2001 blazer, throwing a p0300 code . My question is what should the fuel pressure be at idle. Mine is 48 psi and drops when you apply throttle. I have replace the spider injectors with new updated version. I read somewhere that these new updated injectors could run at a lower pressure but mine seems a little low. System does not leak down and pressure is around 50 psi with switch on and engine not running. So is it time for a new fuel pump and could this be my p0300 problem. New ac delco wires plugs cap and button. Any help would be greatly appreciated .oh distributor crankshaft position sensor and map sensor are all new.

 

Your fuel pressure is too low. It is also tested with the key on vehicle off. Do a quick search here and you will find the acceptable specs for fuel pressure range.

 

Fuel pressure is definitely low. This link will help:
https://blazerforum.com/forum/2nd-ge...eakdown-88305/


If/when the distributor is moved, removed, replaced, or disturbed in any way, camshaft retard needs to be checked and adjusted if necessary using a capable scan tool.


If when the crankshaft position sensor and or timing cover are moved, removed, replaced, or disturbed in any way, the crankshaft position sensor relearn must be performed using a capable scan tool.


All three of these things could be contributing to or causing your P0300.

 

FP way to low, should be at least 50-55 PSI and when you've got the foot on the gas it's 60 PSI

 

Obviously you didn't read the link that was posted above.

 

So after reading the link Captain Hook left I still have a question. With pressure gauge hooked at test port with key on engine not running I get 48 psi. And it don't leak down. If I dead head the line going in the throttle body I should get around 60 psi. I guess what I am asking is what pressure should the regulator hold with no vacuum on the regulator. (Would 48 psi still be low and should I dead head the line and check it also. Sorry for the dumb question just making sure I am looking at it right. Thanks for all your help

 

Yes 48 is to low

 

Thank you

 

All pressure readings are taken with the engine off, (no vacuum applied to the regulator).


If you remove the fuel pressure line from the fuel metering block, and cork the line off: The fuel pressure at the service port must be 73psi to 108psi while the pump is activated. Fuel pressure must remain above 55psi for at least 10 minutes after the pump is deactivated.


NOTE: For obvious safety reasons, this method is NOT recommended due to the high pressure. Use the adapter described in the link.

 

Thanks Captain Hook I reread your link and it helped alot. I was thinking of doing just what you said. Thanks for all your help I'll keep you posted on my findings.