Understanding how a fuel pressure regulator works.

Check out our new series called "How Not To Be An Idiot".
We geared this new series to help you guys understand misconceptions in the automotive industry. episode one Understanding how a fuel pressure regulator works.

[SonicFury]

So... Relatively speaking it does keep the fuel pressure constant, as a function of the manifold air pressure variable? Loving these videos so much.

[peterlogan]

Depends on if your pcm is set for vacuum/boost reference in the injector flow table to wether you connect the vacuum line or not

[jriggatx]

My mind was blown at 2:00. Yes, I am apparently an idiot, but at least I'm trying not to remain one :-). This was super helpful and to the point. Thanks!

[Bigblackee]

Studying for the army’s asvab auto&shop portion of the test. This helps me put what I read into pictures. ❤

[sardengineering]

Nice, brilliant technical introduction to differential fuel pressure and how it relates to dynamic engine loads 🙌🏼 This is a fundamental concept and your delivery was spot on for all levels 👌🏻

P.S. Love the engine simulator and gold box being used for your flow bench rig, would have been even better to see what fuel flow meter you were using 😊

[porkyjr]

Got a new subscriber as soon as you mentioned the title. I need this, quick and to the point, How not to be an idiot.

[georgecurtis]

Some systems had other ways of adjusting that and the fpr did not have a hose. So dont freak if yours does not. For some issues or to just give the car a bit of zip, one could up the fp a few psi. Fpr were on both electronic systems and mechanical fi systems.

[jamesmahle]

With all due respect, you have created a misconception; see beginning around 1:13: the pump sends fuel to the rail (not the regulator) and the regulator (at the end of the rail) regulates the pressure of the fuel inside the rail and if needed releases excess fuel via a return line to the fuel tank.

[Lordskeep]

Some fuel regulators are in the gas tank like in my ford explorer. Thus it has no vacuum line to adjust pressure. It uses a fuel pressure dampener instead.

[GregNConnie]

I've been having problems with a GM 350 Ramjet crate engine installed in my 58 Apache. The thing is sluggish on acceleration and uphill. I scanned the engine using ScannerPro and found out the manifold pressure was too high under load and the spark advance was too high.

I figured it was a vacuum leak and the base timing was off. I searched for a leak and the base timing was just fine. So, where do I go?

I just put a pressure gauge on the EFI rail and found out the fuel pressure dropped from 39psi to about 35/36psi at cruising rpm (2000).

Now that i watched this video, it makes sense now, the fuel pressure differential at high vacuum (lower psi on the rail) causes the engine to be sluggish on acceleration.

The problem may not be the pressure regulator. But I darned sure understand the problem now. That will make it much easier to diagnose.

[dionhamilton]

This was great. Thank you. Much informtive, very help.

[billybobbarker]

Ok good. I needed that. Today I found a teeny tiny vacuum line cracked on my gmc 5.3 that was sucking air. Trying to figure out it’s purpose. I finally got to understanding it to be the fuel pressure regulator vacuum line. So next I wanted to know if it mattered, that’s how I ended up here. Thanks. I will tape it up to repairs the crack for now, and replace it when I find a hose.

[danniiliasoff]

Short and informative. Thats how we like it. Great ideer 👍😉

[user]

Thank you please show more when it's working on the test bench

[frankvelasquez]

This excellent video definitely helped my idiot-itis symptoms!

[carlcraft]

can you show it in/on the vehicle instead of the bench mockup?

[paulwitte]

Im sorry but when you connect the FPR to your engine you shouldnt connect the vaccuum line (yet) because you wouldnt be able to tell the actual fuel pressure coming from the pump if the manifold vaccuum is meddling with the fuel pressure when idling. So first you hook it up, check and set the pressure without the vacuum hose and THEN you connect the hose for a proper working FPR.
Right?

[Simonstockton]

solid video really explains a lot. I am building a 1992 Celica with a Turbo charged 5SFE engine, i'm going to be using a Haltech elite 1500 to run it with 550cc injectors, walbro 255lph pump. Should be i looking at an AFPR too or will i be able to program this variable through Elite 1500?

[flyboyfs]

Nice work, one question, is there fuel pressure regulator for turbo aplication only? or all the same to non and with turbo aplication?

[MrYukon]

The vacuum line is only on boosted applications that is the boost reference you do not hook that up on a naturally aspirated vehicle.