1999 Blazer, 116k. Slow starts, odd idle at times, key on fuel pressure hits 55ish then drops to 46/47 quick, truck running pressure stays at 55/56, key off it quickly drops to 13/14 and stays there.
Recently replaced the leaking intake gaskets they are known for, tune up with AC Delco wires/plug/cap/rotor. Also replaced all of the vacuum lines i could with new as well.

I know the spider has an updated version, already have a pressure valve and the gaskets to pull the upper intake. But does this sound more like a pump, valve or the injectors themselves? I'm leaning to just the valve but it's a PITA to split the housing and find the injectors bad too...plus costly. Any thoughts or tips?

Thanks guys

 

check pressure at the inlet of the fuel filter. if it drops then its the check valve in the pump,if not id say its the injection system.

 

I agree ^^

If it fails either part of the fuel pressure and leakdown test, it only tells you there's a problem, it does not tell you what's causing the problem. At 55psi, your fuel pressure is too low, and leakdown is excessive. The next step is to modify the pressure tester so all pressure and fuel flow ends at the tester. Then connect it to the line at the fuel filter. Pump running, pressure must be 73psi to 108psi and must remain above 55psi for at least 10 minutes. If it fails to build proper pressure, check voltage & connections at the pump. If they're ok, the pump needs replacement. If leakdown is excessive, replace the pump. If both tests pass, we move on to checking the injectors and fuel pressure regulator.

 

Do they make an adapter for the fuel line at the pump to attach a hose to for the pressure tester or do i need to hack up a fuel filter? I've got access to alot of brass airline type fittings at work and with shops we work with.
Hope to get this truck sorted out this weekend. Been an on going 2 month project fixing a little at a time each time.

 

You can make an adapter with a 3/8" female quick connect coupler on one end, and a 1/4" male flare on the other. Plug the coupler onto the fuel filter, connect the standard fuel pressure tester to the flare. Or you can make one like this, which is more versatile, it connects inline at the fuel filter: