Hello folks. I'm new here, just bought a chevy truck a few months ago. It ran when I bought it but after the first day it wouldn't start and hasn't since. I changed plugs & wires, and air filter. It has spark. The plugs smelled like old gas and were fouled a bit. So next I bought a pressure gauge and screwed it onto the schrader value and cranked it over: Fuel pressure

My question is could this be a weak/dying pump, malfunctioning injectors, a faulty fuel regulator or? Any advice or suggestions would be greatly appreciated. Thank you.

 

Okay, so I cleaned the mass airflow sensor, replaced the fuel pump (delphi) and the fuel filter. Charged up the battery and tried to start it up. This is a video of cranking it: Cranking engine

It makes that noise now where it didn't before. Can anybody help me?

 

I thought maybe the sound was from the new pump making better pressure causing a faulted fuel pressure regulator to fail, causing a leak so I pulled the upper intake and replaced that with a new one. Now the sound is much worse. Fluttery noise video

What could be causing this noise?

I also did a new cap and rotor because it seemed to have weak spark, and the cap was a bit corroded. Could this also be a timing issue somehow?

 

Ive got a 1998 Chevy K-1500. Without enough fuel pressure your injectors wont work properly. I cant see your fuel pressure gauge very well but its not steady. After 24 years the fuel pump might be ready to be replaced.

 

Thank you for the reply. I replaced the fuel pump already and it improved the pressure but started making a fluttering noise around the central injector assembly. I replaced the fuel pressure regulator thinking that was the problem but the noise became worse. Tomorrow I will do another pressure test and video it better to show you. Thanks.

 

get some sea foam into tank and pray!

 

I'm thinking fouled injectors myself.

 

Alright, here's a better video;Pressure gauge and Noisy

 

Should be running a 55 PSI (58 PSI really, to 62 PS!. If you've fouled injectors it wont matter
It's one reason GM dumped the old injectors to the new style in 2000 or 2002, about the time the
5.3 liter went into production.

 

It's a brand new delphi pump, maybe a ground issue? ugh.
The injectors are upgraded to mpfi by the previous owner, does that make a difference? What do you think that sound is?