How to Test for a Stuck Open Fuel Pressure Regulator! [A ScannerDanner Premium Lecture]

A stuck open fuel pressure regulator can cause low fuel pressure on both return type systems and today's returnless systems
ScannerDanner Tools:
www.scannerdan...
www.amazon.com...
For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available at www.scannerdanner.com as an eBook or paper book.
Want even more diagnostic training? Whether you are a DIY trying to fix your own car, someone looking to become an auto technician, or a current auto technician that wants to get more into diagnostics, subscribe to ScannerDanner Premium www.scannerdan... There is a 14 day free trial.
On ScannerDanner Premium I will bring you right into my classroom at Rosedale Technical College. You will find page for page lectures taken right from my book as well as exclusive classroom type case studies. What is so special about these classroom case studies? I pull live problem vehicles directly into my classroom and we troubleshoot them in real time, using and applying the theory and testing procedures we learn during the classroom lectures. There is no better on-line training of how to troubleshoot automotive electrical and electronics systems anywhere!
Disclaimer:
Due to factors beyond the control of ScannerDanner LLC, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. ScannerDanner LLC assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. ScannerDanner LLC recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of ScannerDanner LLC, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not ScannerDanner LLC.

[@tylordupont2068]

Its crazy but every time i had a fuel issue that i ended up diagnosing it was a dead pump that would not pump fuel, but different circumstances different results, love learning new diagnosing processes, Danner your awesome

[@franciscallan2729]

I have been repairing cars for a over 30 years experience but the way your detailed explanation of testing and verifying your diagnoses is so needed in today's mechanics your a true treasure and thank you for your passion and acknowledging your mistakes thankyou for effort to show process with theory.

[@ScannerDanner]

Thank you very much!

[@Watchyn_Yarwood]

Another good argument for OEM parts.

[@namasteforgetmenot]

Another fine example of the diagnostic process start to finish. Thank you.

[@Akadectra]

Thank you for that interesting video. Your book reached me today and I am looking really forward to start reading it systematically and learning from it 👍👍. I will combine reading it with watching corresponding videos on YT. Best greetings from Bavaria/Germany 👋👋

[@ScannerDanner]

Thanks again! Looking forward to hearing more from you. My sister lives in Marburg btw. She teaches linguistics at a University

[@abdul-kabiralegbe5660]

Classic SD never gets old.

[@isalmankhan1]

AWESOME👍🏻👍🏻👍🏻 Very important case study👍🏻👍🏻👍🏻 SD please do some more video's with James Danner, it's been a while since we've seen him😍😍😍 Thanks for sharing SD, STAY BLESSED🙏🏻🙏🏻🙏🏻

[@mike-yp1uk]

Great depth of details for regulator function. Another great video.

[@djosbun]

I hope the other students treat Dan with respect. He’s no different than any of us and is doing his best to be a great diagnostician. 👍🏼

[@ScannerDanner]

Thanks! My name is Paul Danner btw 😉

[@djosbun]

@@ScannerDanner I was talking about the Russian student, not you Paul! LOL

[@ScannerDanner]

@@djosbun hahaha my fault. I get "Dan" so often. Yeah "Dan" my student was absolutely treated with respect and was one of the best students in that class!

[@dporrasxtremeLS3]

yeaa! Scanner...@@ScannerDanner

[@jamesdelon7331]

Another great diagnostic study

[@calholli]

What I would really love to see from you and other mechanics: is how do you organize, store and travel with all your diagnostic gear? I don't ever see much about this on any of the channels.. I've built out a pretty respectable kit now with a scope and 2 scan tools, and a bunch of banana jack fittings/wire and probes and needles. and piercing probes, etc.. pressure transducer, amp clamps and mulit-meters, etc. and I don't know where to put it all or how to make a mobile kit. I'm thinking about an old suitcase that I have -- or a duffle bag -- or an old gun carrier that has a lot of pockets.. I'm not sure yet. I'd love to see your kit and how you travel with all your diag tools. Are you just tossing stuff on your truck seat and going.. or just throwing it all in a cardboard box, etc? I'm hoping to develop a nice mobile setup that's easy to grab and go and I'll have everything I need already packed. Can you please mention or do a video showing the different ways you've traveled with your gear over the years, and just speak on it a little bit-- what works and what doesn't. I'd surely be grateful for the info.

