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Ask Eric Gardner Your Own Question
Eric Gardner
Eric Gardner, ASE Certified Technician
Category: Nissan
Satisfied Customers: 198
Experience:  ASE, Bachelors Degree in Automotive Technology, Automotive Technician for 5 years
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I JUST CHANGED MY FUEL PRESSURE REGULATOR AND SPARK PLUGS

Customer Question

I JUST CHANGED MY FUEL PRESSURE REGULATOR AND SPARK PLUGS (NGK)....NOW MY 90 BASE 300ZX HAS ALMOST NO ACCELERATION.
JA: How many miles are on the vehicle? And when was it last serviced?
Customer: 167000....I also juse replaced both converterse and mufflers....it drove fine anti after the plugs and pressure regulator was replaced.
JA: What is the model of your '165000 Nissan?
Customer: 300zx non turbo automatic
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: I plan to fix it myself.....it idles fine and fuel pressure is 35psi. But it is harder to start now.
JA: Anything else you think the mechanic should know?
Customer: Fuel pressure drops to 0 immediately after ignition is turned off.
Submitted: 7 months ago.
Category: Nissan
Expert:  Eric Gardner replied 7 months ago.

Hello,

There are a few things that are happening. They all have to do with Fuel Delivery issues.

Your fuel pressure is low. It should be upwards of at least 55 PSI. If the fuel pressure regulator is new and it was working for a short time, then I would say that the fuel pump has gone bad. The fact that the fuel pressure bleeds off as soon as the ignition key is turned off, also tells me that there is an issue with the fuel pump as well. The anti drain back valve has failed in the pump which is why the fuel pressure drops off so quickly. With the ignition off the pressure should drop no more than 10 PSI from running pressure.

Please let me know if you need diagrams or instruction on how to replace the fuel pump.