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There are a few different active fuel pressure tests listed in the 97 Mazda 626 GF Work Shop Manual ( European ). The first two are an idle pressure test ( 30 - 36 psi ) and a fuel pressure regulator test ( disconnect vacuum from the FPR 37 - 45 psi ). These first two tests are listed as "Pressure Regulator" tests and it says to replace the FPR if not as specified.

Then there is a third test, the "Fuel Pump Maximum Pressure" test, in which the engine is off and the fuel pump is manually energized giving an expected value of 64 - 92 psi. For this it says to replace the fuel pump if not as specified.

One thing I noticed about the maximum pressure test, is that the WSM only ever calls for it when the idle pressure is below it's expected minimum value. It doesn't seem to be a stand alone test.One thing I noticed about the maximum pressure test, is that the WSM only ever calls for it when the idle pressure is below it's expected minimum value. It doesn't seem to be a stand alone test.

Why would the pressure with the engine off be so much higher than with the engine idling and the FPR disconnected from vacuum? I understand that the injectors are working, so that causes a certain amount of pressure decrease, but does that completely account for a theoretical maximum drop from 92 psi down to 37 psi? Or is something else going on?

Is it possible that the first two tests could be good and the third test fail and it still be a problem with the FPR? On the other hand, if the first two tests are OK, but the maximum pressure test fails, does that necessarily indicate a problem with the pump?

There are a few different active fuel pressure tests listed in the 97 Mazda 626 GF Work Shop Manual ( European ). The first two are an idle pressure test ( 30 - 36 psi ) and a fuel pressure regulator test ( disconnect vacuum from the FPR 37 - 45 psi ). These first two tests are listed as "Pressure Regulator" tests and it says to replace the FPR if not as specified.

Then there is a third test, the "Fuel Pump Maximum Pressure" test, in which the engine is off and the fuel pump is manually energized giving an expected value of 64 - 92 psi. For this it says to replace the fuel pump if not as specified.

One thing I noticed about the maximum pressure test, is that the WSM only ever calls for it when the idle pressure is below it's expected minimum value. It doesn't seem to be a stand alone test.

Why would the pressure with the engine off be so much higher than with the engine idling and the FPR disconnected from vacuum? I understand that the injectors are working, so that causes a certain amount of pressure decrease, but does that completely account for a theoretical maximum drop from 92 psi down to 37 psi? Or is something else going on?

Is it possible that the first two tests could be good and the third test fail and it still be a problem with the FPR? On the other hand, if the first two tests are OK, but the maximum pressure test fails, does that necessarily indicate a problem with the pump?

There are a few different active fuel pressure tests listed in the 97 Mazda 626 GF Work Shop Manual ( European ). The first two are an idle pressure test ( 30 - 36 psi ) and a fuel pressure regulator test ( disconnect vacuum from the FPR 37 - 45 psi ). These first two tests are listed as "Pressure Regulator" tests and it says to replace the FPR if not as specified.

Then there is a third test, the "Fuel Pump Maximum Pressure" test, in which the engine is off and the fuel pump is manually energized giving an expected value of 64 - 92 psi. For this it says to replace the fuel pump if not as specified.

One thing I noticed about the maximum pressure test, is that the WSM only ever calls for it when the idle pressure is below it's expected minimum value. It doesn't seem to be a stand alone test.

Why would the pressure with the engine off be so much higher than with the engine idling and the FPR disconnected from vacuum? I understand that the injectors are working, so that causes a certain amount of pressure decrease, but does that completely account for a theoretical maximum drop from 92 psi down to 37 psi? Or is something else going on?

Is it possible that the first two tests could be good and the third test fail and it still be a problem with the FPR? On the other hand, if the first two tests are OK, but the maximum pressure test fails, does that necessarily indicate a problem with the pump?

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There are a few different active fuel pressure tests listed in the 97 Mazda 626 GF Work Shop Manual ( European ). The first two are an idle pressure test ( 30 - 36 psi ) and a fuel pressure regulator test ( disconnect vacuum from the FPR 37 - 45 psi ). These first two tests are listed as "Pressure Regulator" tests and it says to replace the FPR if not as specified.

Then there is a third test, the "Fuel Pump Maximum Pressure" test, in which the engine is off and the fuel pump is manually energized giving an expected value of 64 - 92 psi. For this it says to replace the fuel pump if not as specified. 

One thing I noticed about the maximum pressure test, is that the WSM only ever calls for it when the idle pressure is below it's expected minimum value. It doesn't seem to be a stand alone test.

Why would the pressure with the engine off be so much higher than with the engine idling and the FPR disconnected from vacuum? I understand that the injectors are working, so that causes a certain amount of pressure decrease, but does that completely account for a theoretical maximum drop from 92 psi down to 37 psi? Or is something else going on?

Is it possible that the first two tests could be good and the third test fail and it still be a problem with the FPR? On the other hand, if the first two tests are OK, but the maximum pressure test fails, does that necessarily indicate a problem with the pump? 

