Fuel Pressure Monitoring
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Fuel Pressure Monitoring
How is everyone monitoring fuel pressure?
I came VERY close to blowing my car up on the dyno the other day because of a lack of fuel pressure under boost. I'm looking in to solutions now.
I came VERY close to blowing my car up on the dyno the other day because of a lack of fuel pressure under boost. I'm looking in to solutions now.
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Originally Posted by KPierson
How is everyone monitoring fuel pressure?
I came VERY close to blowing my car up on the dyno the other day because of a lack of fuel pressure under boost. I'm looking in to solutions now.
I came VERY close to blowing my car up on the dyno the other day because of a lack of fuel pressure under boost. I'm looking in to solutions now.
http://www.autometer.com/cat_gaugede...gid=2526&sid=3
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CJ Motorsports
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the problem is that fuel pressure is very dynamic, especially when you have a 1:1 ratio regulator. you cant really put a warning light on it unless you just pick a pressure like 30psi like he said about. problem is, if your pressure even drops 4-5 psi below where it should be at any given moment, you have problems.
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#8
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It really sounds like you should consider switching one of your gauges out and replacingit with a fuelpressure gauge.
If you have a fuel return system with a 1:1 regulator, your fuel pressure will fluctuate at least 20 psi. about -10psi (approx. 20 in.Hg of vaccum) at idle to + whatever your boosting. if you are boosting 10psi...then, you'd have a 20psi differential.
I think you should get a a defi BF gauge or autometer nexus. both of these have warning and record functions.
I'd recommend the cyberdyne because it has a hi and low memory recall along with a low pressure warning (flashing display), but I don't think the pressure transducer is accurate enough on the cyberdyne. It seems slow to react.
If you have a fuel return system with a 1:1 regulator, your fuel pressure will fluctuate at least 20 psi. about -10psi (approx. 20 in.Hg of vaccum) at idle to + whatever your boosting. if you are boosting 10psi...then, you'd have a 20psi differential.
I think you should get a a defi BF gauge or autometer nexus. both of these have warning and record functions.
I'd recommend the cyberdyne because it has a hi and low memory recall along with a low pressure warning (flashing display), but I don't think the pressure transducer is accurate enough on the cyberdyne. It seems slow to react.
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This is the problem I frequently run in to, because I don't want ANY guages. I have a boost guage and an A/F guage now, but neither can be seen while driving. They are only there for speriodic checks (they are under my armrest in my center console of my '04 G35 coupe). My car is my daily driver, and I strive to keep it looking as stock as possible, as to not draw unwanted attention from people who may see/ride in my car
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you are a handy guy.
make a gauge pod like mine for the G. People think it's stock. I even had an Infiniti dealer ask me if I'd make more of them. it took me about 2 hours to do this. By using a defi d-gauge, I was able to mount the gauge from behind, giving it more of an OEM look.
make a gauge pod like mine for the G. People think it's stock. I even had an Infiniti dealer ask me if I'd make more of them. it took me about 2 hours to do this. By using a defi d-gauge, I was able to mount the gauge from behind, giving it more of an OEM look.
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Usually the fuel pressure drop is caused by over-loosening your FPR adjustment screw, or a vaccum line that is dislodged, or you are in the process of running out of gas. Before a dyno session, I always blip the throttle, to insure that fuel pressure is, in fact, rising.
I simple in cabin fuel pressure gauge is a good idea, so you can make a quick visual check while making your dyno pulls. One other note: with our very sensitive siphoning systems, its a good idea to refrain from WOT pulls when your fuel tank is less than 1/4 full.
Hope that helps.
I simple in cabin fuel pressure gauge is a good idea, so you can make a quick visual check while making your dyno pulls. One other note: with our very sensitive siphoning systems, its a good idea to refrain from WOT pulls when your fuel tank is less than 1/4 full.
Hope that helps.
#12
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Originally Posted by Sharif@Forged
Usually the fuel pressure drop is caused by over-loosening your FPR adjustment screw, .
Most people are not aware that when setting your fuel pressure at idle, there is a point where the fuel return system cannot flow enough thru the return line to get the pressure to go all the way to zero. It will bottom out around maybe 40ish depending on your exact circumstances. If you continue to lower the set screw behind what it can flow at idle, when you start to burn more fuel by driving the actual pressure will fall to the setscrew setting. The symptoms of this will be the idle pressure being higher then your cruising pressure - assuming equal plenum vacuum when both samples are taken (if using 1:1 setup).
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Ineteresting that I NEVER thought about gas level. I was below a 1/4 tank. I am not above a 1/4 tank, I'll make some runs on my way home from work to monitor my A/F.
Things I have thought of -
Possible bad pump - tired pump not able to product full output (2 year old pump)
Bad regulator - Not sure how a regulator works, but there must be at least one moving part (spring?) that allows more liquid to flow when there is less resistance (higher duty cycle).
Fuel filter - restrict flow
Not enough gas - Sharif is smart.
Quadcam, I love that guage setup, IF I change anything I'll go that route.
In the mean time, I've came up with a plan to combat all my issues.
I ordered a fuel pressure sending unit that I plan to interface with a dedicated, custom, controller. I'll have a programmable low set point that will flash a yellow LED when fuel pressure is below setpoint. I will then disconnect my boost reference port on my regulator and retune my car. I don't need the boost reference anymore now that I have a UTEC, but I never eliminated it.
If anyone has a good reason why I should leave the boost reference on I have a few extra MAP sensors laying around that I could use to automatically adjust my 'low fuel pressure' setpoint to rise and fall with boost/vacuum.
Things I have thought of -
Possible bad pump - tired pump not able to product full output (2 year old pump)
Bad regulator - Not sure how a regulator works, but there must be at least one moving part (spring?) that allows more liquid to flow when there is less resistance (higher duty cycle).
Fuel filter - restrict flow
Not enough gas - Sharif is smart.
Quadcam, I love that guage setup, IF I change anything I'll go that route.
In the mean time, I've came up with a plan to combat all my issues.
I ordered a fuel pressure sending unit that I plan to interface with a dedicated, custom, controller. I'll have a programmable low set point that will flash a yellow LED when fuel pressure is below setpoint. I will then disconnect my boost reference port on my regulator and retune my car. I don't need the boost reference anymore now that I have a UTEC, but I never eliminated it.
If anyone has a good reason why I should leave the boost reference on I have a few extra MAP sensors laying around that I could use to automatically adjust my 'low fuel pressure' setpoint to rise and fall with boost/vacuum.
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Boost reference is important for an FI car. Otherwise, you are loosing actual pressure at the injector tip, even though your regulator is set at a fixed pressure. So definately keep the pressure line attached to your reg, so that your fuel pressure will rise 1:1 with boost.
#17
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Originally Posted by KPierson
I can't fix that by increasing my duty cycle under load?
You may also find, that even with a larger injectors, you will be reaching duty cycles that are pretty darn high. Lastly, your car will start and idle better with the vaccum line attached, is it will actually reduce fuel pressure and flow for you, to help start and idle the car more cleanly.
#18
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Originally Posted by VIZAGE
All this talk about fuel systems, what's the deal with CJ Motorsports? I called and said there # was disconnected. Trying to get there stage 1 kit.
#19
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Originally Posted by VIZAGE
All this talk about fuel systems, what's the deal with CJ Motorsports? I called and said there # was disconnected. Trying to get there stage 1 kit.
Of course, we have several dealers as well, essentially every sponsor of the forum here.