Installed my walbro today! NOS guys...fuel pressure question
01-25-2002, 07:05 PM
#1
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Installed my walbro today! NOS guys...fuel pressure question
ok..so Jason (MAX2000JP) and I installed my Walbro pump today...I got the 255LPH high flow. Anyway...we started up...and it's SILENT (good news!). idle fuel pressure only went up about 2-3 psi..and full throttle fuel pressure is at about 50-51 PSI.....anyway..then we try the 50-shot.....HOLY $HIT...it pulls like mad...but the friggen fuel pressure is at almost 100psi!!!!!!! So we put in the 70 shot....it pulls even HARDER...and the fuel pressure stays just below 100 psi again!!! I know this is WAY too high of fuel pressure for a 70 shot...so I need to know what I should do...should I go get a different fuel jet...if so..which fuel jet should I run with the 70 shot and the new pump (I'm currently running the jet that came with the kit.) also...what NOS and Fuel jetting should I use for the 100-shot when I buy the jets tomorrow 
Thanks guys!
Thanks guys!
01-25-2002, 08:08 PM
#2
Re: Installed my walbro today! NOS guys...fuel pressure question
Let me plagurize Thomas...
"This is probably the most important aspect when tuning your nitrous kit. The fuel pressure decides whether you are lean or rich. If you are on a stock fuel pump, you idle fuel pressure should be 38psi and WOT(OFF nitrous) should be 43psi. Once you upgrade your fuel pump, your fuel pressure will increase both at idle and at WOT. How much it increases depends on the condition of your fuel pressure regulator. In my case, it went up to 42psi at idle and 48psi at WOT. Ok, now for fuel pressure ON nitrous.
50shot, 62psi;
60shot, 67psi;
70shot, 72psi;
75shot, 75psi;
85shot, 80psi
100shot, 85psi
(These figures should just be used as a guideline; your optimum fuel pressure may be a little more or less. To find out exactly what fuel pressure is best for your car, you have to read your spark plugs.)
Your NOS kit probably came with a .042 jet that you were supposed to use in the bypass tee. This jet regulates the amount of pressure that is vented into the intake manifold. The more pressure that is vented off, then less fuel pressure you will have. Therefore, if your fuel pressure is too high, which means you are running rich, you will want to move up to a bigger jet in the bypass tee. If you are lean, then you will want to put a smaller jet in the bypass tee to bump up the fuel pressure some more. If you are at a .042 jet and you want to increase fuel pressure, just go to a .040 jet, see where that takes you, and then adjust accordingly. To drop the fuel pressure, you’ll probably have to go more than one size up. For example, when I was running my 100shot jet with a .042 fuel jet, my fuel pressure was over 100psi. To get it to around 85psi, I had to move my way up to a .072 jet in the bypass tee. Depending on your own fuel pressure regulator, you may or may not have to go up that much. You’ll just have to try and find out what works for your car. If a .044 jet isn’t lowering your fuel pressure enough then go up some more until it does."
"This is probably the most important aspect when tuning your nitrous kit. The fuel pressure decides whether you are lean or rich. If you are on a stock fuel pump, you idle fuel pressure should be 38psi and WOT(OFF nitrous) should be 43psi. Once you upgrade your fuel pump, your fuel pressure will increase both at idle and at WOT. How much it increases depends on the condition of your fuel pressure regulator. In my case, it went up to 42psi at idle and 48psi at WOT. Ok, now for fuel pressure ON nitrous.
50shot, 62psi;
60shot, 67psi;
70shot, 72psi;
75shot, 75psi;
85shot, 80psi
100shot, 85psi
(These figures should just be used as a guideline; your optimum fuel pressure may be a little more or less. To find out exactly what fuel pressure is best for your car, you have to read your spark plugs.)
Your NOS kit probably came with a .042 jet that you were supposed to use in the bypass tee. This jet regulates the amount of pressure that is vented into the intake manifold. The more pressure that is vented off, then less fuel pressure you will have. Therefore, if your fuel pressure is too high, which means you are running rich, you will want to move up to a bigger jet in the bypass tee. If you are lean, then you will want to put a smaller jet in the bypass tee to bump up the fuel pressure some more. If you are at a .042 jet and you want to increase fuel pressure, just go to a .040 jet, see where that takes you, and then adjust accordingly. To drop the fuel pressure, you’ll probably have to go more than one size up. For example, when I was running my 100shot jet with a .042 fuel jet, my fuel pressure was over 100psi. To get it to around 85psi, I had to move my way up to a .072 jet in the bypass tee. Depending on your own fuel pressure regulator, you may or may not have to go up that much. You’ll just have to try and find out what works for your car. If a .044 jet isn’t lowering your fuel pressure enough then go up some more until it does."
01-25-2002, 08:57 PM
#3
01-26-2002, 12:09 AM
#5
Re: Re: Installed my walbro today! NOS guys...fuel pressure question
Originally posted by MardiGrasMax
Let me plagurize Thomas...
