Dropping fuel pressure at WOT

[retorq]

That's what mine looked like ...

 

[gpracer1]

It does it no matter what the level. I topped it off Monday when it did it first, and it did it less severe today with the tank at half. It seems to do it though at the end of my 1.25 hr. commute and less time if I am sitting in traffic. Could this be the fuel pump harness heating up and impeding voltage?



Have a NIB one on my passenger seat waiting to go in this afternoon. I will see if the situation improves after this.

 

[BluHoe96]

I know updates have slowed down because of work. Hopefully I can get a chance to do the fuel filter this afternoon. One thing I have noticed though is that I am consistently getting the sputtering/stalling about 45 min into my hwy. drive. If I could hook up a fuel pressure gauge while doing hwy. speeds I'd be set.

We'll see how things pan out after the fuel filter install...

 

[BluHoe96]

Throttle response has change for the BETTER with change of the fuel filter. Engine performance has definitely improved. I can goose the throttle now with no sputtering. However I think I still have a problem.

When I goose the throttle from cruising at 30 mph and do a 2nd gear drop the truck just hangs up and hangs out between 3-4 rpm and goes nowhere. Again tranny was just rebuilt so don't think it is that. I guess; 1) I have to see how the truck performs on my commute to work tomorrow and ; 2) I have to measure the fuel pressure on that 2nd gear drop I experience the hang up at. Hopefully I can do this during the week if I have time.

 

[BluHoe96]

Still doing the same thing sputtering after a long commute. This time though after the ff change had enough power to not allow the truck to go in limp mode. This morning got P0420 after just getting going? How can i confirm whether my cats are good?

 

[BluHoe96]

Ok! So yes, things are leaning towards a weak fuel pump! I managed to screw on the fp gauge when the truck was sputtering on the way to work. This is what I found:



That was at idle! For some reason my iphone was having problems taking video, but at half throttle I was dipping to about 15 or so psi (its hard to read in the dark and through the windshield where the pump was hanging out the hood.) These pressures are not apparent when the truck is running fine. They are at 60-62 psi at idle and 15-25 at throttle. Could it be the harness heating up over time and a voltage loss feeding the pump? Is it common for a pump to progressively go bad after time spent being on? What are the fuel pressures supposed to be at different conditions other than idle?

I mentioned earlier I did the pump already a little over a year ago. I DON'T WANT TO DO THIS AGAIN! I managed to get an Airtex fuel pump that also comes with the harness pigtail. It was considered Advanced Auto Parts' Premium Brand. Is this any good or will it crap on me in another two years? Should I just wait a couple days and order the AC Delco? What is a good fuel pump that people have had experience with.

BTW, at the fuel relay during the low fp condition, this was my voltage:

 

[AtomicHoe094]

walbaro is a good one but im not sure if they make one for are trucks thats drop in..

ACdelco would be the logic and best way to go, buy it on ebay. or just buy a really nice warranty on the new one at the parts store, these pumps tend to go A LOT!

 

[BluHoe96]

What is it that makes the pumps go? Why are these any different from other pumps? Is it the vendors for our vehicles? If I get a walbro how did you make it fit in the sender? Is it fatter or skinnier than a stock pump?

 

[gpracer1]

Well its either the pump or the regulator (which is in the manifold and part of the spider). Either one sucks to replace.

 

[retorq]

When I did my pump replacment the pump was different (longer I think) and I hacked up my bucket like most of the LS based guys that run Walbros did ... if you do a search at performancetrucks you'll find a few pics ...