2004 Trailblazer 4.2l got it for free and the PO said it just died one day and he never got it fixed. He also said that he might have gapped the plugs wrong. He said he got iridium plugs but I thought you were not supposed to gap iridium plugs? Well I figured out it needed a fuel pump first and after installing it I got the truck to fire up. Well it runs like crap. The only code I'm getting is a p0300. While it tries to idle the SES light starts to blink but if you press the accelerator pedal just a little bit the engine will rev up to 3300 slowly and the light stops blinking and stays on. I have a scanner that shows live data and the throttle position won't go past 33.7% even though I have the pedal to the floor with the engine trying to stay running. When the engine dies the throttle position will show fully open with the pedal pressed to the floor. But when it's released the throttle position says its open 12%. I will need someone to help me see if the throttle plate is actually opening and closing completely. Another thing I forgot to mention is when I first got it I put in a new battery and ran the codes and it came back with TPS and APPS codes. But after the fuel pump was installed I never got those codes again. So today I'm going to check the coils, boots, plugs and wiring and if I can't find anything there then I'm going to check the injectors. What else should I be checking?? If I can't find anything then I'll try a compression test and leak down test.

Old fuel pump clearly showing a internal plastic line that's broken.

Fuel pump buried in mud.

Inside of the tank with the pump strainer disintegrated and the missing piece of fuel line from the old pump.

I wasn't surprised to find this! Plastic welded it back together now it's good as new.

Old fuel pump freed from it's mud prison!! It must have been changed before because it's a Bosch pump.