I can't figure this out. Few weeks ago the engine started stumbling at acceleration, and it sounded liker a fuel issue so I cleaned the filter. I have an inline pump and two filters, one between the pump and the tank and one between the pump and injectors. I cleaned the one between the pump and tank (russel 40 micron cleanable filter) and everything ran great for a week. It starts to stumble again so I disconnected the both filters, replaced the main filter and inspected the Russel. It was still okay. Yesturday its runs great all day, then in the evening after its ciold I can't get it started. I check the fuel pressure at the rail and note 42 psi when the key is on, and the pump primes, but then falls to zero when I'm cranking. I figured the pump might be cavitating, and maybe its a result of the plugged filter. I forgot to mention that for a few months the pump was screaming and I could figure out why, and then after I cleaned the filter it quietened down like a church mouse. Anyway, I'm thinking that its an issue with the actual pump, so I changed it. The new pump is a Holley, and I noted that at the rail I only get 37 psi rather than the 42 from the carter pump. It took me a few minutes of cranking before it finally ignited, but then ran great for the rest of the night. This morning it won't go. Here are the symptoms: rail pressure during the prime is still 37 (not sure if that makes a difference), no ignition kick at all.

Any ideas??

Thanks in advance