stock fuel pressure

[5150]

Basicly im trying to find out the stock fuel pressure for my 2003 evo8. I have my aeromotive fuel pressure regulator from my eclipse and sense the eclipse doesn't work i decided to throw it on the evo but i dont know the feul pressure.

So if any one knows it that would be great, i know on the eclipse it was 43psi, i think its the same on the evo but then again i dont know.

I also have some deson 650cc injectors and walboro 255lph from the eclipse just wanted to know if those would work on it to and if it was a good idea to put those on.

[Warrtalon]

I get confused as to why people do this. Why did you take it off your Eclipse and just automatically throw it on the Evo? I don't understand that. It is not helpful nor useful, and if you don't have the background information to even make sure it's working right, it could be a risky proposition.

As for the injectors and fuel pump, the same thing applies. It doesn't make sense to just take mods from another car and slap them on your Evo. Put mods on your Evo if you NEED them. You have _0_ use for the FPR. The fuel pump is a highly recommended mod if you're modded otherwise and boosting over stock. The injectors are not needed unless you overrun your stock injectors.

[EmeryatSTM]

I try to set them around 40 psi without the vacuum source hooked up. Start there. Warrtalon is correct though, without proper tuning it wont do a thing and can cause more problems then it is worth!


-Emery

[turbolarry]

It's the same as the Eclipse; stock fuel pressure is 43psi without vacuum.
The Walbro pump (GSS342) should work, just the pump you don't need the kit.
The Denso 650's will fit. Just make sure the o rings are still good and you have a way to control them.

[5150]

I have not installed anything yet it was just a question as to what the fuel pressure was and if the other items would work.

There not on the eclipse because im parting that car out.

But thank you Turbolarry for providing me with some usefull information.

[5150]

well the pump is actually a GSS341 its for a 1st gen eclipse but i had it in my 2nd gen and it worked fine, so im guessing it will still work.

[ghoonk]

Okay guys, need some advice regarding risking rate fuel pressure regulators, e.g. HKS fuel pressure regulator, SARD fuel pressure regulator.

When installing an adjustable fuel pressure regulator (FPR), many people make the mistake of setting the fuel pressure with the vacuum line on the FPR still connected. From what I now understand, the correct way is to set it at a fuel pressure high enough to get the engine running, then disconnect the vacuum hose on the FPR, THEN set the fuel pressure to the 'correct'/desired level before reconnecting the vacuum hose. This will typically cause the fuel pressure to then drop.

For the purpose of this question, let's say we set the fuel pressure to 2.8 bar (40.6 psi)with the vacuum line disconnected.

Now, according to a number of online references from FPR manufacturers, this means that the fuel pressure at WOT is 2.8 bar, and the idling fuel pressure should be lower. In many cases, this would be irrelevant since we should only be concerned with fuel pressure under throttle.

Now, with the understanding that

a. fuel pressure should be set in accordance with the target peak boost level (i.e. to provide the right level of fuel pressure at max boost), and

b. this seems to be consistent with the description of the purpose of the differential pressure warning lamp in the Defi Link Control Unit II,

what is the 'correct' fuel pressure to set (with the vacuum hose off) if I am running 1.5/1.6 (21.7-23.2 psi) bars of peak boost, assuming that I am using stock fuel injectors and a Walbro 255 lph fuel pump?

[turbolarry]

Originally Posted by ghoonk

what is the 'correct' fuel pressure to set (with the vacuum hose off) if I am running 1.5/1.6 (21.7-23.2 psi) bars of peak boost, assuming that I am using stock fuel injectors and a Walbro 255 lph fuel pump?

43 psi.

[ghoonk]

Thanks!

Question: why 43psi, and not, say, 48psi, or 35psi?

I'm trying to understand how this works and how the 'correct' pressure is calculated

[turbolarry]

The correct pressure has already been calculated for us by Mitubishi and accounted for in the stock fuel maps. If you raise or lower the fuel pressure at the regulator, it effects air fuel ratios everywhere; idle, part throttle and WOT.
Remember a 1:1 raising rate regulator means for every one pound of boost, it raises fuel pressure one pound. That 43 psi. jumps to 58 psi. at 15 lbs. of boost. With your goal of 21.7-23.2 psi., you should be seeing fuel pressure of about 65 psi.