3FE Fuel Pressure Regulator Operating Specs (1 Viewer)

[NOLA78FJ40]

Trying to diagnose a running rich condition, rough idle with no codes; I suspect faulty fuel pressure regulator. I’m getting the following readings. Thoughts?

1) Diagnostic port short - 46psi (37-46psi)
2) Idling, vacuum removed - 46psi (37-46psi)
3) Idling, Vacuum reconnected - 47 psi (33-37psi should be range) - failed.

Is the last test the reason why it’s running rich, rough idle, with no codes?? Thanks! Any suggestions.

 

[NOLA78FJ40]

Darn - Now after testing again. The fuel pressure is lacking across the board. 26psi. Tried multiple times with 2 different gauges. Faulty fuel pressure regulator? Or fuel filter??

 

[Godwin]

FPR is mechanical so a failing one will not throw any codes pinpointing the FPR.

 

[NOLA78FJ40]

FPR is mechanical so a failing one will not throw any codes pinpointing the FPR.

That’s what I was thinking. I figured the EFI water temp sensor or an O2 sensor would trip a CEL code. I’m thinking this testing “exercised” the regulator and is now the regulator is really out of spec. Thanks.

 

[Godwin]

That’s what I was thinking. I figured the EFI water temp sensor or an O2 sensor would trip a CEL code. I’m thinking this testing “exercised” the regulator and is now the regulator is really out of spec. Thanks.

In the old days there was an email list called the 3FE List that was focused on FJ62s and FJ80s with the 3FE. I was an outlier on the the list with a 3FE swapped FJ60. Anyway, one frequent issue with a poorly running or non-running 3FE was a failing or failed FPR. I don't recall anyone testing the FPR or reporting any out of spec, the general rule was symptoms of a poorly running or non-running 3FE due to a fuel and replacing the FRP was the fix.

 

[NOLA78FJ40]

I’ve got a Delphi aftermarket FPR. I read the MR2 FPR will fit too. Should have some free time later this week to install. Hope the aftermarket FPR is reliable.

 

[Godwin]

Did you test the vacuum at the FPR (without looking at the FSM I don't if there is a test for vacuum or not), could be one other easy thing to check before swapping out the FPR.

 

[NOLA78FJ40]

Did you test the vacuum at the FPR (without looking at the FSM I don't if there is a test for vacuum or not), could be one other easy thing to check before swapping out the FPR.

 

[NOLA78FJ40]

There is vacuum source at the FPR (if I recall ~17) and applying additional vacuum (17+ with a pump) at the FPR does NOT cause FPR reading (now 26 psi) to change.

The FPR does hold vacuum with pump.
I just find it odd that diagnostic jump would first test 46psi fuel. Now I’m getting 26 psi fuel with diagnostic jump all around. Would the fuel filter suddenly clog at that moment? If it was previously clogged (that would be lean).

My brain is too tired to think of the causes other than swap out the FPR as all my plugs are sooted, mpg is sub 10mpg, roughish idle, and unburnt fuel smell in the exhaust, no codes. I’m sure there is a minor vacuum leak (I know, leanish) (sprayed everywhere), but will tackle that after this.

 

[cruisermatt]

Slow down.

Try another FPR. If you still have <40psi in the rail your pump is probably done.

 

[NOLA78FJ40]

Slow down.

Try another FPR. If you still have <40psi in the rail your pump is probably done.

FSM Indicates 33-37 at idle vacuum reconnected which is what I’m now getting - 37 psi. However, I’m now getting subpar performance with the diagnostic jump and have since ordered an oem fuel filter. The intank fuel pump is new (but aftermarket kit). The roughish idle is something else? But exhaust smell, plugs, sub 9mpg indictate richness. The engine kicks down to 675 rpm when it his operating (just below the first hash). Maybe o2 sensor?

 

[NOLA78FJ40]

Installed new Delphi aftermarket FPR. No change and I may install the OEM denso back in. Going to wait for the new OEM fuel filter that may just junked up at the right time. I pray the new fuel pump is not crapping out.

The engine runs, but I would like fuel delivery to be at specs for reliability. Of course the loan a tool from AZ is less than to be desired.

 

[overhanger]

In the old days there was an email list called the 3FE List that was focused on FJ62s and FJ80s with the 3FE. I was an outlier on the the list with a 3FE swapped FJ60. Anyway, one frequent issue with a poorly running or non-running 3FE was a failing or failed FPR. I don't recall anyone testing the FPR or reporting any out of spec, the general rule was symptoms of a poorly running or non-running 3FE due to a fuel and replacing the FRP was the fix.

3FE list - good times and good memories. Back then, an FPR replacement was not only easy and cheap it usually had positive results. So cheap, in fact, that testing was time spent wrenching when you could have been drinking high brow beer. These days an OEM FPR is something like $150 or more, so testing might be more practical. I find it interesting that the test specs shown above are listed under the FSM testing section regarding the cold start injector.
A friend just had his 3FE rebuilt and part of the rebuild was replacing the original OEM injectors with current day replacements which are spec'ed to fit 3FE and the Hilux 3.0 (slow) V6 engine. Turns out, these later injectors lowest flow rate flow considerably more fuel than the 3FE injectors do at full throttle and this truck would not pass emissions testing. Ran great, so different symptoms from the OP but notable just the same.

 

[NOLA78FJ40]

Case closed here. Fuel pressure tested OK per FSM. Leaving the new aftermarket FPR in unless suggested otherwise. Turns out the fuel pressure “loan a tool” had some issues. Still have that fluctuating RPM in idle at operating temp. but will tackle that vacuum leak with a smoker another day. Any suggestions??