The low pressure side of the fuel system is ok, we have fuel to the filter and I would assume to the fuel rail as well. We decided to install a pressure guage on the high pressure oil line from the pump to the valve cover and when turning over the engine we see no pressure at all therefore no fuel pressure to the injectors. We thought maybe cam position sensor but we are not receiving any engine codes while turning the engine over. Is the high pressure oil pump knowing for quitting on these engines?
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Re: 7.3 liter will not start.
Yes they are you stated that you have mech oil pressure did you install a gauge?. this is a fuel line pressure sensor on the right bank at the frt of the head this sensor is rail pressure that high pressure oil pump creates check you pressure there that will elimnate that head the other side is a little more of a pain to test. one other thing to keep in mind is that the cranking speed is very important, and have you checked the oil level on a 7.3 deisel if you are more than 3 qaurts low on oil you will trap air in the high pressure pump. this will cause a hard start our even a no start
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Since you mention "gas rail" I'm assuming fuel injected.
I'd check the fuel pressure in the rail. Should be around 40 PSI.
If pressure is OK then injectors not working. Time to check cps.
You know the spark side is OK since it will run.
First check there is battery voltage to the pump and the pump starts when the ignition is switched on , if not check fuse and relay, check wiring from relay to pump. If ok and the pump is working , check for fuel blockage from the tank inlet to the pump , some have a sock type filter in the tank pick up tube, if all ok remove the fuel filter , switch on and fuel should flow at the filter, fit a new filter, if still no fuel at the rail fit a fuel pressure gauge an check for low pressure , if ok, the fuel pressure regulator may be stuck causing a air lock replace it.
The fact that it will start with the throttle body cleaner means that the PCM is attempting to start the engine. The fact that there is fuel at the rail and there is pressure may be misleading. There may not be ENOUGH pressure at the rail to do the job. Check the fuel pressure regulator....pull the vacuum line off the regulator. If there is any fuel in the line, the regulator is faulty and must be replaced. This is the most likely candidate.
thats a first gen fuel injection system throttle plate and two soliniods fuel pump pressure 16-22 psi no tap to check so have to install tee and tap with gage if you have problems starting check out the two sensors on passanger side next to the plate( tps )
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.
Connect a 0-414 kPa (0-60 psi) fuel pressure gauge to test port pressure fitting on fuel rail (Fig. 7).
Remove vacuum line from pressure regulator.
Start the vehicle.
Note gauge reading. With vacuum line disconnected, fuel pressure should be approximately 269 kPa (39 psi).
Connect vacuum line to pressure regulator. Note gauge reading. Fuel pressure should be approximately 214 kPa (31 psi).
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.
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.
If fuel pressure is above specifications, inspect the fuel return line for kinks and blockage.
Remove the cap from the pressure test port in the fuel rail.
Connect a 0-414 kPa (0-60 psi) fuel pressure gauge to the pressure fitting on the fuel rail (Fig. 7).
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.
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.
U 1st need to test fuel pressure at the fuel pressure test port on the top of the engione in the fuel supply rail to the injector tops, it looks like a metal tire vale stem, u will need to buy a special fuel pressure tester to do this test. U should have around 55-60 PSI at idle, it should go up when u gun the engine but never go down, if it goes down the fuel filter or pump are suspect.