Adjustable FPR, can't get below 46psi. WHY???
Thread Starter
Instructor
Joined: Jan 2008
Posts: 150
Likes: 0
From: West Newton Pennsylvania
Adjustable FPR, can't get below 46psi. WHY???
Since I changed injectors in my 88 coupe to Bosch III injectors from Jon at FIC, (car runs fantastic BTW) I also added an adjustable fuel preasure regulator. I can't get my fuel preasure adjusted below 46psi. I want to get it to the 43.5 that Jon suggest for my car. The car is running slightly rich, but goes like heck when you mash it. WHY? can't I get it lower. The adjusting screw is backed all the way out at 46 psi, and in danger of coming out of the housing, and will not go any lower.
Are there any members that have had a similar problem, or know what would cause this?
Thanks in advance. Jack
Are there any members that have had a similar problem, or know what would cause this?
Thanks in advance. Jack
Drifting
Joined: May 2008
Posts: 1,695
Likes: 490
From: Denver, NC
Since I changed injectors in my 88 coupe to Bosch III injectors from Jon at FIC, (car runs fantastic BTW) I also added an adjustable fuel preasure regulator. I can't get my fuel preasure adjusted below 46psi. I want to get it to the 43.5 that Jon suggest for my car. The car is running slightly rich, but goes like heck when you mash it. WHY? can't I get it lower. The adjusting screw is backed all the way out at 46 psi, and in danger of coming out of the housing, and will not go any lower.
Are there any members that have had a similar problem, or know what would cause this?
Thanks in advance. Jack
Are there any members that have had a similar problem, or know what would cause this?
Thanks in advance. Jack
Once you have the screw backed all the way out and the AFPR is on it's lowest setting, it is what it is. High pressure/volume fuel pumps will contribute to this as wll. I have seen this several times.
If you do have a high pres/vol pump in the car, you may find that a stock regulator gets overrun as well.
Also, the pressure setting changes with the vacuum line hooked to the regulator (it will be lower at idle with the line installed and higher with it removed)
Thread Starter
Instructor
Joined: Jan 2008
Posts: 150
Likes: 0
From: West Newton Pennsylvania
How, or where do I start to check for a restriction in the return line? I noticed the other night, I stopped for gas. When I went to take off the gas cap, there was a huge amount of preasure built up in the tank. I just cracked the cap, and it took about 20 seconds to release the preasure. Is this normal, or part of my problem. I know the adjustment screw is touching any thing in the adfp regulator, and its at 46 psi.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
Pressure in the tank is normal. Every time I unscrew my cap it does the same as yours.
When did you first notice the problem, was it there before the new FPR.
Did you measured the fuel pressure before all the changes you did?
Possibly the FPR is defective or range of adjustment is wrong for your set up. You might want to re-install the original FPR and see what the pressure is. This might assist you in finding the problem and you have the same pump as before.
When did you first notice the problem, was it there before the new FPR.
Did you measured the fuel pressure before all the changes you did?
Possibly the FPR is defective or range of adjustment is wrong for your set up. You might want to re-install the original FPR and see what the pressure is. This might assist you in finding the problem and you have the same pump as before.
Instructor
Joined: Dec 2006
Posts: 189
Likes: 2
From: Hinckley Ohio
I had this problem with one fpr that I bought. I do not remember the brand but it came with just the adjustable cap and a disc that you placed inside to allow the adjusting screw to depress the spring. This unit required that you use the original diaphragm and spring. With the screw backed out completely, the disc still had pressure on the spring and would not allow the pressure to drop.
I solved this by buying a Holley FPR that came complete with a new diaphragm and spring. With this unit I was able to fully adjust my fuel pressure.
I solved this by buying a Holley FPR that came complete with a new diaphragm and spring. With this unit I was able to fully adjust my fuel pressure.
Thread Starter
Instructor
Joined: Jan 2008
Posts: 150
Likes: 0
From: West Newton Pennsylvania
Pressure in the tank is normal. Every time I unscrew my cap it does the same as yours.
When did you first notice the problem, was it there before the new FPR.
Did you measured the fuel pressure before all the changes you did?
Possibly the FPR is defective or range of adjustment is wrong for your set up. You might want to re-install the original FPR and see what the pressure is. This might assist you in finding the problem and you have the same pump as before.
When did you first notice the problem, was it there before the new FPR.
Did you measured the fuel pressure before all the changes you did?
Possibly the FPR is defective or range of adjustment is wrong for your set up. You might want to re-install the original FPR and see what the pressure is. This might assist you in finding the problem and you have the same pump as before.
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Melting Slicks
Joined: Dec 2008
Posts: 2,772
Likes: 64
From: Mystic CT
Most of those are made assuming you want to raise the pressure so little concern is made for having stock pressure. the spring is either too stiff or the adjuster parts ave smimed the spring to a new higher pressure. You might try putting a gasket shim between the cover and body of the regulator to take some preload out of the spring.
