I was going to ask - after I re-read this post I realized there was no way to test this under load, otherwise I would run into the same issue I had the first time with the 'governor' kicking in. Hmmm

Highhorse isn't making a bad suggestion with buying the scanner, just trying to avoid spending that kind of coin until I've done all of the other requite troubleshooting.

 

I told you how to test it under load, back in post #3.

The scanner tells you nothing about fuel pressure, as it is not a parameter that is measured by OBD II.

 

True, they don't show pressure, but they can read fuel trim which is essential. If your O2 sensor is telling the computer to put too much/little fuel and the pump is doing what the computer is telling it, you'll know. You'll have a reading of the balances and if the pump is providing what the O2 sensor is reporting.
I'm not saying anything against your post Mark, I agree and your correct, but the more info, the better diagnostic is my point.
This simple video shows a real good explanation of the need for proper fuel trim...

 

Thanks guys, you've both been super helpful to this point and it's much appreciated on my end. Stay tuned as the diagnosis continues. I want to get this figured out as badly as you do.

David

 

I have had this exact issue: over 4k feels like the drive train is stuttering. No Codes, but after about two weeks the car started missing at idle with the stutter under load, still no codes. few weeks before experiencing the stutter, I replaced both fuel pumps, secondary had died. Current symptoms were nothing like the 3k flat line + crazy pinging under load.

Turned out my spark plugs were played, almost a .060 gap! after replacement runs like a champ up to 6k. the entire time i swore my diff was going to explode (it is slowly failing; likes to whine + minor output shaft bearing play).

Hope this helps + easy one to check.

 

Amazing. Thanks man. Our symptoms are almost identical. I'm going to get right on that and report back. Cheers!

 

Morning gents,

Okay, so I'm half way through the big day of changing the secondary fuel pump. I have the tank out of the back of the car and on the ground. Just wondering how to determine the primary pump from the secondary pump while looking inside the tank. Is it the one closest to or further away from the level sensor? I had the primary pump replaced last summer, this is why I'm not doing both simultaneously. Just trying to make sure that I swap the right one before I start hooking things back up.

Any suggestions would be appreciated

David

 

Disregard! Fished them out and replaced the one with the OE part number on it. Now to get this bugger of a tank back in. Stay tuned..

 

Always a fun task! I had the pin no's of the primary and secondary written down somewhere while I was doing the job, but I don't know if I still have it around. Sounds like you got it figured out though.

 

Well, I'm happy to report back and bring this thread to its conclusion! Got the secondary pump installed and although the low volume, high-pitch whine (likely from the aftermarket primary pump) remains, the power loss issue has been solved! No more cut-out after 3500RPM

Many thanks to those who contributed to this thread and helping me figure this one out, including but not limited to:

Highhorse
MarkSF
dsetter
JagV8
Mvirgil

Happy to have this one checked off the to-do list.

Thanks again, gents. Cheers!

 

Mine also whines with the denso unit I put in in to replace the primary. No other symptoms that would indicate a bad pump or something, after testing wiring I just banked off the subwoofer hole and no longer hear it in the cabin. Hoping that's the end of that...

 

Good to hear it's fixed!