There are a few different active fuel pressure tests listed in the 97 Mazda 626 GF Work Shop Manual ( European ). The first two are an idle pressure test ( 30 - 36 psi ) and a fuel pressure regulator test ( disconnect vacuum from the FPR 37 - 45 psi ). These first two tests are listed as "Pressure Regulator" tests and it says to replace the FPR if not as specified.

Then there is a third test, the "Fuel Pump Maximum Pressure" test, in which the engine is off and the fuel pump is manually energized giving an expected value of 64 - 92 psi. For this it says to replace the fuel pump if not as specified.

Why would the pressure with the engine off be so much higher than with the engine idling and the FPR disconnected from vacuum? I understand that the injectors are working, so that causes a certain amount of pressure decrease, but does that completely account for a theoretical maximum drop from 92 psi down to 37 psi? Or is something else going on?

Is it possible that the first two tests could be good and the third test fail and it still be a problem with the FPR?

There are a few different active fuel pressure tests listed in the 97 Mazda 626 GF Work Shop Manual ( European ). The first two are an idle pressure test ( 30 - 36 psi ) and a fuel pressure regulator test ( disconnect vacuum from the FPR 37 - 45 psi ). These first two tests are listed as "Pressure Regulator" tests and it says to replace the FPR if not as specified.

Then there is a third test, the "Fuel Pump Maximum Pressure" test, in which the engine is off and the fuel pump is manually energized giving an expected value of 64 - 92 psi. For this it says to replace the fuel pump if not as specified. 

One thing I noticed about the maximum pressure test, is that the WSM only ever calls for it when the idle pressure is below it's expected minimum value. It doesn't seem to be a stand alone test.

Why would the pressure with the engine off be so much higher than with the engine idling and the FPR disconnected from vacuum? I understand that the injectors are working, so that causes a certain amount of pressure decrease, but does that completely account for a theoretical maximum drop from 92 psi down to 37 psi? Or is something else going on?

Is it possible that the first two tests could be good and the third test fail and it still be a problem with the FPR? On the other hand, if the first two tests are OK, but the maximum pressure test fails, does that necessarily indicate a problem with the pump? 

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There are a few different active fuel pressure tests listed in the 97 Mazda 626 GF Work Shop Manual ( European ). The first two are an idle pressure test ( 30 - 36 psi ) and a fuel pressure regulator test ( disconnect vacuum from the FPR 37 - 45 psi ). These first two tests are listed as "Pressure Regulator" tests and it says to replace the FPR if not as specified.

Then there is a third test, the "Fuel Pump Maximum Pressure" test, in which the engine is off and the fuel pump is manually energized giving an expected value of 64 - 92 psi. For this it says to replace the fuel pump if not as specified.

Why would the pressure with the engine off be so much higher than with the engine idling and the FPR disconnected from vacuum? I understand that the injectors are working, so that causes a certain amount of pressure decrease, but does that completely account for a theoretical maximum drop from 92 psi down to 37 psi? Or is something else going on?

Is it possible that the first two tests could be good and the third test fail and it still be a problem with the FPR?

There are a few different active fuel pressure tests listed in the 97 Mazda 626 Work Shop Manual. The first two are an idle pressure test ( 30 - 36 psi ) and a fuel pressure regulator test ( disconnect vacuum from the FPR 37 - 45 psi ). These first two tests are listed as "Pressure Regulator" tests and it says to replace the FPR if not as specified.

Then there is a third test, the "Fuel Pump Maximum Pressure" test, in which the engine is off and the fuel pump is manually energized giving an expected value of 64 - 92 psi. For this it says to replace the fuel pump if not as specified.

Why would the pressure with the engine off be so much higher than with the engine idling and the FPR disconnected from vacuum? I understand that the injectors are working, so that causes a certain amount of pressure decrease, but does that completely account for a theoretical maximum drop from 92 psi down to 37 psi? Or is something else going on?

Is it possible that the first two tests could be good and the third test fail and it still be a problem with the FPR?

There are a few different active fuel pressure tests listed in the 97 Mazda 626 GF Work Shop Manual ( European ). The first two are an idle pressure test ( 30 - 36 psi ) and a fuel pressure regulator test ( disconnect vacuum from the FPR 37 - 45 psi ). These first two tests are listed as "Pressure Regulator" tests and it says to replace the FPR if not as specified.

Then there is a third test, the "Fuel Pump Maximum Pressure" test, in which the engine is off and the fuel pump is manually energized giving an expected value of 64 - 92 psi. For this it says to replace the fuel pump if not as specified.

Why would the pressure with the engine off be so much higher than with the engine idling and the FPR disconnected from vacuum? I understand that the injectors are working, so that causes a certain amount of pressure decrease, but does that completely account for a theoretical maximum drop from 92 psi down to 37 psi? Or is something else going on?

Is it possible that the first two tests could be good and the third test fail and it still be a problem with the FPR?

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