it spits and sputters and shuts down. I'm sure I need to get the carb adjusted properly but have no real experience in that. Any help would be appreciated on that as well.

jopizz 09-22-2016 10:27 AM

One thing you can try is disconnecting the line that goes to the tank and run a short line to a gas can or any container you can put some gas in. If it won't push or suck gas from a short distance then it's not going to work all the way to the tank. As for your carburetor has it been rebuilt. If it's the original it at least needs to be cleaned out and a new rebuild kit installed.


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