Fuel Pressure Regulator Mod - FREE
As you start moving to positive pressure (boost), you need to increase the fuel pressure to compensate. You may have heard of pressure increasing FMUs? Toyota came up with a fuel pressure that was best suited for the stock engine and fuel delivery. When you supercharge or turbo the engine, as the pressure goes above 0psi, you should raise the fuel pressure proportionally so that is best. However, there is another way that is free if you are mechanically inclined at all and it helps to have access to a air compressor.
After supercharging my engine and raising the boost to 7psi, I checked my fuel trims in closed loop and was shocked at the difference between bank1 and bank2. At this point, I decided to overnight Jim@ForeignAffairs' fuel kit and figured that alone probably wouldn't be enough. I was also convinced I would need more fuel pressure. So I took this apart thanks to Jim's instructions and watching Gadget replace my pump with the Walbro 190lph. I still wasn't sure, I'd know the regulator when I saw it or where I'd need to push in on it. So for those of you who are more visual like me, here is a pic of the assembly I am talking about. http://users.adelphia.net/~jbailer/Regulator_mod.jpg
To start with, you need to access the fuel sending unit assembly. It is under the rear seat. Grab the front of the seat and pull up and the seat will lift out. On the driver's side, you'll see the acccess door to the sending unit. It is stuck down with some black sticky stuff (the technical term
). Just pull up and it'll come off. Next there is an electrical connection. Unplug it, it's a little tricky but you'll figure it out. Next unclip and unplug the fuel line. Have a rag handy, fuel WILL come out. Not a lot but you don't want gas running all over in there. Then there are about a dozen screws holding the sending unit in. Although they have phillips heads on them, do yourself a favor and do NOT use a screwdriver, use a nut driver or socket for this job. Also be VERY careful not to drop them or you probably won't get them back. Have a bucket handy when you lift the sending unit out of there, you'll be dripping gas everywhere. Put the sending unit straight into the bucket, THEN take it out of the car to a suitable work area.
In the pic, the blue arrow points to the regulator and more specifically to the area you need to push on. You have to take the regulator off the assy, 2 screws. I took the head (part you would put the socket on) of the 1/4 inch socket wrench and put it in there. I put the other side of the socket wrench up against 1 side of a bench vise and put the other side of the regulator up against the other side of the vise and tightened. It's difficult to say exactly how far to press it in, my guess would be about 1/8". You can't push it too much or it looks like you'd mess it up. Hope the pic help. There is a spring right behind that hole. What you are doing is increasing the tension which changes the pressure the regulator opens up and allows fuel to flow. This is where the compressor comes in handy. What you want to do is push it in a little bit at a time until it gets to 59psi. If you push it to far, you can't pull it back out (at least not easily) so go carefully. Use an air nozzle and blow the air in the direction the fuel would go. When it just allows air to pass through right at 59psi, you know you have it pressed in right. I didn't have my compressor hooked up yet when I first did this mod so I just pushed it a little and guessed. Later I pulled it apart to check it and readjust if necessary but found it was exactly 59psi (got lucky).
While waiting for my fuel mod kit, I did another OBD2 scan and this made a HUGE difference. The 2 banks are much closer now. The extra pressure must have helped even things up. When I finished the job with Jim's fuel line kit, the difference was within 1%. -JoeB[/url]
After supercharging my engine and raising the boost to 7psi, I checked my fuel trims in closed loop and was shocked at the difference between bank1 and bank2. At this point, I decided to overnight Jim@ForeignAffairs' fuel kit and figured that alone probably wouldn't be enough. I was also convinced I would need more fuel pressure. So I took this apart thanks to Jim's instructions and watching Gadget replace my pump with the Walbro 190lph. I still wasn't sure, I'd know the regulator when I saw it or where I'd need to push in on it. So for those of you who are more visual like me, here is a pic of the assembly I am talking about. http://users.adelphia.net/~jbailer/Regulator_mod.jpg
To start with, you need to access the fuel sending unit assembly. It is under the rear seat. Grab the front of the seat and pull up and the seat will lift out. On the driver's side, you'll see the acccess door to the sending unit. It is stuck down with some black sticky stuff (the technical term

In the pic, the blue arrow points to the regulator and more specifically to the area you need to push on. You have to take the regulator off the assy, 2 screws. I took the head (part you would put the socket on) of the 1/4 inch socket wrench and put it in there. I put the other side of the socket wrench up against 1 side of a bench vise and put the other side of the regulator up against the other side of the vise and tightened. It's difficult to say exactly how far to press it in, my guess would be about 1/8". You can't push it too much or it looks like you'd mess it up. Hope the pic help. There is a spring right behind that hole. What you are doing is increasing the tension which changes the pressure the regulator opens up and allows fuel to flow. This is where the compressor comes in handy. What you want to do is push it in a little bit at a time until it gets to 59psi. If you push it to far, you can't pull it back out (at least not easily) so go carefully. Use an air nozzle and blow the air in the direction the fuel would go. When it just allows air to pass through right at 59psi, you know you have it pressed in right. I didn't have my compressor hooked up yet when I first did this mod so I just pushed it a little and guessed. Later I pulled it apart to check it and readjust if necessary but found it was exactly 59psi (got lucky).
While waiting for my fuel mod kit, I did another OBD2 scan and this made a HUGE difference. The 2 banks are much closer now. The extra pressure must have helped even things up. When I finished the job with Jim's fuel line kit, the difference was within 1%. -JoeB[/url]
- JoeB
- SolaraGuy Street Racer
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- Joined: Wed Apr 24, 2002 6:58 pm
- Location: Myersville, MD