Had 169,000 miles on the engine and it was getting hard to start so I checked the fuel pressure and it was about 30 psi. I replaced the filter and installed a Walbro pump in the tank. Turned the key on and it wouldn't hold pressure for more than a second or two but with the engine running it was about 40 psi so I put a new pressure regulator in and the same thing happened. I was wondering if the problem was the Walbro pump not having a one way valve to stop the pressure from returning to the tank. Anyone else run into this problem? Now I just have to turn the key on wait a second for the pump to build pressure and it starts but if you just try and start it like most other people do it takes a few seconds of cranking to start.
Edited by: cabits

I haven''t tried one of those pumps, but some pumps are like that. What motor and year is it?

May be a bad fuel pressure regulator or check valve on the fuel pump.