These were the early “1st Gen” years in the Dodge pickups, with a rotary style VE injection pump and the first of the “12-Valve” 5.9L engines. They did not have intercoolers and most apparently did not have factory tachometers or crankshaft position sensors. Their fuel was supplied with an engine-mounted mechanical “lift pump” at low pressures (3-7 psi typically). The VE injection pump is completely mechanical, with no electronic parts or tuning. These engines generally need a full snubber kit for the fuel pressure gauge’s sensor.
These years (late “1st Gen”) continued with the rotary VE pump but added an intercooler and a crankshaft position sensor which is used for the charging system voltage regulator but also feeds a harness for the optional tachometer, which is typically taped to the steering column under the dash. These engines generally need a full snubber kit for the fuel pressure gauge’s sensor.
These are the “Early 2nd Gen” years, with a new truck body style and a change to a piston-type P7100 injection pump (commonly known as a “P-Pump”) which increased power. They continued to use a block-mounted mechanical lift pump but at higher pressures (15-20 psi typically, but some aftermarket kits pushed that to 50+ psi). A common retrofit to 1st Gen trucks is to convert to P-Pump fuel systems. The P7100 injection pump is completely mechanical, with no electronic parts. These engines generally need a full snubber kit for the fuel pressure gauge’s sensor.
The “Late 2nd Gen” years brought a new version of the 5.9L Cummins: the 24-valve head (4 valves per cylinder) and the VP44 electronic injection pump. The VP44 is capable of drawing fuel from the tank without a lift pump, BUT it requires the constant flow of fuel (provided by a lift pump) to keep it cool. In other words, if the lift pump fails (identifiable by a drop in fuel pressure) the VP44 will overheat and fail (very expensive replacement). Due to these failures, this vintage is the most critical application of fuel pressure gauges (as well as a market for buying gauges). These engines generally need a full snubber kit for the fuel pressure gauge’s sensor.
These are the “Common Rail” years of the 5.9L Cummins. They used a Bosch CP3 pump to raise fuel to extremely high pressures (up to 26,000 psi) as commanded by the engine controller. These years use the Rxx288 Rail Pressure gauge. Generally the CR engines do NOT have fuel pressure pulsations like on the earlier engines, and at most they need a simple R7800 snubber (but most do not need anything).
These are the 6.7L Cummins engines, which uses a higher pressure (29000 psi) CP3 pump, and uses the Rxx289 Rail Pressure gauge.
These use a different connector for the Rail Pressure sensor, requiring the Rxx289C gauges.