Thread Starter
Instructor
Joined: Jan 2008
Posts: 150
Likes: 0
From: West Newton Pennsylvania
I had this problem with one fpr that I bought. I do not remember the brand but it came with just the adjustable cap and a disc that you placed inside to allow the adjusting screw to depress the spring. This unit required that you use the original diaphragm and spring. With the screw backed out completely, the disc still had pressure on the spring and would not allow the pressure to drop.
I solved this by buying a Holley FPR that came complete with a new diaphragm and spring. With this unit I was able to fully adjust my fuel pressure.
I solved this by buying a Holley FPR that came complete with a new diaphragm and spring. With this unit I was able to fully adjust my fuel pressure.
Thread Starter
Instructor
Joined: Jan 2008
Posts: 150
Likes: 0
From: West Newton Pennsylvania
!!! That don't sound good! Mine didn't come with springs. The only spring on mine is on the diaphram. All that was in the box was the cover, disc, and adjustment screw. Where are these springs suppose to go? 
Advanced
Joined: Nov 2008
Posts: 85
Likes: 1
I have this regulator - and it actually shows in the picture the other spring. One is good up to 20psi, the other from 20 to 60psi...
http://www.summitracing.com/parts/AE...1/?image=large
I suspect this is not the regulator you have based on you not being able to go below 46.....
Thread Starter
Instructor
Joined: Jan 2008
Posts: 150
Likes: 0
From: West Newton Pennsylvania
heh - it would depend on the one that you got....
I have this regulator - and it actually shows in the picture the other spring. One is good up to 20psi, the other from 20 to 60psi...
http://www.summitracing.com/parts/AE...1/?image=large
I suspect this is not the regulator you have based on you not being able to go below 46.....
I have this regulator - and it actually shows in the picture the other spring. One is good up to 20psi, the other from 20 to 60psi...
http://www.summitracing.com/parts/AE...1/?image=large
I suspect this is not the regulator you have based on you not being able to go below 46.....
Thanks,
Safety Car
Joined: Oct 2008
Posts: 4,689
Likes: 4
From: Yucaipa CA
tpi used different regulators for different pressures not sure what years they were different though. but if memory serves me right 85-87 was different then 88-up I think it's due to earlier tpi's having bosche injectors and the later multechs. I could be wrong though but maybe thats why you have the issue.
Melting Slicks
Joined: Feb 2006
Posts: 2,753
Likes: 15
From: backwoods upstate ny
btdt...cutting half a coil off the spring worked on one...bulldozed the spring on another by fully compressing it in the bench vise overnite (wrap a shop cloth around vice jaws/spring if you try this at home and don't enjoy spring hunting)
Le Mans Master
Joined: Oct 2008
Posts: 9,758
Likes: 49
From: Houston Texas
How, or where do I start to check for a restriction in the return line? I noticed the other night, I stopped for gas. When I went to take off the gas cap, there was a huge amount of preasure built up in the tank. I just cracked the cap, and it took about 20 seconds to release the preasure. Is this normal, or part of my problem. I know the adjustment screw is touching any thing in the adfp regulator, and its at 46 psi.
I took the return line loose and blew throught it. Now I can get my pressure down to 44 I couldn't get it lower than 50 before. There could also be rust in your return line.
Last edited by ch@0s; Jun 30, 2009 at 10:14 PM.
Thread Starter
Instructor
Joined: Jan 2008
Posts: 150
Likes: 0
From: West Newton Pennsylvania
I also have a TPI parts regulator. I noticed that with the spacer they give you, there is tension on the spring when you bolt it up. I tossed the spacer and bought a longer bolt. I don't remenber what size the bolt was but I think it was 1/2" longer it that helps.
I took the return line loose and blew throught it. Now I can get my pressure down to 44 I couldn't get it lower than 50 before. There could also be rust in your return line.
I took the return line loose and blew throught it. Now I can get my pressure down to 44 I couldn't get it lower than 50 before. There could also be rust in your return line.
Thanks...
Le Mans Master
Joined: Oct 2008
Posts: 9,758
Likes: 49
From: Houston Texas
I'll blast some air through the return line. There could be rust or something in there. This car sat a good bit before I bought it. As far as the longer bolt? Don't think that will work for me, because its backed all the way out. As soon as I turn it in, and it touches the diaphragm, it increases the fp. Its at 46 now. I want it lower, but not sure if 3 psi is enough to make it run rich.
Thanks...
Thanks...
Is your engine stock? what size injectors?
You Could also have a vacuum leak causing you to run rich, not uncommon with TPI.
Team Owner
Joined: Feb 2006
Posts: 24,460
Likes: 7
From: sw Ohio
tpi used different regulators for different pressures not sure what years they were different though. but if memory serves me right 85-87 was different then 88-up I think it's due to earlier tpi's having bosche injectors and the later multechs. I could be wrong though but maybe thats why you have the issue.