ok I was driving down the highway lost a bit of power then slowed down and died. after that its hard starting and once it does start it runs terrible like its only firing on 3 cylinders. the cat converter is making noises so I thought well cats clogged. I popped all three pre cat O2 sensors and still runs terrible. it will rev to 5 grand no problem. after it runs for a bit and I pop the breather off the throttle body I get a bunch of white gas smelling vapor when engine is off. seems to only start when you give it gas while starting. sometimes it will start on its own but have to keep foot on gas for awhile before it will run on its own but very bad.


what ive checked and done so far


fuel pressure key on engine off 60psi and holds for over ten min without a drop in psi.


all sensors like tps and temp sensors read correctly on scan tool
full tune up all delco parts. didn't change anything, all plugs looked black
cleaned mass air flow.
getting p0300, mass air flow, and sometimes a map sensor code. mass air flow code comes on randomly.
new map sensor
unplugged mass air flow, still same
both bank o2 sensors running full rich .9 and above
both short term fuel trims are at -30.5% that's a negative 30%
mass air flow sensor seems to read correctly on scan tool. low number at idle and increases when giving it gas.
popped the throttle body off and bunch of gold spots indicating a fuel leak near the back of the plenum. but fuel pressure is a solid 60psi????


so what do you guys think? I'm going to be removing the plenum tomorrow and just wanted to have some opinions if I don't find a leak.

 

Sounds like both O2 sensors (the first in each bank right off the manifolds) could be bad, or you have lots of un-metered air leaking in from somewhere. Bad intake manifold gasket? Bad throttle body gasket? If you disconnect the radiator fan temporarily, you can use propane gas to detect the leak.

I had the PCV hose become completely disconnected and didn't see short term fuel trims as low as you are describing.

 

Definitely a rich condition, (too much fuel, not enough air, or fuel is not being burned) oxygen sensors and fuel trims agree on that, which totally eliminates a vacuum leak as a possibility. P0300 is usually, not always, caused by a fault in secondary ignition, (plugs, wires, cap, rotor, ignition coil) which would also account for the rich condition, (fuel not being burned). Is the ignition coil or coil wire shorting to ground?

 

the coil has nice blue spark and sparks about an inch away from metal.

 

That's good, but is the spark making it to the plugs? Open the hood when it's dark outside, start it up and watch for stray sparks around the coil, coil wire, plug wires, and plugs. A spray bottle with water helps. Put a mist of water over each item and watch for sparks.


If that checks out OK, try this, then post all 4 readings: https://blazerforum.com/forum/2nd-ge...eakdown-88305/

 

well I got the plenum off and it looks like either number 3 or 5 poppet nozzle was leaking causing fuel to spray all over inside the intake. heavy gold spots in 3 and 5 intake holes. also when I pulled out the spider I have found number 6 poppet melted at the tip.


so looks like new injectors will get this thing going again.

 

Yup, you found the problem. Might oughta do the lines too.

 

what lines? this is the newer style injectors. 97 jimmy. anyway thanks for the input.

 

Sorry, drug malfunction Not paying attention, saw 1995 in your signature Yes injector upgrade is what you need. You'll also need the upgraded bracket, (some injector kits come with it, some don't) and an upper intake gasket set, (plenum gasket).

 

hmm I ordered the injectors off ebay for 175. its the new upgraded ones. but I'm not sure it comes with the new bracket? would I be able to buy that bracket from the parts store. gonna call them tomorrow and see.