I was told that you can increse fuel pressure by about 5psi by putting a washer under the spring. Is this true? Is this safe? Where exectly would I put this washer if it is true and safe?
Washers come in various thicknesses and yes, you could change your fuel pressure. The question is why? Do you have a more powerful engine? Fuel pressure and injector flow rates are about being right, more is just as much of a power killer as less. The only way to use more fuel is to produce more horsepower, or produce the same horsepower less efficiently.
It would be better to get an adjustable regulator, at least that way the pressure increase (or decrease) won't be so random as you would get with washers.
I have a 3.2 with a 260 cam and 15lb injectors. I also have nitrous. The reason for the incresed pressure was so that i am at 47psi at wot for sure.
https://www.fiero.nl/forum/Forum2/HTML/075042.html This is my thread that kinda explains my reason for trying to bump up the fuel pressure. The guy who told me to do it said use a nickle and it would be good for a few psi. I am going to see what my pressure is now and try and bump it up to atlest 47psi that way I can keep running my 22F jet.
[This message has been edited by goatnipples2002 (edited 07-13-2006).]
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08:15 PM
Blacktree Member
Posts: 20770 From: Central Florida Registered: Dec 2001
Somebody made a home-brewed adjustable fuel pressure regulator for me. He basically just drilled a hole in the top of the stock unit and welded on a nut. Turning the bolt (that goes thru that nut) adjusts the fuel pressure. Simple and effective.
Oh, about that nickel... I believe it should go between the spring and the top cover. The idea is to compress the spring a bit.
[This message has been edited by Blacktree (edited 07-13-2006).]
Isn't there just a spring under there? Is there a disc that the bolt pushes on?
My fuel pressure is 40 psi when I rev the motor to red line is that my pressure or do I need to have it under load (driving) to get an accurate psi. I didn't budge above 40psi.
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09:19 PM
watts Member
Posts: 3256 From: Coaldale, AB, Canada Registered: Aug 2001
Originally posted by goatnipples2002: Isn't there just a spring under there? Is there a disc that the bolt pushes on?
My fuel pressure is 40 psi when I rev the motor to red line is that my pressure or do I need to have it under load (driving) to get an accurate psi. I didn't budge above 40psi.
Stock, there's just the spring (which pushes against a disc at the bottom). You'd have to stick a shim up top, then weld on a nut, and run a wing bolt (for ease of adjustment!) into the nut.
To check your WOT pressure, just pull the "T" vacuum line off that feeds your MAP sensor - the other side of it goes to your FP Reg. It'll run like crap while it's off - but you're only doing it for a few seconds anyhow....
Okay I took the hose out that is attached to the "T" and it ran very rough, but if you say this is how you test WOT FP then my fuel pressure is about 42psi at WOT...I know it is specs but seems low. I will be modding my stock FP reg very soon. Til then I will just half ass it with some washers because tomorrow I am racing at the track.
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10:47 PM
Jul 14th, 2006
Pyrthian Member
Posts: 29569 From: Detroit, MI Registered: Jul 2002
Somebody made a home-brewed adjustable fuel pressure regulator for me. He basically just drilled a hole in the top of the stock unit and welded on a nut. Turning the bolt (that goes thru that nut) adjusts the fuel pressure. Simple and effective.
Oh, about that nickel... I believe it should go between the spring and the top cover. The idea is to compress the spring a bit.
yup - thats it. the pressure adjustment is the spring pressure. thats why the washer under the spring works too. and, for where you put the washer, you'll see right away when you pop it open. but, I do like the welding the nut on the top cover, and shooting a screw thru to adjust the spring. also - before you start thinking of it (I know I did...) - I really wouldn't trust epoxy
