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Discussion Starter #1
Anyone know what the fuel pressure should be on a b13 on the inlet line and the return line? Cant find it anywhere. Its a 93 sentra 1.6
 

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Sup Mod keeping the peace
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With the engine running, the fuel pressure at the output side of the fuel filter should be:
- with vacuum hose connected to the fuel pressure regulator: 36 psi
- with vacuum hose disconnected from the fuel pressure regulator: 43 psi
 

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Discussion Starter #3
With the engine running, the fuel pressure at the output side of the fuel filter should be:
- with vacuum hose connected to the fuel pressure regulator: 36 psi
- with vacuum hose disconnected from the fuel pressure regulator: 43 psi
Thanks my psi shot up with the vacuum hose connected
 

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Discussion Starter #5
Shot up to what pressure? With the hose CONNECTED, the pressure should drop down to around 36 psi. You may have a bad regulator.
this psi shot up to 47 with the hose connected ive been having issues with my car it cant get over 75 to 80 mph and my exhaust manifold where the o2 sensor is got CHERRY RED HOT so I think its a fuel issue causing the car to run lean spark plugs were a little white also I don't have a cat or resonator its been taken off the car is basically straight piped
 

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NF Mod/Nissan Master Tech
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If the fuel pressure is at 47 PSI with vacuum applied to the fuel pressure regulator and the engine is running, then the fuel pressure regulator is bad. Make sure vacuum is getting to the fuel pressure diaphragm as sometimes they can get clogged with carbon and need to be cleaned out. Make sure your exhaust is not restricted (maybe somebody stuffed a potato up your exhaust pipe?). Make sure your timing is good. There should only be pressure on the inlet side; there should be no or very little pressure going back to the tank on the return line.
 

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Discussion Starter #7
If the fuel pressure is at 47 PSI with vacuum applied to the fuel pressure regulator and the engine is running, then the fuel pressure regulator is bad. Make sure vacuum is getting to the fuel pressure diaphragm as sometimes they can get clogged with carbon and need to be cleaned out. Make sure your exhaust is not restricted (maybe somebody stuffed a potato up your exhaust pipe?). Make sure your timing is good. There should only be pressure on the inlet side; there should be no or very little pressure going back to the tank on the return line.
exhaust is straight piped no restriction what so ever and whats this fuel pressure diaphragm I know of the fuel pressure regulator and the fuel rail
 

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NF Mod/Nissan Master Tech
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I guess I should have re-worded that now that I re-read it. The fuel pressure diaphragm is inside the fuel pressure regulator. There is a vacuum hose that goes from the intake manifold to the fuel pressure regulator (technically, the fuel pressure diaphragm, but it's one and the same as the regulator). When running, there should be manifold vacuum at the end of the hose that connects to the regulator. If there is no vacuum, the port in the intake manifold is likely clogged with carbon build-up and needs to be cleaned out. If the regulator has no vacuum to it, it will run the fuel pressure at maximum pressure, or "pump pressure."
 

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Discussion Starter #9
I guess I should have re-worded that now that I re-read it. The fuel pressure diaphragm is inside the fuel pressure regulator. There is a vacuum hose that goes from the intake manifold to the fuel pressure regulator (technically, the fuel pressure diaphragm, but it's one and the same as the regulator). When running, there should be manifold vacuum at the end of the hose that connects to the regulator. If there is no vacuum, the port in the intake manifold is likely clogged with carbon build-up and needs to be cleaned out. If the regulator has no vacuum to it, it will run the fuel pressure at maximum pressure, or "pump pressure."
my issue is with the hose connected the psi is 47 my question is. is my fuel pressure regulator bad? and if so could this be a reason the car cant get over 75 to 80 mph
 
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