Detroit 60 losing prime

People have been known to throw a rag in a guys fuel tank. Check yours

 

Have you changed the outside filter? The only way to loose prime while driving is plugged filter or sucking air. The check valve is open any time the motor is running. If it is bad you lose prime with the motor off.

 

If you are talking about the Davco filter there is a check valve inside it on the bottom where the fuel lines attach get your model # go to the dealer and get a new one hope this help

 

@NorthernMechanic ...your 2 cents? for whatever its worth??? i know usually . . . but this one, i don't.
sounds like somebody fouled the fuel line (or tank/s) somehow... in some way. your take?
dunno why i bother when i dunno but. . . . stuff gets me thinkin. (kiddos) oops i meant kudos!

 

Did it start happening right after you changed fuel filters? If a gasket or o-ring got pinched or if a filter got loose you could start sucking in air. Cracked/broken fuel pickup tube in tank could do it too. Garbage inside tanks can cause a fuel system blockage as well.

 

I had a 1998 Century, it had the fuel tank shut off valves over the transmission operated via long extension rods that had the handles you controlled right by the drivers door. Over the years the weight of the rods flexing on the valve stems, caused the valve stems to wear letting in air, causing a loss of prime.
Not sure if you have that setup, but worth considering.

 

When running do you see air bubbles in the housing where the filter is?
There is a check valve on the bottom of those units and over time they wear out. Mine did that, you will see real small air bubbles, or shut it off and look to see if there are air bubbles. If so replace that unit with a new one.