No, the bleeding down to 12 PSI was intentional per the testing instructions in the 96+ fuel system troubleshooting document. I did that, it wasn't something that happened on its' own. I don't suspect a distributor problem as the driveability issue goes away after driving the car for a while, which doesn't make sense. I'm suspecting a problem with the CSFI poppets, I'm trying to confirm/deny this so I know whether or not replacing the spider injector is necessary.

 

Condensation on the under side of the distributor cap causes crossfire in the cap. It's usually caused by the vents in the distributor base being restricted. As the vehicle is driven, heat from the engine evaporates the condensation and the problem clears up. Make sure the vents are clear and the PCV system is working properly. Also, be sure to use silicone dielectric grease on the terminals inside the cap. Incorrect camshaft retard can also contribute to crossfire in the cap.

 

OK, where are these vents? On the part of the distributor the cap attaches to, or on the part that goes into the engine? And as far as caps/rotors are concerned, I've ran AC Delco, Napa Echlin, and Accel. I prefer caps/rotors with brass contacts over the aluminum ones, which is why I don't typically use the AC Delco ones (That's what was on the car when I bought it).

 

Remove the cap & look on the bottom of the distributor housing, (the part that the CMP sensor mounts to). There are two slits on the new style housings and two round holes on the old style. If it has the slits, make sure they are clear. If it has holes, there is a screen in each hole. GM has a TSB that instructs you to completely remove the screens and discard them. They are about 3/16" in diameter. The brand of cap that you use is up to you: past experience on customers vehicles has showed me that the best performance/longevity/mileage comes from an AC Delco cap. What ever one you use, make sure you put a dab of silicone dielectric grease on the terminals inside the cap.

 

I pulled the cap and rotor today. I saw 2 round holes, one near the module the electrical connector plugs in, and another one 180 degrees away from it. Neither one looked blocked, and I didn't see any screens in them. The cap and rotor still looked fine to me (as they should, they were put on < 5,000 miles ago trying to fix this same problem.)

Also, the problem has gotten worse, today the car was backfiring as I drove it for about the first 5-8 minutes unless I got on the gas hard. Any more ideas? Sensors to check, etc.? And when I opened the hood to pull the distributor cap (after the car had been sitting about 3 hours), I smelled fuel in the engine compartment.

 

Distributor sounds fine.

You mentioned in your first post that it got worse the longer it sat, and that it seemed to smooth out after driving for a bit... and now you smell fuel. Just for grins & giggles, make sure the fuel filter is not restricted, then connect the fuel pressure tester again. Cycle the key a few times to build pressure. See what the fuel pressure is 10 minutes after the pump shuts off. It's possible for a poppet to stick open at times, so repeat this two or three times to get a bigger picture of what's going on, (give it a chance to screw up). One, (or more) of the poppets might be sticking open causing the cylinder to flood. Checking leakdown like this is only as good as the check valve in the fuel pump. If it leaks, fuel pressure will leak down also and you won't know what's leaking. The pump should actually be isolated from the injectors when checking for injector and/or poppet leakdown.

 

Would having just replaced the filter (Late December, about 500 miles ago) be a good indication that the filter isn't restricted? Or is there something else I should be checking, like checking for kinks in a line? I don't really know how to examine a fuel filter other than pulling it and seeing if sediment comes out with the gasoline that's inside it.

 

If you get a load of crappy fuel, it can plug up a filter in a matter of a few miles. Unfortunately the only way to know for sure is pull it off and dump it out. You should be able to blow through it very easily. A kinked fuel pressure line would have the same result as a restricted filter, although that's not likely due to the way the lines are routed.

 

well i have a 96 s10 and a 97 blazer, the s10 for sure has a bad injector assembly the lines are cracked and leaking its side effects include; rough starts that sometimes include engine shutdown, random misfire, the occasional p0300, horrible fuel millage, and i believe the first clue that i didnt think of untill several months later was a clogged catalytic converter. the blazer however has the misfire issue im pretty sure is the cap and rotor, got the new ones just aint got a chance to put them on yet. i think what im gonna do to solve the injector issue is but the updated MFI and put that in the blazer which i am keeping and have started upgrading, then take the old injector from the blazer which is still good and put it in the s10

to check it the injector lines are cracked just pull off the intake tubes, look down in the throttle body fully opened with a flash light and check for raw fuel, will most likely be black due to dirt and carbon build up

 

Hello
I replaced the crappy ols style fuel injection system with poppet valves.
With the new style, fuel injectors at each cylinder.
cured my idle problems, lot more power, no stalling,
also increase in mpg by 1 to 2 mpg's.
Yep ditch that old system.
Took me 3 hours to do.