Nope, you didn't read the thread We need to know what the fuel pump max output pressure and leakdown are, and, engine running pressures are worthless information, it means absolutely nothing on this system.

 

Both of which are listed unless I am misunderstanding the the thread I'm not going to pull the filter again and get adapters and such to test there since leak down at the Schrader valve is less than 1 psi. I know it says running doesn't matter but gm lists operating fuel pressures because I have seen them posted before in a vacuum leak thread. Weird spot but makes sense as the FPR is manifold vacuum dependent. That's why I have listed all 4

Unless I misunderstand your thread since there is basically no leak down the filter removal isn't even needed. The wide range of acceptable unregulated pressures makes me think that my pump would most likely be able to prime to the very low end of that spectrum or just under. Uless your the belief Is the pressure read is all the pump is capable of unregulated i.e. 58psi at the Schrader will be 58 psi unregulated at the pump as well?

My thoughts with the pressure regulator are that if it had failed there would be leakdown is it possible for it to fail too tight as in not allowing enough pressure. I just hadn't seen anyone mention that before so it never entered my thought process. Just need a little clarification before I get covered in fuel again.

 

It explains in the thread.... when you check pressure at the service port, the reading is either regulated fuel pressure, or fuel pump max output pressure, which ever is lower. Your KOEO, pump running pressure at 58psi is low, but if that's all the pump can build, and your regulator is set above 58psi, you don't know what regulated pressure is, and you have a serious problem brewing with the pump, and you won't know it, until you check it. We need to know pressure and leakdown at the service port and at the fuel filter outlet to diagnose the system. The option is start guessing, your choice.


The older CMFI systems used a "rule of thumb" pressure drop while running. It is merely a guideline, not "Gospel". The CSFI in your 2002 is a completely different animal, and the "rule of thumb" does not apply. All pressure readings are taken with the fuel pump running, engine off.

 

Yeah that's what I figured you were after I was editing my post above when you replied. I have to pull the pump already due to the sending unit failure. It seems that the sending unit is ~$90 and a complete pump is ~$150. Either way I have to drop the tank so I'm seeing it as a $60 insurance policy right now. I don't know if this truck is using the poppet style injectors or the updated one as I don't have the service records. I do know everything on this truck is ac delco and it's all replaced parts. So far. I know that doesn't make much of a difference to the troubleshooting right now but I also have a complete injection spider with FPR here from a 2004 blazer in case the regulator is bad. So really I'm just going to be out more time if the pump is fine and I yank it. I personally feel more confident driving it with a new pump amy way since 115 degree summers are near

 

$150 for an AC Delco fuel pump module is a fantastic bargain! Better make sure it's genuine, and not some cheapo China knockoff. You've probably seen other threads on the forum about fuel pumps in these things, use AC Delco or Delphi only.

 

Mu1733 ac delco from rockauto is 150 shipped no tax 155 from amazon with tax add. amazon also has the delco for 168 with a $15 instant rebate. It's pretty standard non dealer price now.

 

If your doing the sender too its MU13 #25163489 and its $225.79 (1Left) Providing its a 4 door.

 

Yes 4dr. I'm not seeing that part number anywhere. This is the description on the mu1733 ACDelco MU1733 GM Original Equipment Fuel Pump and Level Sensor Module with Seal, Float, and Harness. I called the local dealer they told me that includes the sending unit and is the correct part for my vin. But I never trust a parts counter.

 

I was on RockAuto.com and that is the number listed there. I know the MU13 is the older number I believe there is an MU1735 . I believe the VIN would give the most accurate. Just make sure it includes the sending unit as the listing in RockAuto does not, at least the way Im reading it.



Ignore my post I was looking at it for an earlier model. Sorry. Message still stands the same make sure it includes the sending unit.

 

Saw the update pretty sure without looking it up the mu1735 is for a k53 rpo vehicle. The robust fuel system. I don't have that rpo I don't even understand what that rpo gave you other than a more expensive fuel pump