"This is probably the most important aspect when tuning your nitrous kit. The fuel pressure decides whether you are lean or rich. If you are on a stock fuel pump, you idle fuel pressure should be 38psi and WOT(OFF nitrous) should be 43psi. Once you upgrade your fuel pump, your fuel pressure will increase both at idle and at WOT. How much it increases depends on the condition of your fuel pressure regulator. In my case, it went up to 42psi at idle and 48psi at WOT. Ok, now for fuel pressure ON nitrous.
50shot, 62psi;
60shot, 67psi;
70shot, 72psi;
75shot, 75psi;
85shot, 80psi
100shot, 85psi
(These figures should just be used as a guideline; your optimum fuel pressure may be a little more or less. To find out exactly what fuel pressure is best for your car, you have to read your spark plugs.)
Your NOS kit probably came with a .042 jet that you were supposed to use in the bypass tee. This jet regulates the amount of pressure that is vented into the intake manifold. The more pressure that is vented off, then less fuel pressure you will have. Therefore, if your fuel pressure is too high, which means you are running rich, you will want to move up to a bigger jet in the bypass tee. If you are lean, then you will want to put a smaller jet in the bypass tee to bump up the fuel pressure some more. If you are at a .042 jet and you want to increase fuel pressure, just go to a .040 jet, see where that takes you, and then adjust accordingly. To drop the fuel pressure, you’ll probably have to go more than one size up. For example, when I was running my 100shot jet with a .042 fuel jet, my fuel pressure was over 100psi. To get it to around 85psi, I had to move my way up to a .072 jet in the bypass tee. Depending on your own fuel pressure regulator, you may or may not have to go up that much. You’ll just have to try and find out what works for your car. If a .044 jet isn’t lowering your fuel pressure enough then go up some more until it does."
Let me plagurize Thomas...
"This is probably the most important aspect when tuning your nitrous kit. The fuel pressure decides whether you are lean or rich. If you are on a stock fuel pump, you idle fuel pressure should be 38psi and WOT(OFF nitrous) should be 43psi. Once you upgrade your fuel pump, your fuel pressure will increase both at idle and at WOT. How much it increases depends on the condition of your fuel pressure regulator. In my case, it went up to 42psi at idle and 48psi at WOT. Ok, now for fuel pressure ON nitrous.
50shot, 62psi;
60shot, 67psi;
70shot, 72psi;
75shot, 75psi;
85shot, 80psi
100shot, 85psi
(These figures should just be used as a guideline; your optimum fuel pressure may be a little more or less. To find out exactly what fuel pressure is best for your car, you have to read your spark plugs.)
Your NOS kit probably came with a .042 jet that you were supposed to use in the bypass tee. This jet regulates the amount of pressure that is vented into the intake manifold. The more pressure that is vented off, then less fuel pressure you will have. Therefore, if your fuel pressure is too high, which means you are running rich, you will want to move up to a bigger jet in the bypass tee. If you are lean, then you will want to put a smaller jet in the bypass tee to bump up the fuel pressure some more. If you are at a .042 jet and you want to increase fuel pressure, just go to a .040 jet, see where that takes you, and then adjust accordingly. To drop the fuel pressure, you’ll probably have to go more than one size up. For example, when I was running my 100shot jet with a .042 fuel jet, my fuel pressure was over 100psi. To get it to around 85psi, I had to move my way up to a .072 jet in the bypass tee. Depending on your own fuel pressure regulator, you may or may not have to go up that much. You’ll just have to try and find out what works for your car. If a .044 jet isn’t lowering your fuel pressure enough then go up some more until it does."
01-26-2002, 12:27 AM
#6
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ok...so my FP has pretty much nothing to do with the nitrous jet that I am running right??
so if I went and got a .72 bypass jet and ran the 70 shot...I'd be at like 85 psi right?? so maybe a .80 or something should put me about 72-74 psi??? do I have the idea here or am I nuts??? Maybe I'll need an even bigger jet
so if I went and got a .72 bypass jet and ran the 70 shot...I'd be at like 85 psi right?? so maybe a .80 or something should put me about 72-74 psi??? do I have the idea here or am I nuts??? Maybe I'll need an even bigger jet
01-26-2002, 12:36 AM
#7
Originally posted by BriGuyMax
ok...so my FP has pretty much nothing to do with the nitrous jet that I am running right??
so if I went and got a .72 bypass jet and ran the 70 shot...I'd be at like 85 psi right?? so maybe a .80 or something should put me about 72-74 psi??? do I have the idea here or am I nuts??? Maybe I'll need an even bigger jet
ok...so my FP has pretty much nothing to do with the nitrous jet that I am running right??
so if I went and got a .72 bypass jet and ran the 70 shot...I'd be at like 85 psi right?? so maybe a .80 or something should put me about 72-74 psi??? do I have the idea here or am I nuts??? Maybe I'll need an even bigger jet
01-26-2002, 12:51 AM
#9
Re: Get a fuel pressure regulator
Originally posted by 1MAX2NV
Having control over your fuel pressure is much better than trying to mess around with nitrous jet.
Having control over your fuel pressure is much better than trying to mess around with nitrous jet.
01-26-2002, 09:45 AM
#13
Senior Member
Join Date: Sep 2000
Location: NJ
Posts: 5,630
Re: Re: Re: Get a fuel pressure regulator
Originally posted by BriGuyMax
would one of those be useful on my car???
would one of those be useful on my car???
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