How To Diagnose A Bad Fuel Pressure Regulator (Andy’s Garage: Episode - 297)

[Music] welcome to andy's garage i'm andy phillips today i'm going to show you how to diagnose either a bad or a failing fuel pressure regulator with just some basic steps so let's go ahead and get started now to complete this these are the items that i recommend that you have they're not necessarily needed but it is recommended an obd2 scanning tool is definitely highly recommended whether it be a cheap one like shown here there's also bluetooth ones that you can get i did a product review on one you can check it out via the link above there's also more expensive ones but that's recommended because if you're getting a misfire or a lean or rich condition you want to be able to check the code itself to make sure that you're diagnosing things properly so that's highly recommended now you are going to need a fuel pressure testing kit like i have here for the for the fuel injection system because you want to be able to see how the fuel pressure is because one of the indications of a failing or or bad fuel pressure regulator is the actual fuel pressure even though that can be the case also with the fuel pump the symptoms are different so that that is definitely needed as well also going to need a rag and a flat head screwdriver so you can release the fuel pressure from the schrader valve that's needed as well and that's pretty much it now before we get started just to give a quick overview as far as what the fuel pressure regulator does just for your own understanding and this is just a very brief description in a nutshell what this does is this pretty much ensures that the fuel pressure entering the fuel rail system is the adequate amount needed for your specific vehicle for the fuel injection system so when these things fail a lot of times what will happen is the fuel goes directly into your system bypassing the injectors and that's what causes your misfires and other issues with the performance and in worst cases even stalling out so that's why it's so important to keep up on these make sure that it's always an optimum condition even if it's starting to fail but hasn't gone completely bad it's important if you're getting any issues to diagnose as we're going to talk about in this video and test it so that way you can swap it out before it does go completely bad and you wind up stalling out now some of the indications that you're having a failing or bad fuel pressure regulator is misfires misfires now that's where the scanning tool comes in handy because sometimes you can diagnose the misfire just by the performance of the car you might be kind of losing some acceleration it could be sputtering a little bit those you can be indications of misfires but if you have a scanning tool and you're getting a check engine light you want to check that because a lot of times your p 0 300 code so you have 301 302 303 and the the last digit is the cylinder that's having the issues so 301 would be cylinder 1 302 cylinder 2. now if you're getting a p0 300 that's a just a random misfire a lot of times that can be pointing to this guy right here the fuel pressure regulator because you're getting misfires all across the board so it's not one specific spark plug or ignition cable or cylinder that that's actually having the issue but it's all across the board and your ecu can't determine which once you get a random one so that's one of the issues as well so if you're getting that you may want to be thinking about these next following steps i'm going to talk about for testing the next thing that can also be the problem is getting some black smoke coming out of your tailpipe take a look at this video here now the vehicle that we're dealing with here as you can see we're getting a lot of smoke coming out to the point that it's even staining the garage floor and that's just from it idling it's not like it's been running for hours this is just starting the vehicle up letting it run the the smoke is getting thicker and it's actually staining the floor with that because of the black smoke that's a huge indication that that's your your fuel pressure regulator could be the culprit so the next thing you want to do at that point is now you want to connect your fuel pressure gauge to your schrader valve on your fuel rail and you want to test the fuel pressure and here's how you would do that here take a look and as you saw it does spray out a little bit so make sure you're not right in the path of that and it's not also a bad idea to put on some safety glasses before you do that make sure it's nice and tight and just hand tighten it and now we have our gauge connected here so we have the schrader valve we have the line coming right in to the gauge itself so now we can go ahead and what we'll do is we'll start the vehicle and you want to make sure for your vehicle that you see what is the required psi for the fuel pressure range for your for your particular car or or truck whatever you're working on so what we're going to do is we're going to start it and we're going to see where it falls in the range and then we're going to turn it off and see if it holds pressure if it's leaking pressure then we know that the issue could be with the fuel pressure regulator if it's off when it's running then it's probably the fuel pump so let's go ahead and start it and let's see what the pressure looks like and you can see the pressure right now of it running we're looking at kind of bouncing around right around maybe the 47 48 psi mark for this vehicle here so let's go ahead and turn the car off and see if it maintains the pressure and what we're running into here is that the fuel pressure is just kind of all over the place and it's below where it needs to be now that can also be an indication of your your actual fuel pump however one of the things at least for me that kind of differentiates whether it's the fuel pressure regulator or the fuel pump is if it's the fuel pump and you're on the road and you give it some gas you'll kind of have a little bit of it'll be