Jeff Ford
May 1, 2001

Step By Step

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Before...
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...and After. Hard to believe these are both shots of the same pump, isn’t it?
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The kit is extremely complete. Since AMK is the place where you get all your correct fasteners, the new screws that come with the kit are shiny and fresh.
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When disassembling the pump, take note of where the fuel line sits on the upper plate (arrow). Otherwise, you may end up redoing the bowl two or more times.
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Separate the fuel bowl using two screws inside the upper bowl. Once again, note where the inlet sits. Though there are only two ways to reinstall this lower piece, it can still be very frustrating to have to tear into the pump again.
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With an ear trapped in a vise, remove the stop plug from the end of the dowel pin sleeve. This will allow for the removal of the dowel pin that holds the actuator arm. As near as we can tell, the only thing that changed on X pumps was the actuator arm itself. This was, of course, different among the different engines.
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From what we can tell, this is the source of our difficulties. The main valve diaphragm has developed a crack near the metal plunger—not an uncommon problem, particularly on an engine that sits up a lot.
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Carefully pop the spring out the pump as shown. Don’t let this little piece go flying; it isn’t part of the kit.
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After the spring is removed, press on the main diaphragm as shown and remove the pin through the hole where the plug had been.
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The actuator gets some grease, as does the receiver; we also recommend greasing the pin. In order to have a good-looking pump, you should beadblast the case parts. Make sure you remove all the glass beads from the pump parts with compressed air.
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Reassemble the upper portion of the pump by reversing your procedures. Use, a base of OEM Paints’ Aluma Dust, then follow that with a dustcoat of Fast Cast to achieve an accurate cast-aluminum look.
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After you have inserted the spring retainer, reinsert the spring. It will be more difficult to reinsert it than it was to remove it.
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Stake the aluminum retainer cap to the housing using a punch. Go slowly because the tabs on the housing can break.
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The fuel diaphragms have to be tapped into place using a 7/16 socket. Work slowly and evenly so that the part is set flush. Remember, two of the fuel diaphragms go on the side shown, and the other single diaphragm goes on the opposite side.
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Install the base to the upper pump and the diaphragm. Pressure will need to be applied to the pump halves to make sure the screws are started evenly.
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You should now have a like-new X pump that will provide hours of faithful service. Of course, you’ll also be able to rebuild it if the need should ever arise again.

If you're lucky enough to have an original Carter X fuel pump on your car, you're truly among the elite in the Mustang world. Why, you ask? Because the X pump was used only on the Boss 302 and 429, the 428 and 429 Cobra Jets, and the Super Cobra Jet. Today these pumps bring very good money, especially if someone needs this piece to finish off his or her vintage performance restoration.

In his recent purchase of a 429 SCJ Mach 1, Bob Myhrer got one of these pumps. Problem was, it was leaking badly--the sign of a ruptured diaphragm. Fortunately for Bob, AMK carries a repair kit that can fix up the old X good as new.