How is the fuel pressure set in a GM return system?
Fuel Pressure Explained. With a return system, the base pressure is set with the engine off, but the pump running. For a GM, this pressure is usually set to 58psi (factory fuel pressure in the rail). The vacuum/boost referenced regulator will help to change the pressure in the rail based on the pressure in the manifold.
How much psi do I need for the 4.3 injector?
Ive had a lot of experience with the 4.3 on previous vehicles I owned and they need at least 58 psi to start. Early versions of the injectors were prone with sticking poppets and leaking regulators. Hell, back in the day when my 94 Jimmy was still under warranty GM changed the injector 3 times.
When do I lose fuel pressure on my Silverado?
I have a 2005 Chevy Silverado 1500 and I lose pressure gradually when I shut off the engine. When I go back to start it within an hour I cant get it to fire unless its turned over several times and I hit the gas. Ive replaced the fuel pressure regulator and ICV. No codes whats so ever.
What should fuel pressure be in a truck?
Fuel pressure test when cold, turn key on and spikes to almost 60psi, then quickly drops to about 10psi, but truck still starts ok. Holds pressure around 52psi. Turn key off and pressure drops rapidly. When motor hot, turn key on and climbs slowly mid 50s, then falls back down. Long crank and need to pump pedal to catch.
What is the nominal pressure of a Ford fuel injector?
Ford Racing’s fuel injectors are always rated at 39.15psi delta, so the fuel injector sizing discussions found below will assume a fuel pressure of at least 39.15psi delta. There are some exceptions to the above-mentioned nominal injection pressure.
Fuel pressure test when cold, turn key on and spikes to almost 60psi, then quickly drops to about 10psi, but truck still starts ok. Holds pressure around 52psi. Turn key off and pressure drops rapidly. When motor hot, turn key on and climbs slowly mid 50s, then falls back down. Long crank and need to pump pedal to catch.
How to check fuel pressure in Gen 5.7L?
1. Fuel pressure regulator- pull the vacuum tubing off the fpr and if there is fuel, diaphragm is shot, Replace the fpr. Oh I did not notice you have an old gen 5.7L. FPR is inside the intake. Can’t check the diaphragm condition unless intake is off. 2.
How can I tell if my fuel pressure sensor is correct?
First, make sure that the fuel pressure sensor is correct. Check the fuel pressure with a manual fuel pressure gauge to figure out if you can find any problems with the pressure. If so check fuel pressure regulator.
What should I do if my fuel pressure is high?
Start the engine; the fuel pressure should remain the same. Snap the throttle and make sure it increases. This an indication of a good fuel pump. Test a vacuum operated fuel pressure regulator’s operation by removing the vacuum line while monitoring fuel pressure. The pressure should increase (5-15 psi.).
When does fuel pressure drop after turning off the engine?
Turn the engine off, but key on and pressure gradually drops all the way to 18 PSI over 20 minutes. Turn the key off then key on but no engine start, I can hear the 2 second fuel prime and the PSI shoots up to 55 PSI and engine still has to turn over for 3 or 4 seconds without gas pedal, 1 or 2 seconds with gas pedal.
What should fuel pressure be when ignition switch is on?
When the ignition switch is ON and the fuel pump is running, the fuel pressure indicated by the fuel pressure gauge should read 379-427 kPa ( 55-62 ps i). The spring pressure inside the fuel pressure regulator controls the fuel pressure.
What happens to fuel pressure when you turn the key off?
SOLVED: Fuel pressure bleeds off when i turn the key off . – Fixya Hooked a fuel pressure test up . the pressure pops up to 55 to 58 psi. i turn key off pressure drops down to 15 20 psi Clicking this will make more experts see the question and we will remind you when it gets answered.
What should the pressure be on the fuel system?
Check the video at the start of this section so that you have an idea how to do a maximum pressure test. If you need to replace the fuel pressure regulator—or whenever you need to disconnect any part of the fuel system—relieve fuel system pressure before beginning to work on the system. Fuel pressure on some models can reach up to 60 psi (414 kPa).
What should the base pressure be on a GM return system?
With a return system, the base pressure is set with the engine off, but the pump running. For a GM, this pressure is usually set to 58psi (factory fuel pressure in the rail). The vacuum/boost referenced regulator will help to change the pressure in the rail based on the pressure in the manifold.
What should the fuel gauge be without starting the engine?
Without starting the engine turn the ignition key to the on position the gauge should jump up to between 45 psi and 58 psi (DPI) direct port injection systems, throttle body injection (TBI) should be between 13 and 17 psi in most cases as the system primes.
Why does a returnless fuel pump lower fuel pressure?
This lowers the ultimate output of the injectors. Some returnless systems will actually vary the pump output to emulate a referenced system, or to offer more fuel pressure at higher demands and less fuel pressure at lower demands. Ford fuel systems modulate the pump in an effort to maintain effective fuel pressure at 3 bar.
What’s the best way to relieve fuel pressure?
With your hand, remove the vacuum hose from the top of the fuel pressure regulator. Connect a hand-operated vacuum pump to the top of the pressure regulator. Apply about 16-inches Hg of vacuum to the regulator to push the fuel in the lines back into the fuel tank.