[@Thumper68]

Tackle boxes for fishing come in so many sizes and shapes and can usually move dividers for what you need. Id look there if I was you.

[@calholli]

@@Thumper68 From what I've seen.. Everyone just uses a cardboard box and throws all their stuff in it. lol

[@spelunkerd]

Great lesson!

[@ColdWarVet607]

In the rubber wiper blade of windshield wipers there is a long, thin and narrow strip of metal that gives "backbone" to the rubber wiper. Pull this metal strip out when changing wipers, its perfect for cutting into test pins for relay sockets!!!!

[@robbieraychannel]

Great video as always Paul, I always suggest using a inline fuse pig tail with a low amp. fuse when jumping relays so if someone makes a mistake they might get away with it. Especially students who may not know the relay numbering system by heart. Rob.....

[@ScannerDanner]

You still risk cooking the computer driver. Even with a 1 or 2 amp inline fuse. The driver that controls a relay carries under 200ma normally. It can handle more but would most likely blow before the inline fuse

[@robbieraychannel]

Ah gotcha I guess it's better to just be sure they are correct. Thanks for the reply. Rob.....@@ScannerDanner

[@pauldavis8716]

Outstanding video

[@lupedelacruz4152]

What a great class Mr Danner thank you and God B U

[@johnchambers12]

If the spring was not bent it would have rolled during your regulator tear down, thank you for sharing this with all of us! Was that a dorman part?

[@ScannerDanner]

I'm not sure

[@Kebekwoodcraft7375]

Nice diagnostic 😊

[@Pablo_Automotive]

Thanks Paul 😊

[@carmo9693]

FYI, the dead head pressure can actually push the rubber check valve in the pump towards the pump, and then you get no fuel pressure at all. Been there done that on a Toyota original FP years ago, yup replacement was necessary at that point. My suggestion is see the pressure and relieve the pressure asap. Never did that again, seen the high pressure and let pressure off back to the tank, but it had a rubber hose.

[@TheWalterHWhite]

I always love diagnosing fuel issues (generally). People are so quick to condemn the pump or regulator, and rarely do they test powers and grounds. This is a soapbox issue for me obviously. Always always always test and/or inspect your P & Gs. Always question why the fuel pump failed. Is this just an old OEM pump, or did it burn itself up?

[@DuaneDonaldson]

Paul, THANKS for bringing this Premium Class out for Public viewing, cheers.

[@gunnar1911]

I had a fuel pressure regulator pop a diaphragm, and the vacuum line started pulling in raw gasoline until it hydro locked

[@hlq2action310]

Wow, a dead engine because of a bad press. reg.

[@gunnar1911]

​@@hlq2action310Yeah, it was my fault for bending the rod though. The engine died, and I kept cranking it as it filled the intake with gasoline.

[@Thumper68]

@@gunnar1911how did you not smell gas like crazy or notice cranking was getting harder?

[@gunnar1911]

@@Thumper68 it happened on the freeway. The car died, and like a dumbass I decided to crank it until it wouldn't crank anymore 🤦‍♂️

[@Thumper68]

@@gunnar1911 yeah I could see that. The first thoughts get off side of road with tons of cars flying by at 70

[@Thumper68]

5/16 on the hose clamp makes getting tight easy and quicker. Most cheap 5 in 1 screwdrivers are a great tool to have around because when bits removed they fit hose clamps perfect. Also many also have one side the bits a little smaller then other so fits smaller hose clamps most of the time. Standard is 5/16 though.

[@irelandryan]

Paul, long time follower. I found a tooling use that is safer than the jumper wire. It's a fuel pump bypass with an Amp loop built in. Made by innovative products of America part number 9038a. Or matco rebrands them.

[@ScannerDanner]

I have a uActivate made by AESwave that is THE tool 🙂 The one you're describing sounds like a copy of this tool

[@zachariajacobussiebert3459]

Paul thanks for the excellent video, I watch all the time here in the corrupt South Africa. Have you ever encountered a 02071 and 00153, I have 2.0 lt Jetta Mk5 TDI and after having to remove all the relays looking for other faults the wipers stopped working, all programs on utube suggest I have to replace the wiper module or is there away around this, as a pensioner this module is very expensive.

