I have a 2000 Chevy blazer 5 speed, I started having problems with the fuel gauge flaking out on me, and then eventually started having hard start issues. I hooked my fuel pressure gauge and wasn't happy with the readings. So i replaced it with the extra AcDelco pump I had downstairs. The truck still hard starts and is progressively getting a little worse. Now I have a real rough idle and at every stop light, the truck shakes a little bit and what not but the Tach stays steady at 600 rpms, also no CEL. When I let the clutch out after sitting at a red light, Its does a little stutter almost like it flooded itself. But after the half second of studdering it drives like a dream. any ideas what this could be?

 

after you replaced the pump, did you check the fuel pressure again? What was it before when you were not happy with it?

 

Old pump key on engine off was 51 psi, the leak down was more than 15 or 20 psi after 10 minutes iirc. Did not check current pump will do first thing tomorrow.

 

OK I tested the new pumps fuel pressure today. With key on engine off, I couldn't even get a reading because by the time i walked to fuel pressure gauge it was already down to 40-45 psi, the fuel pressure would rapidly drop to 0 within 30 seconds. engine on was 51 psi. not sure if thats a little low because of what ever problem exists

 

Time to isolate the fuel pump from the regulator to determine which is at fault. Usually new pumps are good...but not always! Only way to know is to isolate the fuel pump and check pump pressure.

Capt has outlined parts needed in several threads....just do a search to find them.

Probably the fuel injector spider or pressure regulator is leaking inside the plenum. Easier to replace than the fuel pump.

 

Remove your upper intake plenum (Just the black plastic part, this exposes all of the possible leak points) then reconnect the fuel lines and pressurize the fuel system again but DO NOT START. Most common issue with this leakdown problem is the diaphragm in the fuel pressure regulator has ruptured and its dumping raw fuel into the intake, #2 is the checkvalve in the pump. You changed the fuel pump and your bleed down problem still exists so that points at the regulator, of course it could be the new pump but chances are better that the pressure regulator is the culprit, if you dont find an active leak in the intake THEN you will need to isolate the pump to figure out where the pressure is bleeding to.
If i was working on this i would get a regulator before i even started removing the plenum.

 

thanks for the responses! I actually just got done removing the plenum. I saw on the back side of the manifold that the carbon was all washed away directly under the regulator. all of the lines looks fine. replaced the regulator and got the plenum back on. the only thing in my way at the moment is getting those two fuel line hooked back up. ive been wrestling with them for an hour now. Does anyone have any tricks for doing this?

 

I put some oil on them and also undo the bracket at the back so the lines can move around more.

 

I have a 98 jimmy and had the same problem and it was my fuel injector spider.