Effects of High Fuel Pressure
Effects of High Fuel Pressure After installing my Racetronix PnP kit, my idle pressure has been around 10psi too high. Its sitting around ~68psi. Will this have any ill effects on performance. My wideband will click over to a rich range pretty often, so I assume Im getting quite a bit more fuel than I need. Is this something that can be corrected mechanically, or is it tune related (ex possibly lowing the given injector rate to compensate for the increase of pressure?) Thanks for the help.
11 Second Club
Joined: Jul 2007
Posts: 126
Likes: 0
From: Bedford, IN
Sounds like you need to turn the pressure regulator down to 58PSI......hoping that you have one. At 10PSI more you are getting more fuel through the injectors then what you were tuned for.....
Yeah Ive noticed the gas mileage go down a couple mpg since the pump install. I have all stock fuel system besides the plug and play kit (replacement pump and wiring kit). I dont think there is an adjustable fuel pressure regulator on the stock setup, am I correct?
Actually........................the regulator in the bucket is adjustable. You need a tamperproof screwdriver, or allen wrench. It's the same one that is on the rails on a factory return style system, but no vacum line. I would take about 1/2 to 3/4 of a turn out with it.
You can adjust it, but before doing so, you should determine the cause.
I would tend to think something else is wrong.
A larger pump will increase the pressure up to approx 62psi at idle, but it will quickly come back down to 58 as soon as you increase the throttle opening. This is normal & reducing the pressure, will make it read too low off idle.
You situation is not normal. It should never go to 68, unless your gauge is off.... or you pinched the return hose above the tank or got something in the return line. Does your pressure come down when under load?
Also the whole mileage thing does not make sense.... increasing pressure to 68 from 58 would increase fuel flow approx 10%. The computer will easily compensate for this.
I would tend to think something else is wrong.
A larger pump will increase the pressure up to approx 62psi at idle, but it will quickly come back down to 58 as soon as you increase the throttle opening. This is normal & reducing the pressure, will make it read too low off idle.
You situation is not normal. It should never go to 68, unless your gauge is off.... or you pinched the return hose above the tank or got something in the return line. Does your pressure come down when under load?
Also the whole mileage thing does not make sense.... increasing pressure to 68 from 58 would increase fuel flow approx 10%. The computer will easily compensate for this.
Trending Topics
You can adjust it, but before doing so, you should determine the cause.
I would tend to think something else is wrong.
A larger pump will increase the pressure up to approx 62psi at idle, but it will quickly come back down to 58 as soon as you increase the throttle opening. This is normal & reducing the pressure, will make it read too low off idle.
You situation is not normal. It should never go to 68, unless your gauge is off.... or you pinched the return hose above the tank or got something in the return line. Does your pressure come down when under load?
Also the whole mileage thing does not make sense.... increasing pressure to 68 from 58 would increase fuel flow approx 10%. The computer will easily compensate for this.
I would tend to think something else is wrong.
A larger pump will increase the pressure up to approx 62psi at idle, but it will quickly come back down to 58 as soon as you increase the throttle opening. This is normal & reducing the pressure, will make it read too low off idle.
You situation is not normal. It should never go to 68, unless your gauge is off.... or you pinched the return hose above the tank or got something in the return line. Does your pressure come down when under load?
Also the whole mileage thing does not make sense.... increasing pressure to 68 from 58 would increase fuel flow approx 10%. The computer will easily compensate for this.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo The fact that the motor is accelerating alot quicker in the lower gear. Using more fuel in a shorter period of time.
Fuel starvation because the car accelerates harder in lower gears moving the fuel further toward the rear of the tank.
Also G-forces work against the fuel in the lines. The weight of the fuel tends to work against the direction of flow as the car accelerates.
Also G-forces work against the fuel in the lines. The weight of the fuel tends to work against the direction of flow as the car accelerates.
how can I fix this problem, doesn't matter if the tank is full of fuel or almost empty If I drop the pedal in second pressure tanks to 40psi, even when the second pump which is activated via hobbs switch comes on it still doesn't help bring the fuel back up. My buddy has a similar set up as mine, he has aftermarket fuel rails and his pumps are wired together so both are on all the time, he has a crap load of fuel
Last edited by 01boydws6; May 1, 2011 at 07:43 PM.
If I'm reading things correctly... you have 615rwhp? You are out of fuel pump. You cannot expect much over 550rwhp out of a single 255lph pump.
Give me a call if you want to discuss some pump options.
Give me a call if you want to discuss some pump options.
I haven't updated my sig. for a while, currently have twin 255's the single I bought from you right before the car went on the dyno, second is walbro gs342. The 615rwhp was with the single 255 pump and hotwire kit car was going lean above 5k so we stopped until I could get around to putting two pumps in the car. With the single pump I only saw a few psi drop on the gauge, ever since I put twin pumps in the car I have been chasing this dropping pressure issue so I have never put it back on the dyno.
I would look into the way you assembled the dual pump kit... There is likely a leak somewhere internally or a problem with the way the pumps are mounted causing them to starve for fuel.
I originally used a t-fitting and the flex line that comes with your pump kit. since I hade to cut off the flat surface and clamp around the ribs I figured I was loosing fuel there so I got a stainless steel y fitting and used rubber line (I forget what the rating is but its rated to be submerged in the tank) the first time I put that set up the line to the second pump got pinched, I fixed that and still have the issue. The y is mounted with about a 2" pc of hose to the top of the bucket and clamped at to the bucket and to the y then the off of the legs of the y are about 3" pcs of hose that then mount to the pumps.
On The Tree
Joined: Jun 2015
Posts: 113
Likes: 12
From: Hopewell Junction NY
Actually........................the regulator in the bucket is adjustable. You need a tamperproof screwdriver, or allen wrench. It's the same one that is on the rails on a factory return style system, but no vacum line. I would take about 1/2 to 3/4 of a turn out with it.
firmly believe that the factory fuel psi regulator is preset for the factory fuel pump output not anything bigger .