OK, so....I have a gem sitting in the garage. We have become quite good friends last few weeks. Over the course of the past 2 months, it's been missing a little it seemed. Check engine light been on for a long time, random misfire.....
right now, it will start, with the pedal to the floor, and run super crappy (sputter really, not run) for about 30 seconds, engine light will flash a few times, and it will die all the way. While it is running, it will not rev above 1800/2k rpm's.

A few weeks ago, it wouldn't start. Dug around the nets, and clogged up cat kept popping up. Guess what? I took out one of the o2 sensors in the front, and it fired up...sounded fully, but ran, and would run well enough to take the kids to school and whatnot. Took the second one out, ran a little better. SO, I thought i would slice a hole in the exhaust just before the cat, let it breathe a little more, made more of a square, so there was plenty of an outlet for the exhaust, plugged the o2 sensors back in, ran great for a few days, minus having to keep the windows down to avoid all the fumes. Thought to myself the cat musta been plugged, and now it can breathe!! right?? nope.
i cut the cat out, broke exhaust manifold studs in the process of dropping the exhaust...welded in a pipe to take the place of the cat. Now, the truck will not run enough to pull it back into the garage.....up hill drive way of course. disable the neutral safety switch, use the starter in gear to get its way to the garage after a day and a half, and killing one new battery charger....
replaced mass airflow (with new), as it came up as a trouble code on a friends snap on scanner when the truck ran enough to use as my daily transportation, didnt seem to change. at this point, the truck has no clue whats wrong with it, as the codes have been long cleared, after draining and re charging the battery.

So, i go to the basics....
fuel pressure - pump was replaced 14k miles ago, but tested anyhow, and it was a little weak, with bleed down of pressure. trying to pinpoint the pump and avoid the regulator, i put the gauge on the end of the fuel filter. after several primes, it would read -0- pressure!!! (even had the woman get under the truck to watch the dial not move, while the pump buzzed happily away. So, with that, i decided the pump was not performing as it should, weak, and intermittent.... replaced the pump. several trips to several yards, as i broke the first one i found putting it in the truck. i found a roll over truck, figured it was running good enough to get to roll over speeds, might be a winner. it was an aftermarket, had the brand "precision" on the sides...had to change the wiring pigtail on the truck to use it. anyhow, now it has great pressure at spool up, but im watching it bleed down. pull the intake off, sure enough, the regulator is dripping. lucky for me, i grabbed one of them too while i was at the yard. 2, actually...the first replacement leaked as bad as my original, but the second one held tight. thank god. anyhow, i checked the pressure with the upper intake still off, didnt see any injectors leaking....bought a new set of upper gaskets, and put it back together. Still, no awesome running results. pulled 3 plugs, spark looked good....also grabbed a computer from another truck at the junkyard...read lots about how they need to be re flashed...grabbed one out of the same year, same options, and same service tag...truck doesnt run any differently between that and the original....original is whats in there now. i saw people mention the passkey, and this truck has no chip key...tested voltage at the MAF, seemed to pass.
some history, plugs/wires/cap/rotor/coil replaced with high quality stuff, did a/c delco on most. replaced pigtails at MAF and coil....replaced IAC motor....check engine light has been on 99% of the time ive had the truck, which is almost 2 years now. when we got it, the IAC motor was unplugged, but appeared new. (now it has a replacement) somehow, the check engine light went off just before inspections, and last trip i was able to get a 2 year plate sticker.


anyhow, i need this thing to run...ive got lots of time invested in this thing, as well as cash with trying to get it to run...i dont have a scanner outside of an obdII program on my pc (easyobdII i think is the name). i have a few extra o2 sensors laying around, ignition module, MAP sensor....i have never had a car kick my *** like this.

please help!!!

 

I would check out your spider injector assembly. I had a 99 that had cracked and was leaking fuel slighly into harness plug. After a few years had another symtom that ended up being a injector wire that had rubbed on lower intake and was grounding that injector causing a constant pulse off the injector causing a rich condition.

 

is there a good way to test the spider? I was going to buy another one just to "throw" at it from the yard, but they wanted 80$. I really hate throwing parts at cars...
Just on a whim, I went to the garage, left the key in the run position for about 10 minutes....turned it over, and to my surprise, it ran, and even held idle for about 3 and a half minutes, before it konked out on its own. i did not give it any gas at all, until it wouldnt re start by itself, which didnt amount to anything, just cranking on and off til the battery died. I'm going to let it sit for another hour or so while on the medium battery charging setting, and see what happens.

could the short running period mean limp mode made it work? I was trying to find ways to "force"it into limp mode, but no such luck. i really want this thing to run!!!

