High Fuel Pressure

Did a bit of testing today on my 2006 4.0 Tacoma. Fuel pressure was over 60psi while running, let it get up to temperature, high pressure persisted. I installed a new OEM fuel pump last August. Could the fuel pressure regulator on the fuel rail be the culprit?

 

60psi is not high.

culprit of what
the engine appears to be running

 

I've read that the 1gr-fe should run around 41psi. Just wondering why it would be over 20psi higher.

 

Check to see if the vacuum hose on the back of the air filter box is plugged in.

Still shouldnt be 60psi.

In these scenarios I try a second gauge, 60 is abnormal for most OEM pumps. I've had bag gauges lead me astray.

Why is it hooked up?

 

It is plugged in, that's what I thought too. I'll see if autozone or someone has one I can rent and hook it up. I've been chasing a no start condition that happens sometimes. Was trying to see if I was losing fuel pressure after shut down.

 

read where, the FSM or not the FSM

gauge could be a factor. Whatever a dealer has as factory special tool is typically gonna be high quality and expensive.

Never had an FPR fail but typically component failure on a low pressure fuel system means failure of duel delivery resulting in the engine dying or failing to turn on.

If you look at it one way, think of many other cars that have a $40 integrated fuel filter and regulator into one. When those get replaced, it's both getting replaced.
In the off chance it is possible to overpressure, that'd likely cause other issues. Like ECM detecting interference with AFR and ensuing CEL.

 

This is where I first saw the Psi numbers. That and a couple other posts here on the forum.

 

100% its 40psi. I can tell you if you raise it over 44psi, the regulator dumps it all straight into the tank.

 

Interesting! Well it seems I need to confirm with a second guage that this is indeed running high. Are there any glaring issues as to why it would be up in the 60's?

 

I could see how a return line clogging would raise pressure
but have also never seen a fuel line clog, as fuel is basically a cleaning agent

as opposed to DEF lines in modern diesels which crystallizes and clogs everything all the time

 

Could I disconnect the return line, pop the gas cap off and hit it with a little bit of air pressure to see if it's clear? That can't hurt anything can it?

 

honestly, for one, don't overpressurize it.
Shop air is 100psi, that the tank cannot handle.

It is common to try and clear DEF lines before replacement, using compressed, but with gentle finesse and a rag to prevent backsplash.

theoretically, a leakdown tester can be set to a certain amount of PSI with adjustable knob.

I'm not 100% sure how the lines work, or how Toyota does their measurements and fuel flush services for example. Have done this on other vehicles without an external regulator (only a couple connections), rather than separate regulator with more.
Last time I tried to run a can of BG through my truck, it didn't seem to take any which way through the hoses; ended up pouring it in the tank.
As opposed to, ideally, cleaner supply tool connected, and engine running idling off that with exhaust vent hose on to perform cleaning, until chemical finished.
At least one of those hoses direct back into the tank.
There's like up to 4, in drivers side area, beside engine, in fender area. Not sure if there's more anywhere beyond that.

 

How do you have the pressure gauge connected?
It should be teed into the fuel supply line going to the fuel rail. If you dead head it into the gauge it will read high (60~ psig), as the regulator will be out of the circuit when dead heading.

Tank >> Filter >> Pump >> Fuel delivery tubing >> Fuel Rail >> Fuel Rail Regulator ( Set to ~ 40 - 41.7 PSI) >> Return to tank.

If you tee into the delivery tubing the regulator still works and reads the regulated pressure ~ 40 - 41.7 PSI.

If you dead head a gauge at the delivery tube it reads full pump pressure ~ 60 PSI.

While idling:
Standard: (40.8 to 41.7 psi)
• If the pressure is too high, replace the fuel pressure regulator.
• If the pressure is too low, check the connection between the fuel hose and fuel pump.

Stop the engine.
Check that the fuel pressure does not change for 5 minutes.
Standard: (21 psi)If the pressure is not as specified, check the fuel pump, pressure regulator and/or injector.

 

This

 

This is the T connector set I used, had it connected to the feed side coming from the pump. I doubt the guage would be off by 20psi... Then again stranger things have happened.

I will order a fuel pressure regulator and see if that helps.

Thanks for all the help so far!

 

Well the new fuel pressure regulator seemed to do the trick! Brought the fuel pressure back down right around 40psi. Let it get to operating temps, shut it down and it held pressure just fine. Thanks for all the help!

 

Well done

 

were there any symptoms caused by the original regulator that you notice better now that it has been replaced

such as possibly a couple MPG improvement

 

I will see about MPG on this next tank. It feels smoother, especially going through the RPM on the highway. Might be a placebo effect, who knows.

 

what brand FPR did you use?
I see Toyota has it around $120

rockauto:
-economy, Walker, $65 (economy usually means crap)
draily driver:
-WVE (never heard of it) $84
-standard motor products (also never heard of it) $87
-Delphi, $88

then good old eBay and Amazon with decent prices but no way to know if it's counterfeit or not

according to the internet, OEM PN is 23280-31010

what's interesting about eBay ads, is they have the part
and the box
which is exactly how fraud could be done if one seeks to that, by:
-get cheapshit Aliexpress parts that are in demand, in bulk
-get the part box from Toyota, buy it, take a picture with Aliexpress shit
-then go return that box to Toyota
voila, "OEM parts for sale"

zoomed in on a pic of one. Said DENSO on top. Leads me to believe for some odd reason RockAuto doesn't have that.