How does a return style fuel injector system work?
Return style systems hold a big advantage in that with a vacuum/boost referenced fuel pressure regulator, the system can maintain a CONSTANT effective fuel pressure, which can extend the range of fuel injectors and help them function at lower fuel demands as well.
What can I do to relieve the pressure in the fuel tank?
Warning. Always loosen or remove the fuel filler cap on your vehicle when you are working on the fuel tank. That will relieve pressure build-up in the tank. Always disconnect the negative battery cable when working the fuel system of a car.
Where is the fuel pressure regulator on a car?
Disconnect the negative battery cable using a wrench. This will prevent sparks, which could ignite fuel and fuel vapors. Locate the fuel pressure regulator on the fuel rail. The rail is mounted along the top area of the engine. Make sure the regulator is vacuum operated.
What happens to fuel pressure when you shut off the engine?
That system, especially on fuel-injectede models, operates under high pressure and remains like that even when you shut off the engine. Different vehicle manufacturers have devised several methods of relieving fuel pressure.
Where is the fuel pump on a car?
Unplug the fuel pump electrical connector on the sending unit/pump assembly. Start the engine and let it idle until it stalls. Then turn off the ignition switch. Disconnect the negative battery cable. Locate the fuel pump fuse under the dashboard or in the engine compartment. It is usually located on the driver’s side of the vehicle.
How is fuel delivery timing in a computer?
Fuel delivery timing for starting is also in the map in the computer. Ignition is by static induction spark with dwell control in the power module and spark advance curves programmed in the computer. ELEMENTS MAKING UP THE SYSTEM Fuel circuit
How can I test my fuel pressure regulator?
So, testing the fuel pressure regulator, is a simple task that requires some minor equipment; and a short amount of time. Firstly, spend the money and get a good, fuel pressure testing gauge. I have heard of people using a Tire Gauge, BUT Don’t, DANGER.
How is ignition timing related to air fuel ratio?
Control of the air-fuel ratio and the ignition timing is the basic element in optimizing engine performance. The air-fuel ratio is given by the ratio, in terms of weight, of air and gasoline drawn in by the engine. The ideal or stoichiometric ratio is that which produces total combustion.
Fuel Pressure Explained. With a return system, the base pressure is set with the engine off, but the pump running. For a GM, this pressure is usually set to 58psi (factory fuel pressure in the rail). The vacuum/boost referenced regulator will help to change the pressure in the rail based on the pressure in the manifold.
When to replace a bad fuel pressure regulator?
With the hose removed, fuel pressure should increase by 8 to 10 PSI. Its also a good idea to check for fuel inside the regulator vacuum hose, which would indicate a leaking diaphragm. If the fuel pressure regulator is found to be bad, it should be replaced.
What’s the fuel pressure on a pulse fuel pump?
The pulse fuel pump operates through alternating crankcase pressure to deliver fuel through the water-separating filter to the vapor separator. •Fuel pressure @ Idle – 2-3 psi (Minimum – 1 psi). • Fuel Pressure @ Wide-Open-Throttle – 6-8 psi (Minimum – 4 psi).
Where is the regulator on a fuel pump?
As the name indicates, this type of system has no return line to the fuel tank and no externally mounted regulator. Instead, fuel pressure is controlled in tank. The fuel pressure regulator is usually built into the fuel pump assembly. This design allows for more precise fuel control and reduced emissions.
How can I check the pressure on my fuel pump?
Attach the fuel pressure gauge at the fuel rail test port. Cycle the key on and off a few times and watch the pressure should go up to specifications and not drop for a long time or more than ten minutes before any drop of more than 1 or 2 psi is seen.
Where does the fuel pressure sensor go on a rail?
When you stick a fuel pressure sensor on the end of a rail, it is reading the pressure inside of the rail. While this number is important, it is only half of the story.
What’s the difference between base and effective fuel pressure?
The reference to the regulator will allow it to adjust and lower the pressure in the rail to 48psi, resulting in 58psi effective pressure, which is the same as the base pressure. When the engine is making 10psi boost, the regulator will adjust and increase rail pressure to 68psi, again resulting in 58psi…
What should fuel pressure be when engine is off?
Observe the fuel pressure gauge while the engine runs and after shutting off the engine. Fuel pressure should hold to specs, while the engine is running, and after turning off the engine. With the engine off, pressure should hold for about 5 minutes. If necessary, consult your repair manual.
This lowers the ultimate output of the injectors. Some returnless systems will actually vary the pump output to emulate a referenced system, or to offer more fuel pressure at higher demands and less fuel pressure at lower demands. Ford fuel systems modulate the pump in an effort to maintain effective fuel pressure at 3 bar.
Can a failed fuel pump cause a failed pressure regulator?
[&hesitation&]. However, other worn out or failed components—like the [&fuel&] filter, fuel pump, and automatic transmission issues—can also [&cause&] similar symptoms to those of a [&failed&] [&pressure&] [®ulator&]. So you need a way to troubleshoot the [®ulator&] in your vehicle whenever you suspect a malfunction.