Fuel system issues
 

Hello all: I'm having some issues with starting my 2001 blazer (4.3, 4x4 4 door). It has been problematic for the last two months or so, taking 10 seconds or so of cranking to get it started. Yesterday (it was 101 here) it was also stalling and I thought it was maybe vapor locking. I tested the fuel pressure and it was priming and holding pressure to spec while the engine was on but as soon as you turn the engine off I would lose all my pressure in about 15 seconds. It hasn't misfired at all and hasn't thrown any codes. I've narrowed it down to check valve, fuel pressure regulator or injectors…but I don't want to have to open the upper intake manifold or drop the tank and have it end up being something else. Anyone have any ideas on how I could narrow it down a bit or have experience with this?

i would think the checkvalve at the fuel pump would hold pressure for longer than that . how are you measuring the fuel pressure? do you have a gauge on the fuel rail? they can be purchased for 50 or less....that would help you figure out what's going on...i installed one on my son's v-6 mitsubishi and it's been very interesting.....pressure stays at 40 for like an hour after it's shut off....

There is a test jig to use at the fuel filter junction to test the FP check valve.. do a search for fuel pressure test procedure

https://blazerforum.com/forum/tech-a...agnosis-23038/

Test pressure at the fuel filter as the tech article that pettyfog linked to describes. Details of how to do this through fittings/etc are included in there as well.

If the pressure drop still occurs with the fuel system disconnected or shut off at that location, then the problem has to be with the pump itself.