No start 96 W Astro 196,000 rebuilt at 160,000 HELP!!!

[Mickedy]

Hi guys,
I've been looking all over for the solution to my no-start problem on this Astro. I've read quite a bit about the fuel system and I'm wondering if my CSFI injection system has gone bad or if it's possibly just dirty poppets. Can you help me out?
So far I've replaced the fuel pump and filter and I'm getting and holding 60 lbs of pressure to the injector unit. I've checked all the fuses and relays and everything's good. I removed the plenum for a visual inspection and everything "looks" fine. While I had the plenum off I checked the regulator and it seems to be working good too. I'm getting good spark and good cranking power. I tested the injector unit for a pulse with a 12v light and each set of wires pulses when I crank. The voltage there goes down from 12v with the key to 10v while cranking.
I had to replace the fuel pump earlier this year on the side of the highway and the OEM I replaced it with sounded very loud from the start, so when the car refused to start this time, I was expecting it to be the pump. I guess not.
Two days before the no start condition, the motor died on a busy highway (never want that to happen again!). I couldn't hear the loud noise from the pump so I adjusted the connection to the pump inside the tank. I saw some melted plastic on the connection.... not so comforting. I also found a burnt ECM fuse under the hood and replaced that. Worked fine for the rest of the day.
The day before no-start, it started and ran really rough. Started it again and ran the same for about 10 minutes. Check engine light came on and started flashing once I accelerated. It calmed down before I could get a scanner to it and the scanner read a PO300. Ran fine the rest of the day.
Are there any other tests I can run? Is there a way to clean the poppets without the car running? Can I soak them in something? Could it be an electrical problem? Any help on this will be very appreciated! I'm a volunteer youth counselor here in Mexico working with a missionary youth group - not really a mechanic. Thanks for your time and God bless!

[old_master]

P0300 is usually caused by secondary ignition faults including plugs, wires, cap, rotor and ignition coil. Try spraying a fine mist of water on those parts with the engine running. If you do it after dark, you'll see a light show where the problem is.

[Mickedy]

Thanks, Old Master -I'll be sure to try that out as soon as I get it started. Or would trying while cranking work? If you have any ideas why it won't start, please let me know. Thanks again!

[old_master]

Sorry, missed that part Try it while cranking, it will be a little more difficult to notice arcing, but not impossible. Also, try a shot of carb cleaner in the air inlet tube. If it runs momentarily, we need to go back to fuel system diagnosis. Post your results.

[Mickedy]

Don't notice any arcing - thanks for the suggestion though. The van will burn the carb cleaner - got a couple back-fires the second time trying. Back to the fuel system then, Old Master? I just tried cranking it yesterday with 68 lbs of pressure and it still won't start. Thinking of taking the CSFI unit out and somehow cleaning it manually - what do you think?

[old_master]

Proper diagnosis always saves time and money, hold off on any repairs or part replacement until you're certain what the problem is. With the key on and the engine off, (fuel pump running), pressure should be 60 to 66psi. After the pump stops running, the pressure must remain above 55psi for several minutes. 68psi indicates a problem with either the fuel pressure regulator being set too high, (not adjustable) or a restriction in the fuel return line. Check fuel pressure and leakdown again and post your results.