Adjustable Fuel Pressure Regulator???

[twoodson]

I have a 1987 Chevy 350 TBI and I am about to purchase an adjustable fuel pressure regulator. I was needing some suggestions as to which one would you guys suggest. cfm-tech.com has one from Turbo City for $73.95 and Summit Racing carries a JET (61500) for $65.69. Let me know what you guys think.

[TwinTurbo]

...or you could make your own adjustable, just take it apart, hammer out the plug on the bottom, tap it and thread in a screw. The other ones have thumbwheels for easier adjustment but a screw/bolt works just as well. If you have one of those bending screwdrivers they are pretty easy to adjust.

[1972C10]

Tools/Materials needed: T20 Torx bit (you can get away with an allen key but be carefull)
Dremel with a cutoff disk (optional) You also MAY need an injector pod gasket though most may not.

Step one: Disconnect negative battery cable

Step Two: Remove aircleaner assembly

Step Three: Remove gas cap to relieve system fuel pressure

Step four: Disconnect injectors and get the injector plugs out of the way aswell as the aircleaner stud (just turn it to face away from the injector pod)

Step Five: Remove the Eight (8) Torx screws on the top of the injector pod. Take note of the positioning of the 3 longer screws.

Step Six: With the screws removed from the top of the injector pod lift away the "roof" of the injector pod. Some fuel will leak out and be very carefull with the gasket so it does not tear or any debris fall into the path of fuel. The fuel pressure regulator is attached to it. It is the gold iridite "cup" looking object.
Take note of the tab sticking out of the fuel pressure regulator cup. This represents the range of adjustment. The higher the tab is the more compressed the spring is equalling more fuel pressure. You'll see what I mean later. GM seems to have no set fuel pressure as those who have performed this mod have all had varying fuel pressure settings from the factory.


Step seven: Now you will have to dissasemble the fuel pressure regulator. There are four torx screws holding the cup to the injector pod "roof". Slowly and evenly loosen the screws while maintaining firm pressure on the cup because it holds a spring under some tension. remove screws evenly while maintaining pressure. Once all 4 screws are removed carefully lift away cup. the spring will release tension and you may set it aside along with the injector pod roof.

Step eight: Take note of the fuel pressure regulators function. A small platform with a tab that sticks out the side of the cup rides on a threaded shaft. The higher the platform in the cup the more compressed the spring and the more fuel pressure is acheived.

Step nine: Now to make that threaded shaft movable and furthermore, adjustable easily. You will have noticed the shaft does not move. Flip the cup over and take note of the pressed in cap in the hole on the bottom of the cup. This must be drilled out. Its pressed in there quite well, and is not easy just to pull out. I and others have had to completely drill out the cap.
Be carefull so as to not exert too much pressure as it is possible to knock out the metal peice that is pressed into the cup on the bottom in which the cap sits


Step Ten: Now that you have drilled out the cap you will find that the screw and platform inside the cup are not only movable but removable from the cup. By turning the screw counter clockwise you raise the platform thus raising fuel pressure. You can raise the platform to a higher pressure and put it back together at this point but that takes away some of the adjustability to it.

Step Eleven: Now if you have a dremel with a cutoff disk this is much easier though you might be able to accomplish this with a hacksaw. Cut a slot in the head of the screw so that a small flathead screwdriver can turn the screw.

Step Twelve: Reassemble with a slightly higher fuel pressure setting. This time turn the cup around so that the tab does not face inwards and is not visible but faced out and is visible so that you can view the amount that the platform is raised. If you dont understand what I mean, just skip that.

Step Thirteen: Put injector pod "roof" back on top of injector pod. Be sure to snug down all screws to prevent leaks of fuel. REconnect Injectors, Put gas cap back on and reconnect negative battery cable.

Step fourteen: Start car with aircleaner assembly removed from car and watch for leaks from the top of the injector pod. No leaks? great! If you have a leak be sure you tightened the screws. You might need a new gasket. Most autoparts stores sell gasket material to make one or you can buy one from GM. You might also be able to find a gasoline compatible silicon sealer. BE CAREFULL THOUGH you CAN clog your injectors.

Step Fifteen: Put aircleaner back on and refer to TUNING WITH YOUR O2 SENSOR & DIGITAL VOLT METER in the tech section to be sure you have the right pressure! To re-adjust pressure its going to take you to remove the 8 screws on the injector pod roof again and just use a small screwdriver counter clockwise in the little slot you made to raise fuel pressure and clockwise to decrease it.
This article is for educational purposes only. Do not think about attempting unless you feel confident with your mechanical abilities and know the basics of your TBI unit.


You can read this as well as many other TBI mods here http://www.thirdgen.org/newdesign/tech/tbi-afpr.shtml

[TwinTurbo]

Wow what a write up LOL

[1972C10]

Well some people dont handle vauge directions very well so i figured i would post it.

[twoodson]

Thanks a bunch 1972C10, I may try thisdo it yourself mod or get the JET regulator and a tech guy at JET told me to drill about a 3/8" hole in between the two fuel lines that are connected to the TBI so it can be adjusted w/o removing the top of the TBI. I'm thinking about which route to go. That is a hell of a write up I need to see what tools I have and don't have.

[1972C10]

Yeah im going to try that method Posted on 3rd gen after i complete my TBI swap I was going to use a 454 thorttle body but i now hear that there are complications in wireing it up So i may just blend a stock tree fity one.