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Sam, Ford Technician
Category: Ford
Satisfied Customers: 327
Experience:  Ford Senior Master Technician
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98 escort zx2: the fuel pressure goes up to 40 psi..drops..crank

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I have a 98 escort zx2, the fuel pressure goes up to 40 psi when you turn on the ignition, it is supposed to be at 50 to 80. It runs at 31 psi good is 25 to 35. The problem is the psi drops all the way to zero fast after you turn off the ignition, you have to crank the engine to start it. I don't see any leaks in the lines, took out the fuel injectors and turned on the ingiton pressure drops but i don't see any fuel leaking from the injectors. Does the fuel pump have some sort of a check valve that could of failed or does the pressure sensor control the pressure even after the ignition is turned off.
HelloCustomer Please meet Sam and thanks for choosing Just Answer with your question. It does sound like you've performed a fuel delivery test very well in determining your concern. The fuel pressure regulator is only operational when the engine is running and is tested with the fuel pressure tester installed and with the vacuum source removed the fuel pressure will rise. This will be a functional regulator. The fuel pump does have a one-way fuel check valve incorporated within the assembly. Your answer is that the electric fuel pump, that is in the tank, is failing to maintain constant fuel pressure and will require replacement along with a new fuel filter. Hopefully, I have been able to help you out that you will "ACCEPT" and provide a positive feedback. THANKS! Please feel free to ask any furthermore questions on this post about your question even after you've accepted and thanks again for choosing Just Answer!......Sam
Customer: replied 8 years ago.
Thank you, XXXXX XXXXX also wondering if this could cause a 171 code one bank lean, is the o2 sensor only if both banks are lean? There is also a small crack in the exhaust manifold that I don't know if it could cause it.
No problem at all ...a cracked exhaust manifold will not necessarily provide a fault code or lead to one....however a restricted or low fuel pressure will provide a lean condition. the P0171 DTC,(Diagnostic Trouble Code). This code may also originate from an engine vaccum leak or failing MAF, (Mass Air Flow) sensor. With this type of code it's best to have the engine scanned to monitor those parameters. Simple checks that you can do are...with the engine to spray, in small spurts of carb cleaner, all around the intake manifold and air intake system to determine if there's a change in idle. This attempts to find a vaccum leak. The engine computer is sensing that there is un-metered air flow entering the air intake system or that there is not enough fuel pressure with this type of DTC. You can also remove the MAF sensor to clean it with MAF cleaner or an equivalent. The professional route though is to have the Escort engine scanned for readings. Hopefully, you'll "ACCEPT" by pressing the green "ACCEPT" tab and ask away if there's more questions. THANKS!....Sam
Customer: replied 8 years ago.
You're welcome! Please press the green "ACCEPT" tab so that I may receive credit for my time spent with you and please ask if you have more questions! THANKS! ......Sam
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