What I'd like to know is if changing to a WalBro 255LH pump will increase FP over stock and if so by how much? Naturally this is based upon the assumption that the higher pump volume will exceed the oem in-tank FPR's ability to maintain the designed FP from the lower volume oem pump (160LPH?). TIA.

 

i dont believe it will. i just swapped my stock injectors back in and it still reads normal on off the factory ecu. although i cant confirm it bc i dont have a fuel pressure gauge, but based off of afr i think im still getting the same amount of fuel thats set by the factory ecu.

 

i cannot confirm either i do however run a 255LPH on my car at the moment and i have no power mods at this time, and the car runs fine. i get about 30mpg according to my scan gauge.

 

im doin the same thing except im still boosted. im only at 4psi on the stock injectors w a walboro 255. im gonna say its safe to assume that the pressure is regulated thru the ecu and how much it will let the injectors flow out. if this is the case than i dont see there being any increase in fuel pressure with just a pump.

 

Thanks guys. I really appreciate getting feedback from people who are actually running a 255LH with the oem FPR rather than speculation. I'd like to switch to a 255LH but I've been hesitant because AFAIK no one has ever done this on a XB without converting to a return system. Cory told me it's impossible but I don't think he tried very hard since he was installing 2 Walbros and a return system. Maybe I'll buy a used fuel pump assy and see if I can adapt a 255LH pump into it.

FWIW, I'm pretty sure that our ECU doesn't actively monitor or control fuel pressure as some other cars do. I believe ours is controlled soley by the in-tank FPR. I know there is no OBD2 PID for fuel pressure.

 

wouldnt it be regulated thru the maf and a/f sensor this way it knows how much fuel to add or subtract. i mean if u really think about it, thats one of the reasons why we change the voltage on the fic. ive noticed the higher the voltage @ idle, the more fuel it will add. so since the ecu will only output a certain voltage, it will only output x amount of fuel. not sure if this is worded correctly but u get the gist.

 

The ECU does regulate fuel delivery based on MAF, IAT, TPS, ECT, RPM and AFR sensor feedback but it does so by varying the fuel injector pulse width or "open" time. The ECU controls when and how long the inj's remain open but the fuel pressure remains constant or at least it should.

Some cars also use the ECU to control FP by varying voltage to the fuel pump but AFAIK ours does not do this. The ECU would need a FP sensor that we don't have.

 

thats exactly what i was tryin to say fred it just didnt come out that way.

 

i'd agree with that because my scan gauge doesnt pick up a FP signal.

 

in theory you can up the pressure if you can manage to "over run" the fpr, however pressure would not be consistant. In otherwords if you can flow more fuel than what the fpr can dump you would end up with a higher than normal fuel pressure. however it would require larger fuel lines (larger than what the opening on the fpr is) and one hell of a pump...lol

it would be easier to pop open the stock fpr and see if you can either shim the spring in it or swap out the spring. though this could be a problem as well cause if too high the whole fpr would just pop the eff out...lol

that could happen on the first case aswell. this is assuming the xb fpr is the same as the tc. The tc fpr is only held on the assymbly by an o-ring but that little sob is kinda tight. Also the fpr on the tc is two shells crimped togather so it would be a pita to pry apart and put back togather.

 

chris did you know you are a nerd?

 

iv always known this, but im the kinda nerd people like having around......................................
















.............................to fix their car

 

yea i need to fix my friends car. apparently a connector oxodized on the back of his ignition tumbler and now it's throwing bad resistances to the BCM in the vehicle thus not starting.

 

I've been told that I have a way with words... among other less flattering assessments...

Nothing here either. BTW, have you ever noticed your AFR getting rich immediately after filling the gas tank? Mine has done this since new. I don't even top off the tank but it still does it every time. It seems like it's either FP related or evap control.

 

AFAIK the XB fuel pump assy is different but very similar to the TC. As yet there is no replacement pump available for the XB and Cory told me that the assy could not be modified to fit a Walbro like you can with the TC. So far the only XB pump replacements I know of have been for return systems. Descendant has done this but they bypassed the oem FPR entirely.

Autospeed wrote an article on modifying returnless fuel systems where they slightly crushed the oem FPR in a vise (using appropriately sized sockets) to increase spring preload and resulting pressure. I considered trying this but the oem FPR is too expensive ($100+) for such trial and error mods. I'll probably end up with a return system of some sort, full or partial.

I got the idea that a higher volume pump might increase FP from Justin at P-Tuning but we didn't talk long enough to be clear about where and when his FP increased after adding a Walbro 255LH. It could be that his FP didn't actually increase but remained constant whereas it dropped off with the stock pump. That might be all I need but in the end I'll probably be much better off with a return system, RRFPR and full control over it. All I really want is to run my .5 bar WG spring instead of my .4bar spring. The last time I tried it I was seeing some erratic AFRs in boost (11-13:1) compared to 11-12:1 with the .4 bar spring. I only want to shave a couple tenths off my 1/4 ET to get into the 13's.

 

My wideband melted on my old exhaust so no I haven't noticed that.

Sent from my ADR6300 using Tapatalk

 

lmao

 

btw fred if I can find my stock fpr you can have it to play around with.

 

hey Fred right after I first installed the turbo, I went ahead and did a pump swap from stock to 255 walboro. Only thing I saw was a 6-8% drop in duty cycles and a tap bit richer in certain areas of the map. My guess because the extra flow and mainly the fuel delivery curve is different than the stock one. You should have no problems, just a tad richer than normal. Difference is I was able to change it with the fic.

 

fred I swear brother I always get caught up trying to read your post you have spent many years with computing and forum lifestyles that you use such big abbriviation hell it took me months to realise what you meant by AFAIK.

Btw not going to mention my name here but I'm that guy you sold an aem fic to about 2 years ago and I also came by again to pick up your old cx turbo