1991 ZR1 Restore - Help!

[kapkanimd]

Hi everyone,

I picked up a non-running (had known bad fuel pumps) '91 ZR1 with 56k miles on it as a project to restore.

Here is what I have done so far:
- 2 new Suburban Fuel pumps & fuel filter
- new fuel pressure regulator & injectors
- all new coils, spark plugs, & wires
- new belt and belt tensioner

- rebuilt damaged vacuum system (tested now working)
- cleaned up plenum, injector housing, throttle body, starter, etc. & replaced gaskets
- new calipers, brake hoses all around, & brake fluid (rotors were turned)
- flushed clutch fluid (no pressure when I got it)
- new K&N air filter
- replaced oil & filter, trans oil, and differential oil
- new battery

After finishing, the car cranked right up on first try. It ran rough, and would cut off randomly but would restart right away. After a few minutes, everything smoothed out and it would idle perfectly up to temperature. I did notice that the vacuum pump would now start running constantly (which was frustrating) so I new something was now leaking, but it still ran.

The next day, I started it up, ran/idled perfectly up to temperature. A few hours later, went to start it, and now it is just cranking but will not start/run! I lifted up the plenum, found & fixed the vacuum leak, and sealed it back up. Still no start!

I checked fuel pump fuses, jumped the fuel pump to hear it run, and used my MT2500 - everything checked out as normal. Next step is get a fuel pressure gauge, but not sure why fuel would all the sudden be an issue.

Any other thoughts? Things I should check? If I need to I can pull a plug to check for spark, but working on it alone and will have to wait for help.

Thank you in advance!!