NEED HELP Fuel pressure low
- Thread starter Acw1247
- Start date
How does the vehicle perform after the engine starts and runs? If the vehicle runs nominally and can produce power throughout the entire gear ranges, what was the reason to Investigate this as a Problem? How are you determining your Fuel Pressure... since there are no Digital or Analog Gauges on your Dashboard to view these pressure parameters? If the Fuel Pressure Regulator is the Culprit... the last of the three attached Videos shows how to perform this R&R.
Do you mean that you have attached an actual Fuel Pressure Gauge to the Schrader Valve right near the Fuel Filter to view these conditions in real Time? By the way... unless the Fuel Filter has been changed within the last 50,000 Miles since 2003... then that R&R is long overdue and remains a possible culprit in lowering Fuel Pressure at the Fuel Rail and EFIs. This is how these three tasks gets done:
Fuel Pressure Test:
Fuel Filter R&R:
Fuel Pressure Regulator R&R:
Do you mean that you have attached an actual Fuel Pressure Gauge to the Schrader Valve right near the Fuel Filter to view these conditions in real Time? By the way... unless the Fuel Filter has been changed within the last 50,000 Miles since 2003... then that R&R is long overdue and remains a possible culprit in lowering Fuel Pressure at the Fuel Rail and EFIs. This is how these three tasks gets done:
Fuel Pressure Test:
Fuel Filter R&R:
Fuel Pressure Regulator R&R:
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It starts very rough then perks right up I changed the fuel filter 2xxx miles ago and I'm following the proper test procedures I've seen every video you posted but none of them show my exact issue im having a rough start with 30 PSI of pressure for a second then it goes away almost instantly then if I get it to start it's fine and has no problems perfect fuel pressure I'm testing it with a fuel pressure gauge from the shrader valve by the fuel filter
A Rough and Choppy Start condition could have a number causes that are NOT related to Fuel Pressure ...such as the CPAS (Cam Shaft Actuator Solenoid)for starters. Please raise the hood on your vehicle and examine whether or not the CPAS located on the Upper, Front Passenger Side of the Engine Head looks like it has Motor Oil contaminating the Electrical Connector. This device regulates the flow of Engine Motor Oil under pressure into and out of the Cam Phaser.
If the CPAS has the aforesaid Oil in the Connector problem...or its Internal Screens are clogged... it can make for an Idle that frequently stumbles since the Cam Phaser is designed in part to replace the actions at idle that are normally handled by a Fixed and Mounted EGR Valve. Also... with a clogged or inoperative CPAS.... the Engine will stumble at highway speeds as well. Once you have the chance to eyeball this situation... please let us know what you find.
Besides "Dirty and Worn Spark Plugs" issues that can also play a role here... Leaking Fuel Injectors can also put enough liquid gasoline down inside of each cylinder as to cause a Very Rich Fuel/Air Mix on Start Up as well. Post Message #11 in this link will also give you the Low Down on what all of the other Sensors in the System do in order to get the Engine Running Properly:
https://gmtnation.com/forums/threads/need-help-truck-wont-start.18882/#post-564181
By the way... FWIW ... As much as I try to "read the minds" of others that are in trouble... sadly I do not possess that "Amazing Kreskin" lobe in my Brain. So if you want better and more precise assistance... adding in exactly what you have done in the manner of testing or parts replacement, etc... as a preface to what you want to know will go a long way in cutting down how much time it takes to wade through any "Questions and Answers" before being able to get down to the very heart of the matter.
If the CPAS has the aforesaid Oil in the Connector problem...or its Internal Screens are clogged... it can make for an Idle that frequently stumbles since the Cam Phaser is designed in part to replace the actions at idle that are normally handled by a Fixed and Mounted EGR Valve. Also... with a clogged or inoperative CPAS.... the Engine will stumble at highway speeds as well. Once you have the chance to eyeball this situation... please let us know what you find.
Besides "Dirty and Worn Spark Plugs" issues that can also play a role here... Leaking Fuel Injectors can also put enough liquid gasoline down inside of each cylinder as to cause a Very Rich Fuel/Air Mix on Start Up as well. Post Message #11 in this link will also give you the Low Down on what all of the other Sensors in the System do in order to get the Engine Running Properly:
https://gmtnation.com/forums/threads/need-help-truck-wont-start.18882/#post-564181
By the way... FWIW ... As much as I try to "read the minds" of others that are in trouble... sadly I do not possess that "Amazing Kreskin" lobe in my Brain. So if you want better and more precise assistance... adding in exactly what you have done in the manner of testing or parts replacement, etc... as a preface to what you want to know will go a long way in cutting down how much time it takes to wade through any "Questions and Answers" before being able to get down to the very heart of the matter.
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