 

Whenever the fuel system is suspected, the first order of business is to test the fuel pressure and leak down. The details can be found in the Tech Article (DIY) section or through the convenient link in my signature below.

 

^^x2 That was my thought. It would suck to have hacked up the exhaust system (possible causing additional false positive codes) and spent all that money and time to find it was as simple as a clogged fuel filter (probably not that simple, but just sayin). Along with the wealth of information on this site, you could buy a subscription to ALLDATAdiy.com Leading Source of Factory Automotive Repair Information for about $25.00 per year and have the OEM Technical Manual that has trouble-shooting procedures for whatever the symptoms specific to your year and model. But as swartlkk has the fuel leakdown in his signature block, that is step numero uno. Post your results and there are very sharp folks on here that can take you to the next steps. Good luck and let these guys help you by strictly falling the correct troubleshooting steps.

 

I actually have access to the alldata online, but have not found the trouble shooting guide, will dig more tomorrow. (was also hoping to find "normal" values of sensors to compare my running data to also, but I need to learn how to navigate their online info a little better)
I read the fuel flow chart that your link led me to, I will follow it more closely tomorrow. I left the truck alone for about 2 hours, and when I came back home a few minutes ago, the pressure was holding at about 45psi. When the pump spools with the ignition, it spikes at about 68psi, and fluctuates between 65 and 70psi while cranking. (did not get it to run as it did a few hours ago) It does not bleed down right away or quickly at all, though.
When I saw the regulator dripping the other day, I did not physically see any fuel coming from anywhere but the regulator, and after swapping, I spooled the pump several times before being satisfied the leak down issue was gone.

Thanks for the suggestions so far, I'm grateful to have a few more eyes on it!

 

When you log onto Alldata:

Click the link for your vehicle>Click "Sensors and Switches">Click "Sensors and Switches - Powertrain Management">Click "Sensors and Switches - Computers and Control Systems">Click [sensor you want info on]>Click "Description and Operation" (If you click "Specifications" that will give you resistance values).

When you click into "Description and Operation" you should get the info you are looking for on each sensor. It also tells you DTC's that will be set for malfunctions.

EDIT: Every vehicle I have I buy the hard copy dealer Technical Manuals and I also have Alldata. I use the hard copy more than Alldata, but i love the "Search" function in Alldata. Saves a lot time flipping pages when I can just put in "Brakes" and a link to every part of the manuals dealing with brakes pop up. Plus the Service Bulletins in Alldata are kept up to date and I've already found changes that weren't posted in the hard copy TMs.

 

check the screws on the rotor just went through a no start took it to the garage my screws holding the rotor backed off enough to allow the rotor to move and put the timing
out of whack, I have never had this happen before was very suprised , I too was getting a bad cat code and the code has not come back in 2 day's 150km since repaired

 

fuel pressure was at 20psi this morning, after the truck sat for over 12 hours. pump spools, it goes to 68 or so, and i got it to run for another 3 minutes, it was between 60 and 70 the whole time. I tried to rev it up some, but it wasn't having it too much past about 1500rpms, and the pressure didn't drop at all.

So, anyhow, I found the sensor info on alldata that one of you guys thankfully led me to, and it says o2 sensors should be 445mv...figufred I'd try to read the data on it if I could get it to run again. So, I have 2 extra sensors sitting around, I figure I will do some swapping while reading the scanner data. Does not change the values, even when they're unplugged!!!???!!!

Anyhow, very long story made short, I popped the front two o2 sensors out, and wham, the darn thing runs, and will rev to full redline.....ofcourse it is super noisy and smelly in my garage (WITH door open of course)
So....I guess this means my PRE CAT is clogged??????????


Going to move my (cough, cough Corolla) out of the way, and see if I can get the Blazer out for a test drive with both front sensors out. If the darn thing runs well, I will be making another trip to the auto parts store to get another section of pipe, to do more cutting and welding???

Here goes nothing....

 

Sure enough, the truck runs great around the neighborhood....so, I got it back on jack stands, and chopped the pre cat out, sure as heck, it's not allowing any light at all through it. Will make a trip to the auto parts house, buy some pipe and weld it in. Will post results after exhaust is sealed back up