I have a 1999 blazer is there a crankshaft sensor and also a camshaft sensor on it?? I have the terrible p0300 code, was wondering if replacing the crankshaft sensor is would be of help,

 

Sure is, in both cases. The CKP (crankshaft position) sensor is located on the timing chain cover near the harmonic balancer while the CMP (camshaft position) sensor is located under the rotor in the distributor.

You could throw parts at it in hopes of curing the problem by luck or you could look through the information in the P0300 post in the DTC section as well as searching for P0300 to find the rather lengthy thread which sorts through a lot of the causes.

 

I have 1999 Blazer 4.3 been fighting P0300 code since last october,borrowed a code scanner here is the data Calc load 30.1 Coolant 187 ST FTRM1% -7.8 LT FTRM1% 12.4 ST FTRM2% -0.7 LT FTRM2% 8.5 Map (in.hg) 21.5 RPM 2245 Veh speed 64 MAF (1b/min) 5.991 ABSLT TPS 31.3 Can someone figure out what is wrong with it from this info. Thanks Dale

 

Other than bank 1 running quite a bit more rich than bank 2 for some reason (FTRM1% LT -7.8 means the PCM is trying to lean out the mixture).

Have you had a read through the threads below:
P0300 - Random/Multiple Cylinder Misfire Detected
The dreaded P0300 CAUTION LONG POST

*Merging with your post from January of 2009*

 

So far I have about a $1000.00 of parts into it with me doing the labor, have read the info on the P0300 code,I believe it is fatal and close to uncurable.

 

I keep harping on this because I had it happen. Did you do the fuel pressure check? It's in the DIY section. It's an easy check. If you take out the air meter valve on the intake plenum and look in on the intake see if the driver side is crappy while the passenger side is clean. It's a $45 part and 1/2 hour fix. Fixed mine. I had P0300 and the rich on bank one codes. Now it runs smooth and my mpg is coming up.

 

There is no "air meter valve" (aka manifold tuning valve) on the 96+ SCFI motor.

To the OP, how about you run down through what you have replaced and why.

 

everything i put on it for parts i did only for the reason of hoping the problem would go away.first i did delco plugs,wires,fuel filter, BWD brand cap and rotor, then i did delco injectors, then i did a map sensor, then i did a iat sensor, then the intake was leaking antifreeze so i did intake gaskets and a coolant temp sensor while the antifreesze was drained. then did a relearn on the computer. If i was even a tooth off with putting the distributor back in it would be tough to even get it to start wouldnt it. I drive it every day it starts right up, hesitates most of the time when taking off but not always, with the cruise on going down the interstate when you go down a hill it seems like it has a hard time figuring out the correct amount of fuel or spark it should have, it jerks slightly,then trips the check engine light, have checked fuel pressure several times 59 psi,then 55 psi while running.

 

BINGO! Key on, engine off, fuel pump running, pressure must be 60psi to 66psi and remain above 55psi for 3 to 5 minutes after the pump shuts off.

 

my chilton manual says 55-61psi then decrease by 3 to 10 psi at idle 1999 blazer csefi fuel injection