I have been running lean lately. It started in Maryland, running 13.2 when normal for me is 12.6-12.8
Last runs here in Florida, I started hitting 14.0 so I am thinking my stock fuel pump with 104k miles is giving up. I ordered another since my fuel gauge acts up when I fill over 3/4 tank, + a new fuel filter. My filter only had 14k but over 4 years or so. I took off the filter and it slipped out of my hand and dropped on the cement. Out pops a rubber o-ring that looks like it is from an injector ??? Not sure how long it has been in there but it was too big to pass thru the hole. That could have been the problem.

Hope to hit the track again soon to see if it starts normal AFR readings !!! I guess I will never know if it was the pump or o-ring blocking gas flow.

 

How did a injector Oring get there? Obviously I doubt you have that answer, but yes weird **** happens....

 

I haven't changed the filter or the injectors since I dropped in the 402 in 2008. Gas lines were new SS so it makes no sense. I am clue-less as usual....lol

 

well, this is a first but now i will be inspecting every fuel filter i ever look at again..lol

hope your mysterious problem is solved now

 

I dont have a filter on my truck there, but was it the O ring for the fuel line that goes on the line for the filter? Did you happen to check your fuel pressure?

 

It's been a while since I did mine but ya isn't there a O-ring that's on the line going into the filter?

 

I have new SS line run from fuel rails to filter (new in 2008). Nothing touched since. Fuel pressure is at 48 @ idle. I have gauge on the firewall.

It was losing pressure at 4k with old pump....down to 42psi. I have the compression fittings with no o-ring by the way. No clue where o-ring came from.
Now my pressure is holding steady at 4k, right at 50psi.

Injector readings are in the 60's at WOT

 

Dumb question you reuse filter? Come off old line?

Edit : never mind you said it's compression now

 

Yeah new lines and filter with new motor in 2008. The Filter I just took off was clean as new, except for o-ring.

 

I went to MIR in November and it would not run lower than 11.3xxx. I ran 6 runs that were all 11.3xx @ 118mph, and all running a little lean. Now I know what was up. Had good air too, about - 7oo DA