[@ScannerDanner]

Sorry, I have not. Thank you though!

[@martyisabeliever]

Paul... Would Dan Sullivans Load Pro doing a loaded voltage drop test at the relay terminals been safer and as effective as using a jumper wire and amp clamp?

[@ScannerDanner]

No sir as I needed the jumper wire to put my amp clamp around it to measure fuel pump current. The load pro tool is used in a completely different setting

[@christopherbrown5338]

Is there a brand you would recommend?

[@ScannerDanner]

For the part? No. There is so much junk out there today. Factory part when possible

[@christopherbrown5338]

@@ScannerDanner Toyota parts are crazy expensive but I do believe you get what you pay for. I'm chasing a similar problem on a 2000 toyota 4runner. It is crazy tight where that regulator is located.

[@erick440]

A old tech taught me. Hook up a clear vacuum line, sometimes they will randomly leak during operation, and you can see it

[@ScannerDanner]

Great tip

[@robertcharles8279]

A quick question being this is a very informative video would it be wise to check the fuel filter or replace it as well as check to see for any High ethanol content in the fuel

[@ScannerDanner]

Ethanol content would have no affect of fuel pressure, but for sure the fuel filter should always be considered for any low psi issue.

[@robertcharles8279]

@@ScannerDanner thanks for the info man appreciate it great video by the way I'm an old head probably as old as you maybe a little older but nowhere close to your experience but the more you teach and the more you showing your videos the more I get interested in more and more so thanks again man appreciate your help and your teaching

[@robertcharles8279]

@@ScannerDanner maybe I didn't say it right but I was trying to ask if the ethanol content would have anything to do with deteriorating the rubber diaphragm in the pressure regulator

[@ScannerDanner]

@@robertcharles8279 oh yeah! 100% the ethanol deteriorates the diaphragm

[@larrymclain]

It’s crazy how high pressure is now on these new systems!

[@Demonslayer18765]

Should see direct injection pressures those are insane

[@johnnyfivealiveable]

Hey Paul I have a quick question? Will a weak crank sensor signal cause a PO351 primary/Secondary circuit code?

[@johnnyfivealiveable]

A 2003 gmc Sonoma 4.3 v six

[@ScannerDanner]

On the GM systems, an extended crank time, caused by literally anything will cause that code. Step 1 for me would be to check your fuel pressure during cranking. On that model it should be min 60 psi and should get to that pressure immediately

[@jamesortega8681]

tryin to diagnose crank no start, so a weak fuel pump doesnt prevent the car from starting like your video it had a weak fuel pump but it started right away. i have spark

[@ScannerDanner]

You have spark confirmed and it is a strong spark? What is your fuel pressure? Will it start with carb cleaner sprayed into the intake?

[@bobgall863]

Is there a internal check valve in the pump that maybe leaking back

[@ScannerDanner]

That is one of the causes, correct, but we addressed that it wasn't that, and was indeed the regulator again. I mentioned pinching off the return line again after replacing it and it held, proving a leaking regulator (I didn't show it)

[@jaisonmiler903]

Any bad luck with delphi pumps on 04 Silverado only get 54 psi max

[@ScannerDanner]

Pinch off your return line momentarily and see if psi jumps up to near 100 psi. If it does, your pump is fine and you have a regulator issue

[@arthurbright1625]

Something I did not hear you mentioned a stopped up fuel filter or fuel in the vacuum line to the regulator or no vacuum on the vacuum line

[@ScannerDanner]

In this case, a plugged fuel filter would have made fuel pump current very high and would have slowed down the speed of the pump. I should have mentioned a plugged filter as a general rule anyway. As far as no vacuum to the regulator, that would have caused idle fuel pressure to be too high, not low. And fuel running into the vacuum hose (torn diaphragm) would have caused a severe rich condition, in fact, for how low fuel pressure was, for that to be the cause, it would have completely flooded the engine.

[@63mrl]

Couldn't a leaking injector permit the fuel pressure in the rail to drop?

