The Stovebolt Site Forums The Shop Area Engine Shop Symptoms of a bad fuel pump? - UPDATE

I first had 2 Airtex pumps fail on my F150 about 10 years ago. They failed in quick succession both with a torn diaphragm. I thought something must be wrong with my fuel pump eccentric.

Anyway, I replaced it with a Precision pump and that one is still working,

In the interim I had an Airtex pump fail on my Cadillac. I asked among my Cadillac friends who all said they were well known for having the inlet and outlet valves jump out of their seats because they were never staked at the factory.

I opened up two of them and sure enough, the problem was valves out of position. I reinstalled the valves with Red Threadlocker and staked them as the original FSM says to do.

I didn't even have to take the pump off the engine to do one of them.

You can see one of the valves just laying on top of the diaphragm where it fell out. In the last pic I took a punch staked the perimeter of the valve to keep it from coming out again.

You might find a similar problem with some of the new pumps being sold today for AD trucks. Since the original ones are sometimes hard to come by, you might have to repair one of the crappy new ones.