95 blazer cpi vin w

sorry for the long post lol.


alright. so I just wanted to have a look under the plenum and found a few leaks. regulator was leaking and the nut kit had a small crack in the line. so I replaced all that. started it up and it was missing a bit. at a stop light it would bog way down when giving it gas then clear up. so I thought I got a bad regulator. went to advance auto and returned it and got another.


put the 2nd new one in and it made it even worse. it wouldn't even idle hardly at all let alone drive down the road. checked the o2 sensors and they were reading straight lean. so I shot some brake cleaner in it and bam idled smooth just until it burned off the extra fuel. checked fuel pressure 50psi key on about 45psi running. so I thought maybe fuel pump.


replaced fuel pump. also replaced that dampener thing with rubber hose and hose clamps. still same thing. 45psi running and when off key on the pressure drops to almost 0 in a minute or so.


so I popped the plenum once again and adjusted the regulator to 62 psi key on. running 55psi now it will start up and run like a champ. perfect. but the pressure drops to about maby 10 psi in under 2 minutes. but starts up every time without a hiccup. no hesitation no stumbling no missing. just starts and runs smooth even after I shut it off let pressure bleed off then quick restart after a few minutes.




before I did anything, the truck was running great before. just wanted to see what was under there. well maby a miss here and there. and I checked fuel pressure awhile back and it was 55psi running I think but it was in spec I do remember. and also it didn't bleed off as fast as it does now. I think it was something like 2psi a minute or so. it bleed off pretty quick but never like this.



also every time I popped the plenum it was high and dry in there.


so did I get a ANOTHER bad regulator or what?

 

There are no "engine running" fuel pressure specs, all tests are done with the engine off.

Key on, engine off, fuel pump running, (regulated fuel pressure) on your 95 needs to be 55psi to 61psi. Pressure must remain above 50psi for at least 10 minutes after the pump shuts off. If leakdown fails, which yours does, pressure and leakdown must be checked at the fuel filter outlet. All pressure and flow must end at the pressure tester. Here is a list of parts necessary to build the adapter: 1996andolderFuelFilterAdapterforCheckingFuelPump_z ps548e63d0.jpg Photo by cwhook | Photobucket

Pressures while testing at the filter are: 70psi to 100psi, and must remain above 50psi for at least 10 minutes after the pump shuts off.

Post both sets of pressure readings, (4 different numbers). The results will tell where the problem is and more diagnosis will be necessary to pinpoint the problem.