entropy
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posted September 12, 2005 11:36 PM
measuring fuel pressure????
I've screwed with/broken every other part on my heap, so i figure it's time to check the fuel pump/regulator. Maybe I can snap/crush/cross-thread/hook-up-wrong something on the fuel system.
Any tips?
VH, I know you did a PhD thesis on this but can't find the thread???
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TurboBlew
Moderator
BUSY DOING THE SCHIAVO
Posts: 4590
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posted September 13, 2005 03:13 AM
Marren Motorsports sells this if you were to consider making another fuel rail....
http://www.injector.com/fuelrails.php
coupled with this....
http://www.injector.com/fueldampers.php?PHPSESSID=877555cf9fe83f88fa797cf918acd67f
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entropy
Moderator
Posts: 8671
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posted September 13, 2005 03:54 AM
TB,
For quite a while I've been getting a "bumpy" looking hp curve from 10k+, maybe the pressure is pulsing in the rail and a damper would help??? hmmmm....
thanks for the post/info.
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zrxdean
Needs a job
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posted September 13, 2005 08:46 AM
Kevin invested in a zulu Snap-on fuel pressure tester and has played with it, he could prolly tell you what to avoid. SM2W - 904 389 1177.
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VincentHill
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posted September 13, 2005 10:35 AM
 Edited By: VincentHill on 13 Sep 2005 11:37
Funny Karl because as soon as I saw the title I said "Now that is something I have a lot of experience on (More than I wanted!)
I went to a speed shop and bought a fuel pressure gauge that goes to 100 or more PSI. It has an AN Fitting on the back and I used a "T" with AN Female fitting in the Middle and and 5/16 Pipe female on the ends and 2 Male 5/16 with one on each end. Put the end of the outlet on one side and a line to the pump on the other side.
Turn on the key and you will sww 42 PSI in about 1 second and it will stay there for 2 more seconds. I also measured the amount of flow. I also did this on the return side where I saw about 15 PSI at the return valve (Which I now understand does not exist on the 2002 or later. ) What do you want to know??
Remember in the end, my main problem was the routing of the fuel lines and with the tank up all was good. With the tank down, I pinched a line!
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entropy
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posted September 13, 2005 11:17 PM
VH,
Thx for the info, I will measure mine similarly.
I really don't think there is a problem cause my AF is fine on the dyno; i'm just "checking stuff".
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lonniemac
Expert Class
Posts: 225
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posted September 18, 2005 06:34 AM
hey guys what u think would happen if u ristricted the return some and bumped the pressure up to about 50 psi. i pinched my line to that and my throttle response was better. i do have a true custom map in now and i know bumping the pressure will need a new map but my thing is if the regulator maintains a around 43 psi then other than volume how will this pump give a good tune at top speeds on dry spray. help me? thanks.
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VincentHill
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posted September 18, 2005 06:45 AM
quote:
hey guys what u think would happen if u ristricted the return some and bumped the pressure up to about 50 psi. i pinched my line to that and my throttle response was better. i do have a true custom map in now and i know bumping the pressure will need a new map but my thing is if the regulator maintains a around 43 psi then other than volume how will this pump give a good tune at top speeds on dry spray. help me? thanks.
Only the 00 & 01 even have the restricted return line. If you removed the restriction the pressure would be lower not higher. Funny how the muzzy pump with higher pressure causes the engine to run Leaner and not richer
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entropy
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posted September 18, 2005 07:53 AM
Edited By: entropy on 18 Sep 2005 08:54
i thought i had posted my results but i guess not:
i blocked the outlet of the gauge and got 58-60psi on the Muzzy pump. I guess it is healthy, eh?
lonnie,
(this is my understanding, and NOT to be taken as fact  )
I think its about what max rate the pump can supply vs what max rate the motor is eating.
At low hp, with either the muzzy or the OEM pump, the rail pressure is easily maintained at 43psi to the injectors, dumping excess gas back to the tank via the regulator. With a Muzzy pump, it is just dumping at a higher rate.
At high hp (over 210-ish???), the injectors are spraying so much fuel that the OEM pump cannot maintain the 43psi in the rail. The Muzzy pump, putting out a higher pressure/higher flow rate, is capable of keeping the rail at 43psi.
Vincent? is this it???
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VincentHill
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posted September 18, 2005 04:29 PM
That is my basic understanding I got from reading Doug Meyer's article.
Since I am using a Bypass fuel regulator to operate my NOS, I needed the extra fuel for that. Remember I made a unit to hold the Return valve "Before" the fuel went to the regulator so the pressure is only 15 PSI, then I have no restriction at the tank. My engine has been detuned *Lower Compression) to where it is only making about 160 to 165 HP (20 less than max then the spray adds the extra 150. I figure it is a lot easier on the engine to treat the NOS Like a Turbo and lower the conpression.
The "TEST" is to have the Regulator in line (Stock one) anb run your bike WFO on the Dyno and see if the pressure drops, then you know you need the Muzz Man's Pump!
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