"Making Turbocharger Technology Work"
Fuel Pressure Regulator Installation Instructions
Purpose of the Rising
Types of Regulators
2.) The regulators can be mounted in any position. For convenience, place the adjustment screws within easy access. The most difficult aspect of installation is getting the fuel lines onto the correct fittings.
3.) Older model regulators made from castings (20002-20007), had labels of IN/OUT on the barb bosses. IN is for the fuel line from the stock regulator. OUT is the return line heading back to the fuel tank. The IN and OUT of the new regulators (2022-2027) are slightly different, as there is only an "IN" label. The blank port is the "OUT" port.
4.) Fuel fittings for the 2022, 2023, & 2025 are 1/8 NPT. The 2027 has 1/4 NPT threads. Some form of thread sealant is advised. We prefer one drop of Loctite per joint. In general, please avoid teflon tape as the residue and debris can get into the fuel system if not extremely careful. The threaded bosses on the regulators are strong enough for a zillion ft-lbs of torque, they will not crack. They can be stripped, but neither failure is warrantable.
Only one adjustment is required of the NA and OEM turbo/supercharger regulators, whereas the aftermarket turbo requires two adjustments. For the NA/OEM regulators, only the maximum pressure achieved is of interest. For the aftermarket, both the point of onset and the maximum pressure are adjusted.
In all installations, we urge tuning be aided with an air/fuel ratio meter and fuel pressure gauge.
NA Regulator, 2023
An approximate graph of fuel pressure is shown in figure 2023. This is an approximation only for the purposes of suggesting to you the general ranges of operation.
OEM System Regulator, 2022
Regulator, 2025 & 2027
Pressure calculation: the
fuel pressure required increases with the square of the boost
Needed fuel pressure = (PR2 x Base Fuel Pressure) + Boost = (1.412 x 36) + 6 = 77.5 psi
The first adjustment is of fuel pressure is at the atmospheric pressure point, and can best be done at idle. To simulate passing through the zero point, the vacuum line must be removed from the regulator. The regulator then sees atmospheric pressure as a signal, same as zero on the boost gauge. Control of the fuel pressure at the zero point is by the Allen screw in the center of the regulator. Clockwise on the screw will raise the pressure. Once adjusted, plug the vacuum line back onto the regulator and observe the fuel pressure drop to the stock figure. A suggested pressure for starters is 48 to 50 psi. Please understand, this will vary from engine to engine, and is not a magic number. The magic number is whatever pressure your vehicle requires to pass thru the boost onset without the lean flat spot. It is not unusual to see pressure anywhere from 40 psi to 55 psi. Use whatever works best.
The second adjustment, the needle valve, controls the rate of gain of fuel pressure versus boost pressure. The lowest rate of gain is with the needle valve fully open, the highest, fully closed. Clockwise closes the needle valve. Figure 2025 offers a typical guide to fuel pressure versus boost pressure.
Caution: There is a vague limit that exists with regard to the maximum possible fuel pressure. The industry "rule of thumb" of injectors jamming at 50 psi and the flow not increasing with pressure is not correct. It is possible for a very large injector (90 + lbs/hr) to jam at 100+ psi of fuel pressure. At anything less than that, jamming is not going to happen.
Checking Pump Pressures
The maximum fuel pressure is controlled by the needle valve and must be determined while driving the car under boost. Start with the needle valve closed, which is fully clockwise. It is unlikely the regulator will need this adjustment, but the test also serves the purpose of proving the pump will do the job needed. A weak fuel pump will cause a drop in fuel pressure as the engine is revved higher. If the pump cannot maintain the desired psi to the engine redline, it is not in satisfactory condition to feed the turbo/sc engine and must either be replaced or supplemented with an auxiliary pump.
1. Jams at maximum fuel
2. Pressure doesnt
3. Pressure rises, but not
4. Pressure rises, but too high:
5. Fuel pressure oscillates:
6. Regulator buzzes under boost:
Warranty: The regulators are warranted for workmanship and function for one year from the date of shipment from our facility. No open threads, user installed threaded items, or adjustable threads are warranted in any way. If problems arise from using teflon tape, Cartech reserves the right to refuse warranty coverage for damages caused to the regulator.
As always, if none of the above is effective in tuning your regulator, give us a call at the number below. If needed, return the regulator to us for service.
Copyright ©2002 Bell
Experimental Group, Inc.
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