weak as far as on the takeoff now in the case of this vehicle we're not running into that problem so the fuel pump seems fine also the fuel pump can also get noisy you'll hear kind of like a whining noise coming from the fuel pump that's another signal and then also you'll have the the fuel pressure as we saw will be below what's the required for your vehicle now another thing with this is that if you leave the fuel the the fuel pressure gauge connected you're running the car fuel pressure looks good or bad regardless when you turn the car off and you leave the gauge on your your fuel pressure should maintain if it starts to go down that's another indication that your fuel pressure regulator is bad as seen here coming under the hood now i want to show you an another telltale that it's bad if we remove this your your intake duct here's your throttle body if you go ahead and open right here just open the butterfly and i'm going to go ahead and we're going to open that up and i'm going to show you what's going on inside which is another major green light that the fuel pressure regulator is the cause so if we open this up i'm going to take my hand in here and it's wet and if you smell that that's actually gasoline so we're getting fuel getting into the throttle body which is not supposed to normally happen and that's also another clear indication that the fuel pressure regulator is having an issue in addition to that you may also have fuel inside the vacuum hoses so you want to check that as well now in some more excessive cases you can also have where the car won't even start you can also have back firing as well those are all indications that your fuel pressure regulator is in need of being changed um depending on how bad off it is whether it's just failing or whether it's completely gone will indicate you know whether you get some or all of these these um issues that that i mentioned so just wanted to kind of go over that so if you're running into any of those that's usually a clear indication that you might want to change your fuel pressure regulator now fuel pressure regulators they can be located in various spots on your vehicle if you're dealing with like i've dealt with some chrysler vehicles dodge jeeps things like that a lot of times the fuel pressure regulator and the filter are all housed in in one part and they're part of the the actual fuel sending unit that's inside the fuel tank so you got to you know drop the gas tank and all that stuff to get to it now in the case of the vehicle i'm dealing with here which is the general motors and on other general motors that i've worked on in the past the fuel pressure regulator is located just right around the fuel rail which makes it a lot easier because you're not having to drop the gas tank so what you want to do is you want to look around your fuel rail and and i'll show you here where it's located on this one but you might also want to do some research either a chilton manual a haynes manual or do some a google search to find out where it's located on yours but hopefully if you're having an issue with your fuel pressure regulator hopefully it's as easy as just being on the fuel rail because that makes it a lot simpler than dropping the fuel tank but let me show you where it's located on this one coming in here on the driver's side looking at the engine and this is a 5.3 liter v8 general motors engine inside of a chevy trail blazer we're doing a lot of work to this vehicle if if that's the vehicle that you're having the issues with i'll have links down in the bottom to all that i'm doing with this in case you want to drill in a little bit further but if you come along here here's one of the fuel rails you can see it right here runs along the back here's your vacuum line coming in here to your fuel pressure regulator and that's it right there so this one's very simple you just go ahead and remove the line pop the clip off pull that out put the new one in and reconnect everything you're good to go so that's kind of on on a general motors where it's located and like i said when you're looking at like a chrysler one and i'll show you a fuel pump assembly and show you what i'm talking about this is the fuel pump sending unit or or or fuel pump assembly off of a chrysler vehicle and what you have here this goes inside of the fuel tank whether it's a side mount or coming in from the top and then you have this part here where it gets clamped down you have the connection here to the fuel pump for the power and then this little guy right here see if i can remove it this is your fuel pump um i'm sorry that's your fuel pressure regulator and filter all in one so that's connected here that's connected here on this one right on the side so these are the ones that unfortunately you're gonna have to drop the fuel tank to remove the whole fuel pump assembly in order to get to that all right well this pretty much wraps up this video on how to diagnose a failing or bad fuel pressure regulator there's other things sometimes other factors that can go into that that i didn't cover in this video this was just kind of just a basic overview just kind of identifying some of the issues i'm dealing with on the one that i'm getting ready to replace i wanted to pass that along to you so if you have any questions or comments please send them in i hope that this video was informative i hope it helped you out with maybe any issues you're having with your fuel system as always i appreciate all the support so please like this video subscribe to this channel as i'm constantly posting content on a weekly basis and i'll see you next time you

Channel: Phillips Vision

Views: 356,112

Keywords: Phillips Vision, Andy's Garage, Andy PHillips, Andrew Phillips, automotive, cars, car, trucks, truck, fuel, fuel rail, fuel pressure, regulator, how to, diy, do it yourself, learning, easy, save money, diagnostic, diagnosis, helpful, fuel sending unit, fuel pressure regulator, performance, engine, misfire

Id: G6610136mjE

Length: 11min 23sec (683 seconds)

Published: Tue Nov 23 2021