Thread: Setting fuel psi?
07-02-2014, 09:46 AM #1
- Join Date
- May 2013
Setting fuel psi?
When should you set the desired psi of a static fpr?
When the fuel pump primes before starting ski?
When the ski is running at idle?
Lot of conflicting advice from older threads & Riva, anyone wanna clarify?
07-02-2014, 09:48 AM #2
07-02-2014, 10:20 AM #3
Technically speaking, "static" fuel pressure setting means with engine OFF and fuel pump on (start button pressed and DESS key inserted).
For those with a RRFPR (port connected), at idle there will be a vacuum on the reference line, thus diaphram pulls PSI out the system. The opposite while under boost. So to set true static it needs motor off.
The bigger debate is to have the reference port connected or leave open to atmosphere. Most tunes (Athena, some VTECH maps) have mapping based on a nailed down set PSI. However, depending on real world parameters and mods, you may want a reference line connected. VTECH specifically requested I run a constant PSI setting. Without a A/F meter/log there is no accurate way of knowing if connected/disconnected is best for your motor under your specific conditions.
07-02-2014, 10:37 AM #4
07-02-2014, 10:38 AM #5
I adjust my static fuel pressure when engine is at idle, fuel pump will be activated for a couple second when you put the key but then it will stop, I always adjust my fuel pressure that way.
From Riva instructions:
- Fuel Pressure Setting Instructions & Guide -
You must set and verify pressure when craft is running.
NOTE: In the Rising Rate configuration pressure is
raised at a ratio of 1:1. Fuel pressure increases 1
pound for every 1 pound of boost.
1. Hook craft up to flush kit.
2. Start craft’s engine and allow to idle.
3. Start water flowing to flush kit.
4. Hold adjustment screw using a 3/16” allen
5. Loosen jam nut using a 9/16” combo wrench.
6. Increase fuel pressure slowly rotating
adjustment screw clockwise. Reduce by slowly
rotating counter clockwise.
7. Tighten jam nut.
8. Rev engine up 2~3 times and allow to return to
idle. Verify gauge is reading desired pressure.
9. Turn water off.
10. Turn engine off.
07-02-2014, 11:13 AM #6
Set base PSI fuel pressure at idle. If you are running RRFPR with the intake hose hooked up, I normally ask the guy that sent you the fuel map. Typically I set it to about 35 PSI at idle with the hose hooked up at idle. That will give about 58 PSI in the rail at WOT.
Never assume the pressure stays at that static setting at WOT. If you FPR is too small or you fuel pump is going away, the WOT results can be very different.
07-02-2014, 12:32 PM #7
- Join Date
- May 2013
Thanks guys, this weekend sees all the mods finally on and the ceremonious closing of the two halves of the ski - yay. Re-flash of firmware @ v-tech office, fuel pressure set and then finally ready to hit the water and start tuning. Fingers crossed all thoses hoses, connections and fine wires I spliced with the CMD hold up. Can't be taking that deck off again this season, just wanna be ridin.
07-03-2014, 05:28 AM #8
Really u set it up to ur AFR reading ...
I have always done it with key on not idle , every one has their own way ...
07-03-2014, 06:58 AM #9
Last edited by Snoman; 07-03-2014 at 07:19 AM.
07-03-2014, 07:12 AM #10
58psi is not needed at idle
in fact with bigger injectors could cause more problems
remember under vacuum the injector will have even more nozzle psi
if you set the psi when the motor is not running or with the reference line off
will keep the max psi down under full boost
now if your injectors are on the small side then set the fuel psi with the motor running
I believe Andy miss typed the fuel psi at idle with reference working
he said 35 and I bet he ment 45
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