I have fitted a malpassi rising rate fuel reg a couple of months ago. This w/e I replaced the high pressure fuel pump and noticed first up when I was trying to start it that I had fuel leaking from the hoses going to the fuel filter (which is only a few months old). I'm assuming the new fuel pump is pumping a lot better than the old pump, therefore causing leaks that weren't there before. the car isn't starting and I was thinking that maybe, with the fuel at a higher pressure now, then maybe the fuel reg needs to be adjusted to compensate. Is this theory true?
If so how do I adjust the fuel reg to know it is a the right setting, I don't want to change the setting too far so as to lean the engine out.
What makes the malpasi rising rate ?
Chris
Quote:
Originally Posted by Sleek
I have fitted a malpassi rising rate fuel reg a couple of months ago. This w/e I replaced the high pressure fuel pump and noticed first up when I was trying to start it that I had fuel leaking from the hoses going to the fuel filter (which is only a few months old). I'm assuming the new fuel pump is pumping a lot better than the old pump, therefore causing leaks that weren't there before. the car isn't starting and I was thinking that maybe, with the fuel at a higher pressure now, then maybe the fuel reg needs to be adjusted to compensate. Is this theory true?
If so how do I adjust the fuel reg to know it is a the right setting, I don't want to change the setting too far so as to lean the engine out.
It just adds boost pressure to the base pressure (same as std)
If you had the pressure set correctly with the previous pump, the pressure should be the same with the new pump, it pays to get it checked though. as far as leaks go, I had lots of problems if my car was sitting for say 2 months it would leak from the filter hoses. would get under the car and tighten the hose clips and 6 months later it would leak again, I used new EFI fuel hose and new EFI hose clips, and hasnt leaked since.
If you fit one of these can you get more from the standard set-up than not fitting one at all, sorry to get of the topic but saved posting a whole new one, is there any advantage at all.
Yes, if you bump up the fuel pressure by say 10%, that allows you to run maybe 1.5 - 2 psi more boost, but the mixtures at idle and cruise (closed loop) will still be o.k, because the O2 / ECU can correct approx 10 - 15% on most cars. its a worthwhile mod when you have std injectors that are maxed out (14psi) and std ECU.
With the fuel pressure the best thing to do is to put a fuel pressure gauge just before the fuel rail, the pressure should be about 38psi at idle. If the rising rate reg rises at 1:1 which it should then for every psi of boost the fuel pressure should rise at the same rate, so if you run 15psi boost say then your fuel pressure should be at about 53psi at full boost.
As for the fuel leak they could be just old coroded hoses near the fuel filter and may just need replacing.
Don't the Malpasi's change with vacuum also (same as std), if you are running say 50lbs when car not running, when idling maybe 40lbs and under boost will be 50lbs + boost.
I dont really know Malpassis but i assume there the same, so the more vacuum there is the lower the fuel pressure. So if the engine is off you have zero vacuum, so the fuel pressure will be higher then at idle and then after that zero point the fuel pressure will rise even more with the boost. So yes what your saying is spot on but you probably wouldnt get a rise of 10psi (fuel pressure) between idle and zero vacuum
Excuse my Turbo ignorance, but would a Rising Rate fuel regulator be needed for something like a Turbo or Supercharger conversion?
Asuming i'm going to run a Vortech supercharger on about 12psi, with bigger injectors, and fuel pump.
The only reason really to raise fuel pressure is when youre maxing out, or reaching the limit of your current injectors.
If you fit bigger injectors (and ecu), you wont need to put a aftermarket reg on, unless youre maxing those out.... which you shouldnt if u chose correctly in the first place.
You should always use a rising rate regulator on a boosted car the reason being that, say for example you had a fuel injected engine that had a fuel pressure of 15psi at the injectors (very low i know just an eg) and this engine was also running a turbo boosting 15psi then at the point where the injectors spray into the inlet its 15psi boost pressure pushing against 15psi of fuel pressure, end result the injectors wont spray. That is why a rising rate reg is used cause it rises with the boost, so on a VL Turbo for instance at Zero boost you may have about 42psi fuel pressure but when you hit 15psi boost your fuel pressure will be 57psi (42psi + 15psi). Without a rising rate reg your fuel pressure would drop off as boost cam in causing your engine to lean out(not good).
