RAM 2500 Van V8-318 5.2L VIN T Magnum CNG SFI (1997)
4. Increase the engine speed to 2000 RPM and observe the vacuum gauge. The vacuum will decrease when the speed is increased rapidly, but should
stabilize at 16-21 inches Hg and remain constant. If the vacuum remains below 16 inches Hg, the exhaust system is restricted or blocked. Stop the
engine and proceed to the next step.
5. Disconnect the exhaust pipe at the manifold.
6. Start the engine and increase the speed to 2000 RPM. Observe the vacuum gauge.
7. If the vacuum stabilizes at 16-21 inches Hg, restriction or blockage is either in the exhaust pipe, catalytic converter, muffler or tail pipe.
8. If the vacuum stabilizes below 16 inches Hg with the exhaust pipe disconnected, the exhaust manifold is restricted.
9. Stop the engine, connect the exhaust pipe and remove the muffler. Start the engine and increase the engine speed to 2000 RPM. Observe the
vacuum gauge.
10. If the vacuum stabilizes below 16 inches Hg, the restriction is in the catalytic converter.
Note: In the event of a catalytic converter failure, always inspect the muffler and ensure converter debris has not entered the muffler.
11. If the vacuum is normal, the muffler or tail pipe is restricted.
12. Stop the engine.
13. Disconnect the tachometer and vacuum gauge.
