fuel pressure question
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From: Catawissa, Pa
fuel pressure question
hey guys...
i have a question. what are some symptoms of too high fuel pressure? i wish i had a gauge but dont yet. and could high fuel pressure affect fuel mileage? im just trying to figure out an mpg problem i have been having. the frx was the last thing installed before fuel mileage went down. i cant imagine its that, but maybe we screwed something up with the spring in the regulator. i dont know...but thought id ask.
thanks alot...
chris
i have a question. what are some symptoms of too high fuel pressure? i wish i had a gauge but dont yet. and could high fuel pressure affect fuel mileage? im just trying to figure out an mpg problem i have been having. the frx was the last thing installed before fuel mileage went down. i cant imagine its that, but maybe we screwed something up with the spring in the regulator. i dont know...but thought id ask.
thanks alot...
chris
Last edited by brownie83; Feb 27, 2011 at 06:05 PM. Reason: wrong spelling
Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
Usually you'll see the symptoms during idle. You could always pull the FRX for a short time to see if you notice any changes.
Did you make sure you got the spring on the side of the fuel bowl centered in the FRX piece? There's a lip inside the hole that the spring might hang up on and compress too much, increasing the fuel pressure.
I've never heard of high fuel pressure causing poor MPG's, but I do agree it's best to start with the last modification since you noticed the issue.
Also check for boost leaks. Any signs of oil in the bottom of the fuel bowl? Maybe the slight bump in fuel pressure from the FRX made an injector o-ring finally let go. No fuel leaks, right?
Did you make sure you got the spring on the side of the fuel bowl centered in the FRX piece? There's a lip inside the hole that the spring might hang up on and compress too much, increasing the fuel pressure.
I've never heard of high fuel pressure causing poor MPG's, but I do agree it's best to start with the last modification since you noticed the issue.
Also check for boost leaks. Any signs of oil in the bottom of the fuel bowl? Maybe the slight bump in fuel pressure from the FRX made an injector o-ring finally let go. No fuel leaks, right?
You like apples?
Joined: Jun 2006
Posts: 220
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From: LL, BC
when I put my FRx in wrong had over 100psi I didn't notice any drivability issues. I did notice I had a couple fuel leaks around the bowl into the valley and was always doing mop up.............................
Post Fiend
Joined: Nov 2007
Posts: 9,549
Likes: 14
From: Payson, AZ
You don't have to remove the FRx FPR housing to check the spring. Just loosen each of the two screws a little at a time until you can see the spring. If it looks straight it is not hung up, but a slight bend will tell you it is hung up on the side of the housing. If it is hung up loosen the screws to the point where they are just barely holding the housing on. Then using a very small pick you can carefully free it. Been there, done that. When I cocked a spring my 100 PSI fuel gauge pegged.
Edit : I would also like to suggest to anyone reading this that if you are going to make mods that will have an impact on fuel pressure have a gauge to check the fuel pressure before and after the mod.
Edit : I would also like to suggest to anyone reading this that if you are going to make mods that will have an impact on fuel pressure have a gauge to check the fuel pressure before and after the mod.
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Posting Guru
Joined: Oct 2007
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From: Catawissa, Pa
Usually you'll see the symptoms during idle. You could always pull the FRX for a short time to see if you notice any changes.
Did you make sure you got the spring on the side of the fuel bowl centered in the FRX piece? There's a lip inside the hole that the spring might hang up on and compress too much, increasing the fuel pressure.
I've never heard of high fuel pressure causing poor MPG's, but I do agree it's best to start with the last modification since you noticed the issue.
Also check for boost leaks. Any signs of oil in the bottom of the fuel bowl? Maybe the slight bump in fuel pressure from the FRX made an injector o-ring finally let go. No fuel leaks, right?
Did you make sure you got the spring on the side of the fuel bowl centered in the FRX piece? There's a lip inside the hole that the spring might hang up on and compress too much, increasing the fuel pressure.
I've never heard of high fuel pressure causing poor MPG's, but I do agree it's best to start with the last modification since you noticed the issue.
Also check for boost leaks. Any signs of oil in the bottom of the fuel bowl? Maybe the slight bump in fuel pressure from the FRX made an injector o-ring finally let go. No fuel leaks, right?
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Thread Starter
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Posting Guru
Joined: Oct 2007
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From: Catawissa, Pa
You don't have to remove the FRx FPR housing to check the spring. Just loosen each of the two screws a little at a time until you can see the spring. If it looks straight it is not hung up, but a slight bend will tell you it is hung up on the side of the housing. If it is hung up loosen the screws to the point where they are just barely holding the housing on. Then using a very small pick you can carefully free it. Been there, done that. When I cocked a spring my 100 PSI fuel gauge pegged.
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Cargo Master
Joined: Apr 2007
Posts: 2,333
Likes: 1
From: St. Louis, Mo.
Not to jack the thread, my fp at idle is about 60. I dont have the frx mod,but am considering it. How much increase in fuel pres do you see after the mod? Do you notice better throttle response?
Post Fiend
Joined: Nov 2007
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From: Payson, AZ
"We have also machined the FRx block to provide from stock to 72 psi of fuel pressure."
Plus it comes with 3 FPR springs to adjust fuel pressure.
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Posting Guru
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From: Catawissa, Pa
hey guys...thanks for all the info. checked it after work and it looked a little crooked...so i used my knife to try and move it around...looks a little better now. the idle fluctuation also has decreased after trying to move the spring. dont know why but maybe i killed 2 bird. thanks again...
chris
chris