Resolved EVO stock Fuel Pressure Regulator (FPR) does it work?

[ApexVIII]

ok so on my old evo, i droped in a 255, its normal to run it on the stock FPR,

and i know that the DSM ones you can not do that it will over run it, so my question is, who has tryed this and knows for a fact that it will work or it will not work.

i dont even know if it will bolt up, just a idea i had the other day.

Thanks

 

[1992awdlaser]

My friend alo has an evo IX with dual 255's and stock regulator. Works perfect.

On the 2g awd' it might or might not make a difference. The 2g awd has a saddle tank that has a siphon in it that equalizes fuel on both sides. This will cause high fuel pressure on a 2g awd even with an adjustable regulator. Some only need the one 255 to make the siphon become a problem. Most require more than a single 255. The siphon can be drilled out to fix that problem though. So if you drilled the siphon out to 1/8" then the regulator should work.

I have no idea if it will bolt on tthough.

 

[DSMunknown]

http://www.dsmtuners.com/forums/bolt-tech/273736-rewired-evo-ix-fuel-pump-stock-fpr.html

^ Post #19 and 24.

I'm about to test this out over the next couple months. Should be fun to see.

 

[turboglenn]

My friend alo has an evo IX with dual 255's and stock regulator. Works perfect.

On the 2g's it might or might not make a difference. The 2g saddle tank has a siphon in it that equalizes fuel on both sides. This will cause high fuel pressure on a 2g even with an adjustable regulator. Some 2g's only need the one 255 to make the siphon become a problem. Most require more than a single 255. The siphon can be drilled out to fix that problem though. So if you drilled the siphon out to 1/8" then the regulator should work.

I have no idea if it will bolt on tthough.

Does this apply to all 2g's or is this soley on teh AWD models.. I have a FWD and have enver noticed this. ALthough i get so sick of starving fuel on hard right hand turns (even on a full tank arghhh) I also can't get my FP too low, and if i do it rises right back up to 40-43 psi

 

[turbosax2]

Just the awd models since they have a saddle gas tank to clear the driveshaft. The siphon is needed to transfer fuel from one side of the tank to the other so the pump can pick it up. FWD's have a normal gas tank and do not have a siphon.

 

[DSMunknown]

It's only for the 2G AWDs. One point for the FWDs.

 

[turboglenn]

Yea, but our FWD's starve for fuel bad on right hand turns... i'm not liking the NECKCAR left turn only deal i get stuck with

 

[1992awdlaser]

Should have mentioned awd. Post has been edited for the few people that will search in the future.

 

[ApexVIII]

so very few people tryed this?

 

[logic]

ok so on my old evo, i droped in a 255, its normal to run it on the stock FPR,

and i know that the DSM ones you can not do that it will over run it, so my question is, who has tryed this and knows for a fact that it will work or it will not work.

You will overrun the stock FPR on a DSM with any pump larger than a 190lph. Logging fuel pressure will clearly prove this.

Actually, you'd overrun the FPR on the Evo as well, if it weren't for a rather clever dual circuit that Mitsubishi integrated; at idle, it essentially underdrives the pump so the FPR has less fuel to bypass, while under load it drives the pump at a proper voltage (it's been a standing project that I've had the backburner to make a note of voltage at the pump on my Evo VIII to see if it has a similar problem with wiring that the 1g and 2g have).

That dual relay is why you don't have fueling problems at idle and mid-shift on your Evo with a 255lph pump; the regulator on the Evo is practically the same as the old design, with a different mount for that oddball fuel rail they decided to put on the Evo.

 

[Icarus]

You will overrun the stock FPR on a DSM with any pump larger than a 190lph. Logging fuel pressure will clearly prove this.

Actually, you'd overrun the FPR on the Evo as well, if it weren't for a rather clever dual circuit that Mitsubishi integrated; at idle, it essentially underdrives the pump so the FPR has less fuel to bypass, while under load it drives the pump at a proper voltage (it's been a standing project that I've had the backburner to make a note of voltage at the pump on my Evo VIII to see if it has a similar problem with wiring that the 1g and 2g have). That dual relay is why you don't have fueling problems at idle and mid-shift on your Evo with a 255lph pump; the regulator on the Evo is practically the same as the old design, with a different mount for that oddball fuel rail they decided to put on the Evo.

Wow, that's pretty cool. This is the first time I've heard about this. I was thinking that maybe you could use one of these Holley Performance Products Adjustable Pressure Switch#15680NOS to switch the relay. Tap the intake manifold for 1/8" NPT or just put a barbed fitting on the end and run it off a vac line. Then buy the resistor from the 4g94 Lancer mentioned in the RRE link and then you could have dual a circuit control for the fuel pump. I would want to log everything before I tried doing anything the could kil the motor, but once fine tuned you could have an alternative to the $200+ AFPR. Just a thought.

 

[ApexVIII]

i see, thanks for the info!

 

[polarmoment]

Wow, that's pretty cool. This is the first time I've heard about this.

Really? That's pretty old technology. My 91 MR2 turbo has a system like that for the stock fuel pump. The ECU would release ground on a relay that would bypass the fuel pump resistor under boost.

If you do a setup like this though, you have to make sure that if the system fails, it defaults to full fuel pump voltage as the Toyota system did. you don't want to go into boost with only 8V on the fuel pump.

 

[Icarus]

Really? That's pretty old technology. My 91 MR2 turbo has a system like that for the stock fuel pump. The ECU would release ground on a relay that would bypass the fuel pump resistor under boost.

If you do a setup like this though, you have to make sure that if the system fails, it defaults to full fuel pump voltage as the Toyota system did. you don't want to go into boost with only 8V on the fuel pump.

Just seems odd that Mitsubishi would would wait to place a such simple system on their cars. Would have been nice on the 3kgt with it's pathetic 160lph fuel pump. I'm sure FPR overrun was one of the factors in choosing that pump.

In regards to that switch, they have both open and closed version of the same switch. You could even setup a series of switches and resistors to step up voltage as manifold pressure increases. That would also allow a buffer margin if one switch should fail. Sounds like a fun project to me.

 

[steve]

Just seems odd that Mitsubishi would would wait to place a such simple system on their cars. Would have been nice on the 3kgt with it's pathetic 160lph fuel pump. I'm sure FPR overrun was one of the factors in choosing that pump.

I would have responded back in 2008 if I have seen the post. The 3kgt has a similar setup. The ECU controls a relay that bypasses the resistor in the fuel pump power feed.

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The Stealth Technical Information Manual (STIM) has a lot of details that were left out of the DSM Technical Manual (DTM) and are useful reading for DSM owners.