Hard starting Cherokee

Mike, I pulled the old pump apart when I swapped it out in the 88. In that one, the drainback was essentially a ball that the pump pressure opened with a small spring to close it when pressure was off from the pump. It was in a housing that was inserted between the outlet of the pump and the outlet feed line.

The regulator is supposed to keep the pressure up so that it closes off the return line when pressure drops below 30 pounds but reading the MPI manual for the 88, it looks like the limit on that is closer to 20 pounds - the MPI manual calls for no less than 19 pounds in the fuel rail after 10 minutes bleed time.

The new pump I put in (universal replacement type) had the check valve inside the pump housing cap so I put the old external check valve on as well. I the process, I found a universal check valve for drainback at the parts house. The (old) counter guy said it was for GM cars and went on the inlet side of the fuel filter. He carried it for pumps that worked but bleed back - much cheaper and easier than dropping the tank and replacing a perfectly good pump jsut because of a $0.25 ball valve! FWIW, I just checked mine after setting for 2 days - 14 pounds.

-- Will Honea