There is value in knowing the fuel pressure while the truck is running, especially as it goes from running ok to running crappy but lets start with the basics. What's the pressure at key on, engine off and then what is it ten min later with the engine still off?


George

 

Key on engine off: 38 PSI ( my brother said it was 20 the first time with key on engine off) after he looked at it I cranked it up then switched it off and it was 38

10 minutes key on, not running: 34

10 minutes after running, engine off : about 46 PSI

30 minutes after running engine off: 38 PSI

Edit: lost the little black piece that covers the shrader valve. Where I test it. Does that matter

 

your fuel pressure is too low. Next you need to test it at the output of the fuel filter to cut the problem in half (fuel tank vs plenum).

https://blazerforum.com/forum/2nd-ge...eakdown-88305/


George

 

ok initial pressure was good and after 10 minutes it was good as well, according to the numbers on the post, so it’s inside the engine somewhere

 

38 psi at key on engine off is too low, the engine will not run properly.

George

 

what do you think that could be? I was thinking about buying a fuel pressure regulator and seeing if that changes anything. The spider injectors have been replaced about 6 years ago

 

Also when I was driving to the store and messing around with the OBD tester and this was showing while I was driving.

 

You need to repeat the fuel pressure test at the fuel filter outlet to help narrow down the location of the failure.

Evap system failures are very common and almost never result in engine performance issues, your just destroying the ozone, or so we are told. You need to fix your fuel pressure problem first.

George

 

I wanted to thank you for all the help brother. I finally got tired of messing with it and took it to a shop. They welded a exhaust on it to stop the exhaust leak where I cut the cat off and it runs brand new now!!!! He said where the leak was the O2 sensor was sucking up air and dumping fuel into the engine.

 

Glad your fixed up, thanks for reporting back.

George