Knock knock, who's there? Knock sensor!

[Jdeshler]

I have an interesting issue with my knock sensors tripping my timing.. They set the light off with no other issues over 1/4 of a tank of fuel. When I go under 1/4 a tank I loose massive amounts of power until the sensors trip the timing which leads to a 40 mph top speed. I replaced the knock sensors about 2 years ago and the fuel pump last year (put an AC Delco pump in the original sending unit). The problem is so persistent that I bought a Bluetooth OBD scanner to clear the codes if my fuel gets too low. It also surges while idling with low fuel.

Now for my beliefs..

Is it possible for the pump to be sucking air at low fuel levels causing my hellish conditions but just enough to only make it run bad? I'm certain the performance issues are from the fuel pump

01 Yukon
5.3
320k miles

 

[MadDogDelpho]

320k? Hot damn! After that long I wouldn't be surprised if your fuel pump was starting to go

 

[HiHoeSilver]

320k? Hot damn! After that long I wouldn't be surprised if your fuel pump was starting to go

Said he put a new one in last year...

 

[MadDogDelpho]

Damn I must be blind

 

[Jdeshler]

Damn I must be blind

Lol. It's cool brother, it was a lengthy post.. I'm gonna pull the sending unit again and see if there is anything obvious. I just wanted to see if anyone else has seen this

 

[Jdeshler]

Went into the sending unit again and found the rubber seal on the foot of the fuel pump was cracked. That wasn't letting it pull the fuel past the little rubber baffle in the sock filter so I just pulled it out of the filter and that eliminated the surge and low power under 1/4 a tank. It also keeps the Knock sensor from tripping the ses because it's getting fuel.. I just have the massive bog at all fuel levels when I first jab it.. I have scrubbed the throttle body(Sumbitch was dirty) and the mass air flow sensor.. I am suspecting it's either a bad fuel rail regulator or dirty injectors.. I am getting an 02 sensor code so they will be getting changed because they never have..

The search continues