[@ScannerDanner]

Yes! But rail psi would still drop with the return line and pressure line pinched off

[@MikeSmith-nu9wt]

So my 07 silverado 1/2 ton 4x4 4.8 litre , i looked here i looked there , i cojldnt find the pressure regulator , finally went to old reliable and looked it up , it's built into the fuel pump assymbly in the tank , so now i got the whole box off the truck , the frame cross members all got 3 years of michigan winter road salt , rest of its life was florida , that salt still got me , rusted the darn frame , cross members , leaf spring hangers and brackets , what a p.o.s. ... Wonder if tower industries built this flacky frame ? Looking for a florida truck now , everything else is good on it , i kept up with maintence , didnt catch that frame though ...oops ..only got 328,000 miles too , almost new still 😂

[@EliasRodriguez-n5u]

Have 97 expedition stalls after engine warms up

[@ScannerDanner]

Lol let me consult crystal ball

[@bernardaflores1720]

We just had a regulator from Oreilly's bad out of the box, cheap stuff know days.

[@banjohappy]

Nowadays, not know days.

[@nickayivor8432]

SUBSTANTIAL Sir ScannerDanner Thanks for sharing it ❤it From Nick Ayivor from London England UK 🇬🇧 ⏰️ 22:05pm Good Evening

[@Kebekwoodcraft7375]

Next step is dealer parts 😊

[@KAutoTech1]

What about that check valve in the fuel pump?

[@ScannerDanner]

The check valve in the pump is never involved in low pressure diagnostics, only when you have a bleed down issue is that a concern. We addressed that the bleed down was not from the pump check valve.

[@KAutoTech1]

Thanks for helpful video @ScannerDanner

[@guestguide2544]

Couldn't it be the one way check valve in the fuel pump allows the pressure to bleed off?

[@ScannerDanner]

Absolutely! I mentioned pinching off the pressure line and it still bled down, eliminating the pump check valve (I didn't show it, but mentioned it)

[@georgebell3964]

👍

[@chrishorning3937]

The problem with testing this way is a open regulator and a leak inside the tank present the same.

[@ScannerDanner]

For sure, with a returnless system when the regulator is built into the pump assembly, there is no separating test to tell you if it's the pump or the regulator, but it doesn't matter, they both get changed together

[@chrishorning3937]

@@ScannerDanner i know that pain, I have several Jeeps. Half returnless and the other with. Every time I'm having a problem with a returnless one and I change the regulator it only keeps for a short while, usually because the sock fell off.

[@ScannerDanner]

​@@chrishorning3937 some of those were returnless but only at the rail. The fuel filter contained the pressure regulator and there was a return line in that location. Got burned on a low pressure problem on one of those one time that had a stuck open regulator and I called a bad pump smh

[@chrishorning3937]

@@ScannerDanner i know which one you're talking about, I own one. My other returnless has the regulator on top of the pump unit, there's only one port.

[@throttlebottle5906]

good thing there wasn't leaking injectors, that pump was on a long time without engine running. 🙃

[@ScannerDanner]

Yeah, there were never any rich condition symptoms with this one, so that was never a concern

[@orionmyth]

Cap the hose 🤔

[@Mongasirishtwins]

I feel like this would be so helpful to me if you were a little more organized in your teaching.

[@ScannerDanner]

We were troubleshooting a live issue with a class. So it is unique in that approach. In other words, misdirection happens when you're not filming after knowing what the problem is.

[@prentissirby6674]

Dont forget the fuel filter

[@ScannerDanner]

For sure, but in this case with pressure being so low and fuel pump current being normal, a plugged filter was not possible. Thanks!

[@calholli]

If the filter was clogged, the current would spike a lot higher under the extra load. Similar to what a starter does on a relative compression test.

[@uncleronny6748]

Chinese junk is not a type of boat but car parts now.

[@ScannerDanner]

Agree

[@cowlumbus]

meh...you get what you pay for. Chinese make great stuff if the supplier is willing to pay for higher quality. So that thing is we tend to now only have OEM (overpriced) and complete junk with every supplier getting the same junk and not requesting something in between. We used to have this with Sierra marine parts but now they are starting to ship the low end china stuff you can get on Amazon/eBay most likely to be competitive.

[@RolandElliottFirstG]

"MaultIMeter ", The american language is so Odd.

[@ScannerDanner]

We all have a different dialect depending on where we live