I'm helping a friend figure out what's wrong with his 99 silverado 1500 with a 4.3 vortec motor (177000 miles). Ithas a po300 code only. I have a autotap system that I use to see what was wrong. There seems to be a problem with the fuel trim. The short term on bank one was 43% and bank two was between 3-6 %.

The fuel pressure was60 psi with the ignition in the on postion and 55psi running. I don't know alot about this type on motor. I think I remember the fuel pressure regulator was built in to the intakemanifold along with the injectors or poppets as there called.

I told him he couldhave a bad gasket on the intake or there is possibly something wrong with the fuel system inside the intake.

Does anyone have any suggestions about what could be possibly be wrong or is there common problems that occur.

 

Fuel regualtor might be bad. Argon would now how to tell for sure.

 

+or - 43?

 

2000 4.3L Silverado 2WD
I also have get PO300 with rough running.
Started with PO135 also. New O2 on drivers side. Now only PO300.
Replaced all plugs. All three on passenger side looked good.
All three on drivers side where black and sooty.
Checked for spark with timimg light. Looks good for both sides.
I'm guessing fuel problem on drivers side.

Any ideas?

 

Okay, so I have some questions (I am trying to learn) First off what is the code and what does the code PO300 stand for? Second off what is an autotap and what does it do? I am assuming it reads stuff in the truck through some chips where you plug it in?

"There seems to be a problem with the fuel trim. The short term on bank one was 43% and bank two was between 3-6 %." what is the fuel trim? The amount that the fuel injector sprays out of gas at a certain time? what is the short term on bank and what is bank? Thanks much, Tyler!

P.S. I know asking these nooby questions lol makes me seem dumb ect ect, but I know little to nothing about trucks and am not afraid to admit it, but I want to learn more which is why I ask!