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Discussion Starter #1
02 Tacoma 3.4 auto 190,000 miles

Over the last few years, my fuel pressure has been slowly declining to levels below factory specs. I believe factory specs are 38-42psi as measured on the fuel rail at the front of the motor.

I have a fuel pressure gauge permanently mounted as shown at the bottom of this page. http://www.gadgetonline.com/Gauges.htm. When I first installed it, fuel pressure was 38-39 psi. Now I'm reading right at 30psi. Thinking it was a failing fuel pump, I replaced it with no improvement in pressure.

No visible leaks or gas odors under the hood.

Any ideas ?
 

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02 Tacoma 3.4 auto 190,000 miles

Over the last few years, my fuel pressure has been slowly declining to levels below factory specs. I believe factory specs are 38-42psi as measured on the fuel rail at the front of the motor.

I have a fuel pressure gauge permanently mounted as shown at the bottom of this page. http://www.gadgetonline.com/Gauges.htm. When I first installed it, fuel pressure was 38-39 psi. Now I'm reading right at 30psi. Thinking it was a failing fuel pump, I replaced it with no improvement in pressure.

No visible leaks or gas odors under the hood.

Any ideas ?

Pinch the fuel return line for a few seconds with the engine running. Pressure should rise a few lbs over the "regulated" pressure of 42psi. If it does, the fuel pressure regulator is the likely suspect. If there is no change, the fuel filter could be getting plugged, possibly a leak in the tank (the short hose off the pump) or low voltage to the pump. Culprits here could be connections and/or the "circuit opening relay" that powers the pump.

FWIW a pump with 190K should be replaced as PM.
 

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im having similar issues ive tried everything but replace the fuel pressure regulator.

im having starting issues and full throttle issues hoping the new fpr will fix it.
 

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Discussion Starter #4
When I replaced the pump last week, I also replaced the filter. I'll try pinching the return line to see what it does. The short line in the pump still looked new and both clamps were tight.
 

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Discussion Starter #5
So I pinched the return line with caused the fuel pressure to rise, as expected. I'm guessing this signifies a failing fuel pressure regulator?

I plan on doing a throttle body/intake cleaning at the same time. Anything else I should be doing while the intake is off the truck?
 

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Are you taking the whole plenum off or just the intake tube and TB?
 

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Discussion Starter #8
New fuel pressure regulator didn't help. I'm going to see if I can find a manual fuel pressure gauge to test if my autometer gauge is still good.
 
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