In reply to A 401 CJ :
Yup. I have a '74 CJ5 w/a 360. It's a hoot!
OP: As others have said, just test the pump. You can bolt it back on and run it with the outlet into a jar, use vacuum, or just lean into it with the arm pressing on something solid. If there's fuel in it, you'll know quickly if it's pumping.
I just went through a hassle with mechanical fuel pumps for a Chevelle. Went through three pumps (one unknown parts store junk and two NAPA) before I bought a "good" Carter from Summit Racing. To of the pumps leaked externally at the pressed together seam and one knocked badly. The Carter is working well.
That pump looks cleaner than brand new. I would eat off that diaphragm.
Hard to see if there are any cracks in the rubber or anything obvious. There is one spot in the plunger cup that looks suspect, but it's in the steel stamping, not the rubber.
I guess it couldn't hurt to blow some air through the line up to the carb and back to the tank to make sure there isn't an obstruction, but I would write this one down as random pump failure and buy a new one.
Edit to add: Swapping to an electrical pump isn't a hard thing, but also not always more reliable. If you get a good mechanical pump, it will probably outlast the engine, but unless you're buying a big-dollar electric, it won't do the same. The mechanical pump is also a positive displacement thing that will suck air through a line. If you ever run out of fuel, a mechanical will self-prime with just a few more cranks. Electrics can be picky since they are often gerotor pumps that work to push liquid, but they're poor at pushing air. They might require a little help to prime if you run them dry.
That pump looks new. The part that fails is the rubber diaphragm (circle). Based on that, someone was chasing the issue before they sold it. Do you have a vacuum pump? If so put it on the line from the tank, see if it flows from there.
I will ask the one main question, are you sure it has gas in the tank?
In reply to Steve_Jones :
Funny you mention that. As I was digging around the thought occurred to me "could it be out of fuel?". I was 99 percent sure I had filled it but went and got fuel just to be sure. It only took 3 gallons, so it's definitely got enough fuel.
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