No test port on fuel rails

define power.
1: can't hear buzz?
2: fuel pressure at the fuel rail is zero PSI cranked.
3: my volt meter tells me the pump has 0vdc across the pump pins cranked?

I cant guess any of this and is 100 %^ Germain.

You should have a test port on the Fuel Supply rail, use a tool from a local auto parts "Tool Loaner program" where you can borrow tools for free,w/a deposit of course,then follow the steps provided;

MPI Fuel System Pressure Test

The MPI fuel system used in vehicles equipped with a 4.OL engine employs a vacuum balanced pressure regulator. Fuel pressure should be approximately 55-69 kPa (8-10 psi) lower with the vacuum line attached to the regulator than with the vacuum line disconnected. System fuel should be 214 kPa (31 psi) with the vacuum line connected to the regulator and 269 kPa (39 psi) with the vacuum line disconnected. CAUTION: Some fuel may be discharged when connecting fuel gauge to fuel rail.

1. Connect a 0-414 kPa (0-60 psi) fuel pressure gauge to test port pressure fitting on fuel rail (Fig. 7).
2. Remove vacuum line from pressure regulator.
3. Start the vehicle.
4. Note gauge reading. With vacuum line disconnected, fuel pressure should be approximately 269 kPa (39 psi).
5. Connect vacuum line to pressure regulator. Note gauge reading. Fuel pressure should be approximately 214 kPa (31 psi).
6. If fuel pressure is not approximately 55-69 kPa (8-10 psi) higher with vacuum line removed from regulator, inspect pressure regulator vacuum line for leaks, kinks or blockage. CAUTION: Fuel pressure will rise to as much as 655 kPa (95 psi) when the fuel return tine is pinched shut, shut engine down immediately after pinching oft fuel return line.
7. If fuel pressure is low, momentarily pinch shut the hose section of the fuel return line. If fuel pressure remains low, inspect the fuel supply line, fuel filter, and fuel rail inlet for blockage. If fuel pressure rises replace fuel pressure regulator.
8. If fuel pressure is above specifications, inspect the fuel return line for kinks and blockage.

Capacity Test

1. Remove the cap from the pressure test port in the fuel rail.
2. Connect a 0-414 kPa (0-60 psi) fuel pressure gauge to the pressure fitting on the fuel rail (Fig. 7).
3. Start the vehicle. Pressure should be approxi- mately 214 kPa (31 psi) with the vacuum hose connected to the pressure regulator and 269 kPa (39 psi) with the vacuum hose removed from the pressure regulator.
4. If the pressure is not to specification, check the following before replacing the fuel pressure regulator:

• 4a - Inspect the fuel supply and return lines/hoses for kinks or restricting bends
• 4b - Check the fuel pump flow rate. A good fuel pump will deliver at least 1 liter of fuel per minute with the fuel return line pinched off. If the fuel pump does not pump adequately, then inspect the fuel system for a plugged fuel filter or fuel pump inlet filter (sock). Fuel pump flow rate can be done by connecting one end of an old A/C gauge hose to the fuel test port on the fuel rail and inserting the other end of the hose into a container of at least 1 liter capacity. Run the fuel pump by installing a jumper wire into diagnostic connector terminals D1-5 and D1-6. Be sure to pinch off the fuel return line or most of the fuel will be returned to the fuel tank.

Do a fuel pressure leak down test, the test port is located on the fuel rail that supplies fuel to the injectors on the top of the engine, the pressure should not drop more than 5 PSI after the engine is shut down, make sure the fuel gauge (special tool) is not leaking at the schrader port connection. If the fuel pressure leaks down right away you need to replace the fuel pump inside the fuel tank, it has a defective pressure check valve. I understand you can buy a universal test gauge from most parts stores for about $20.00 that hooks up to the above mentioned test port.

Hi Cassandra:
Check this procedure to removal and installing Fuel Pressure Regulator...

Fig. 1: TBI fuel pressure regulator

1. Remove the throttle body assembly from the vehicle as outlined in this section.
   

WARNING To prevent spring pressure release, hold the regulator housing against the throttle body while removing the mounting screws.

1. Remove the three retaining screws that hold the pressure regulator to the fuel body.
   
2. Disassemble the pressure regulator assembly. Note the location of the components for reassembly. Discard the gasket.
   

To install:

1. Install a new gasket and the regulator assembly. Tighten the three retaining screws.
   
2. Install the throttle body assembly as outlined in this section.

WARNING The pressure regulator diaphragm MUST be installed with the vent hole aligned with the vent holes in the throttle body and regulator housing!
Hope this helps; also keep in mind that your feedback is important and I'll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using Fixya, and have a nice day.

Hi.

If fuel pressure is low and you have already replaced the fuel pump, then the problem is usually the fuel pressure regulator. The pressure regulator is in same assembly with fuel filter. The assembly is located to the fuel tank, bolted to the truck's frame. The pressure is tested connecting a gauge like this : Set Sealey VSE952 to the port on the fuel rail. The pressure on Grand Cherokee must be around 49 psi plus or minus 5 psi. If engine runs but pressure is below 44.2 psi , check for a blockage in fuel supply line between fuel rail and fuel pump module (e.g.kinked line). If the line is not blocked, replace fuel pressure regulator and filter. Test pressure with and without fuel cap on.

Another test to be done is reading pressure, then shutting the engine off with the gauge connected. If pressure goes down too quick, then the regulator is defective. After 5 minutes the pressure should not go below 24 psi. If it does replace the regulator.

If regulator is OK check for leaks at the injectors that can cause fuel pressure drops.To check for injectors leakage clamp off the rubber hose of the pressure gauge tool between fuel rail and the port. If pressure staysr above 24 psi and before was dropping, then a fuel injector or the fuel rail is leaking.

Below a diagram representing the fuel rail and test port. The engines from same years like your six cylinder have the port and rail in the same position.






Regards.

Ginko

your primary is in the tank connected to the fuel pump(but usually doesnt need change unless something goes wrong and u need to change your pump.)your 2ndary filter is on the frame rail on the drivers side, just above the rear tire. Two hose clamps and a 11mm bolt on the fuel filter strap.Remember to relieve the fuel pressure from the tank and test port on the fuel rail that connects the the injectors.

CHECK FUEL REGULATOR ON FUEL INJECTOR RAIL,&ALSO FUEL PUMP, CHARLIE

Try this: turn key on for 5 seconds,but dont start. turn it off and turn it on again for 5 seconds then try to start it. If it starts up better, you need to test the fuel pressure.
hook up a test gauge to the test port on the fuel rail, try to start and watch fuel pressure, after it builds.to its max turn engine off, it should then hold pressure for a few or more minutes. if it doesnt there are three things that can let it bleed down.

There is a check valve built into the fuel pump that could be stuck open,
An injector could be leaking,
Or the pressure regulator could be leaking.
If it still has problem check your spark plugs to see if they are worn out with too much gap.

fuel pressure seems a bit high...could be a bad regulator. can't remember if yours is on top of the sending unit (on tank) or on the fuel rail though. Do more testing there.

does it have fuel pressure? the test port is on the top of the engine in the fuel supply rail to the fuel injectors.