1FZ Fuel Pressure Testing

[tcorley37]

Hello fellow mudders!

I am curious if anyone has done fuel pressure testing on their 1FZ. I believe I may have a leaky injector, bad fuel regulator, weak fuel pump, or clogged filter. My 94’ 1FZ has lost power intermittently over the past month while the truck is under load, all at different speeds. I believe I have this issue down to a fuel problem. After reading some other threads, I am still unsure how exactly to test my fuel pressure due to their not being a schrader valve preconnected to the fuel line/rail anywhere. Any tips/pictures would be greatly appreciated.

 

[tcorley37]

I would also like to state that while testing my OBD1, the voltage on my oxygen sensors are great, jumping between 0.1-0.9. While testing my VF1/VF2 to E1, the voltage is 0.08v and 1.12v. Very low, after reading my ECU is adding extra fuel to the fuel/air mix. Could this be in correlation a potential problem listed above? Could replacing any of the things listed above solve the power cut out as well as the ECU needing to add extra fuel?

 

[ppc]

Hello fellow mudders!

I am curious if anyone has done fuel pressure testing on their 1FZ. I believe I may have a leaky injector, bad fuel regulator, weak fuel pump, or clogged filter. My 94’ 1FZ has lost power intermittently over the past month while the truck is under load, all at different speeds. I believe I have this issue down to a fuel problem. After reading some other threads, I am still unsure how exactly to test my fuel pressure due to their not being a schrader valve preconnected to the fuel line/rail anywhere. Any tips/pictures would be greatly appreciated.

There are some solutions for a pressure adapter/banjo fitting at the back of the fuel rail or another vaporware solution off the pressure regulator connection if you search the forum.

In the mean time I would hookup a wire from the FP terminal in the engine bay diagnostic connector running into the cab hooked to a volt meter and monitor the voltage going to the fuel pump. By design, the system operates under two voltages, controlled by the ECM. Monitor voltage to see if there is any correlation with the symptoms when they occur.

 

[Fj80oregon]

@cruisermatt i believe is selling these fuel rail adapters now?

 

[tcorley37]

There are some solutions for a pressure adapter/banjo fitting at the back of the fuel rail or another vaporware solution off the pressure regulator connection if you search the forum.

In the mean time I would hookup a wire from the FP terminal in the engine bay diagnostic connector running into the cab hooked to a volt meter and monitor the voltage going to the fuel pump. By design, the system operates under two voltages, controlled by the ECM. Monitor voltage to see if there is any correlation with the symptoms when they occur.

Used a voltmeter between FP and E1, during startup the volts measured 12v, then, during idle it sat around 9.2v. Seems to have the correct voltage. I am unable to drive the vehicle and view FP voltage at the same time so I assume that under high load, the voltage should increase to about 12-14v. FP voltage seems fine. How else can I compare the voltage to test the other potential problems listed?

 

[ppc]

I am unable to drive the vehicle and view FP voltage at the same time

Put the volt meter on the top left corner of the dash or get a passenger to monitor the meter.