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1967 Mustang Convertible
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Discussion Starter · #1 ·
So my car did not want to start. I checked and it seemed fuel was not getting to the carb. So I suspect fuel pump. The fuel pump is only like 2yrs old with 5-6k miles on it. So I remove and if I manually pump I can feel a suction from the inlet good, but I don't feel any air or anything coming out of the outlet?? Almost feel like a little suction. I do feel a little air coming out of the little hole in the picture included. What is this little hole for? Is my test valid and I need a new fuel pump again??

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Best test is with it on the engine, supply connected, outlet before the filter pointed into a jar away from the ignition and carb, ignition disabled, crank the engine and see if gas pulses into the jar.
Maybe your filter is stopped up. Maybe the sock in the tank is plugged. Maybe the needle and seat in the carb are stuck closed. Maybe the float is stuck. Maybe it's outta gas.....
 

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Discussion Starter · #3 ·
Thanks Myfirstcar66. I think I will replace the fuel pump, since further research shows its a weep hole and fuel comes out when the diaphram is leaking. So I don't think air is supposed to be coming out of it when I am testing.
 

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Air will normally get sucked in and pushed out the hole as the diaphragm is moved by the pump lever. It’s a vent hole to make sure atmospheric pressure is acting against the diaphragm, not a weep hole, like a water pump has.

Z

PS don’t be concerned with the vent hole. As mentioned previously, hook up the pump and turn the engine over with the starter. If gas doesn’t come out the exit of the pump you either have a gas line blockage or the pump is bad.
 

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A carbureted engine will start and run on the fuel left in the float bowl, unless enough time has passed that it has evaporated.... and this typically takes weeks. If you drove it within the past couple days and it didn't want to start it's probably NOT the fuel pump.
 
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Best test is with it on the engine, supply connected, outlet before the filter pointed into a jar away from the ignition and carb, ignition disabled, crank the engine and see if gas pulses into the jar.
Maybe your filter is stopped up. Maybe the sock in the tank is plugged. Maybe the needle and seat in the carb are stuck closed. Maybe the float is stuck. Maybe it's outta gas.....
And...do this outside, not in the garage.
 

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Discussion Starter · #7 ·
A carbureted engine will start and run on the fuel left in the float bowl, unless enough time has passed that it has evaporated.... and this typically takes weeks. If you drove it within the past couple days and it didn't want to start it's probably NOT the fuel pump.
Its been over a month since its super hot in Texas. So I filled the bowls and it ran for a few seconds and then stopped running so I know its not an ignition issue. I kept cranking after that and it didn't want to run and nothing spraying into the carb. I haven't had a chance to test putting fuel pump back in an disconnecting from carb to see if it gets to that point or not. Have an edelbrock fuel filter is the only other thing that can be blocking it. Will probably work on it tomorrow. Fuel indicator shows 1/4 tank, I put one of those camera things in gas tank but so hard to tell how much is in there, but there is gas in there. :)
 

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How long did you crank it to try to get fuel up to the carb? When these cars sit for a month or so, the whole fuel line, pump, filter, and bowls can run dry and varnish can stick small parts in the carb. If it ran for a bit when fuel was in the bowls, connect it all and try again.
 

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See how supply line flows fuel to pump. Disconnect supply from pump and you should have a solid stream not a trickle. If it's having to suck fuel because there's not a healthy enough supply flow you'll have repeated pump failures.
 

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First eliminate either fuel line being plugged up. If you do have to replace the pump consider getting the ‘65 pump with its integrated & replaceable fuel filter. Many here on the forum have switched to ‘65 pump.

That arrangement is much better than the ‘66 and subsequent years that use a pump with a much smaller separate inline filter. With the ‘65 pump you won’t need, or want to have, any inline filters.

Z
 
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