Fuel Pump Question (1 Viewer)

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Nov 29, 2005
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I removed my 1977 FJ40 mechanical fuel pump for a cleaning and noticed that there was a small hex screw on one side of the lower body and not the other. There is a threaded hole there so I am guessing one fell out. The fuel pump is a "Nikki".

What purpose do these screws serve and are they both necessary?
 
The side towards the rear of the vehicle has a hex screw. The side towards the front does not.

Should I chase down a hex screw or not worry about it?
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This is an air pressure equalization hole. If the pump wears out it also acts as a weep hole an gas runs out and smells the FJ up real nice, letting u know there is something wrong under the hood.

...
 
Thanks, I'll remove it.

I wonder why the holes are threaded. Another great mystery.
 
There has to be a reason there is a screw there. Maybe it keeps fuel from exiting the wrong place. Maybe it was desiged for more than one vehicle in mind so sides might be different.

If it's working, and there is another weep hole already what is the advantage of having two.

If it aint broke don't fix it.
 

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