w317chester
Seaman
- Joined
- Jul 7, 2010
- Messages
- 54
Ive been having an issue with my 1996 black scorpion 5.7L MPI engine. The engine cranks and idles fine but whenever I give it some throttle is hesitates or cuts out before accelerating. Its also backfiring (I believe through the intake manifold) when I give it throttle.
Here a list of stuff I have already done/checked:
1. Just had heads completely rebuilt
2. Almost all new engine gaskets
3. Installed new thermostat
4. New oem recommended Spark plugs with correct gapping
5. New plug wires
6. I have plugged in a codemate code reader and it doesnt give any error codes
7. Last thing I did was check fuel pressure on fuel rail and it was about 22psi at idle (supposed to be around 30psi). So I disconnected vacuum line going to fuel pressure regulator to check vacuum coming from intake manifold and it was about 13in. mg (seems about right?). With handheld vacuum pump I then applied 10in.mg vacuum to fuel pressure regulator and pressure drop was about 5 psi (about what its supposed to be), so fpr seems to be working fine.
8. The next thing I knew to do was disconnect hose from fuel tank and place it in a different fuel source. However pressure did not change.
Could it be fuel pump?
So this is where Im at and I am completely stumped.
Any help/suggestions would be greatly appreciated as I have limited experience.
Here a list of stuff I have already done/checked:
1. Just had heads completely rebuilt
2. Almost all new engine gaskets
3. Installed new thermostat
4. New oem recommended Spark plugs with correct gapping
5. New plug wires
6. I have plugged in a codemate code reader and it doesnt give any error codes
7. Last thing I did was check fuel pressure on fuel rail and it was about 22psi at idle (supposed to be around 30psi). So I disconnected vacuum line going to fuel pressure regulator to check vacuum coming from intake manifold and it was about 13in. mg (seems about right?). With handheld vacuum pump I then applied 10in.mg vacuum to fuel pressure regulator and pressure drop was about 5 psi (about what its supposed to be), so fpr seems to be working fine.
8. The next thing I knew to do was disconnect hose from fuel tank and place it in a different fuel source. However pressure did not change.
Could it be fuel pump?
So this is where Im at and I am completely stumped.
Any help/suggestions would be greatly appreciated as I have limited experience.
