Fitting walbro fuel pump with no remapping/FSE
 

Just purchased a walbro fuel pump on the basis of better reliability than the OE item. Have not yet purchased an FSE, dont know wether i will really need it or not?

My question is would it be ok to fit the walbro pump without a remap or FSE? IE will there be any overfuelling/pressure issues?

Thanks.

nope you should just be limited by the injectors - you will just be giving them plenty to take from

There have been issues with the FSE's anyway so stick with stock FPR until you can get an SX.

F

Does the newage STi standard FPR work at a higher pressure than the WRX item, or are they the same item?

Nick

I am in the same boat so decided to buy a Walbro 190l/h High Pressure pump rather tha "classic" choice 255HP just in case there is any overfuelling issue (standard PPP ECU in my car and no chance for remap in the near future).
A friend with WRX MY97 has suffered big overfueling due to 255HP Walbro, he changed to 190l/h HP and his car drives much better and has at least 20-30% less fuel consumption.
Even STI upgraded fuel pump is 180lh/300Kpa which is about 180lh/43psi close to Walbro's 190HP supply!
JIM

Surely, if the FPR is doing it's job, it shouldn't matter fitting the 255l/h pump?

Matt :)

If the extra fuel is too much for your injectors/modifications and can't be flow back to the tank then yes you'll have problem but from what have seen in other cars it's very rare!
By the way I found in the net that standard WRX pump flows only 130l/h, quite low IMHO.
I'd like to hear also prof's opinions!
JIM

FPR is a restriction in the fuel line. Without being able to adjust it (i.e. stock) then a bigger pump will generate a greater pressure in the fuel lines and a corresponding rise in the amount of fuel injected per squirt.

Regards,

J.

I thought it regulates to a point, as in for example if the OE is fixed at 3.5 bar at idle (or whatever it is), then the internal valve regulates to that level, irrespective of the pump flow rate?

If the stock pump is 130 lph it must be able to make more pressure than 3.5 bar at idle, otherwise the FPR wouldn't need to regulate.

As Jim has suggested, perhaps 255 lph is too much flow rate for the OE fpr to handle (just can't bleed enough away) but can cope with 190 lph.

Thats how i see it?

[QUOTE=Jay m A]

As Jim has suggested, perhaps 255 lph is too much flow rate for the OE fpr to handle (just can't bleed enough away) but can cope with 190 lph.

[QUOTE]

Hence my question about the STi version. Is the STi (UK) fuel pressure maintained at a higher pressure than the WRX. If so then getting hold of an STi FPR may be a cheap option than an SX or FSE?

Nick

I really must get round to installing my FP Gauge!!! :)

Matt :)

Does anyone remember the pressure of factory WRX regulator?
I guess it's about 300KPa=43,5psi as Subaru rates any uprated fuel pump in this pressure.
At 43,5psi a Walbro 190l/h High pressure gives about 176-180l/h, an uprated STI 180l/h and a Walbro 255 High Pressure about 251l/h, huge difference ah?
This is what I found searching the net, although it gives lower figures than what expected from each pump:

http://img.photobucket.com/albums/v4.../fuelpumps.jpg

Hope this helps in your decisions! :)
JIM

Just a comment : classic Impreza as well as buggedeyes are fitted with a 60L/H fuel pump. New age STi8 and WRX04 are fitted with 130L/H.
AFAIK, fitting a walbro 255L/H with no other mods to any of these cars doesn't cause any problem and shouldn't modify the fuel mixture

I would not have thought swapping the pump for an uprated one could adjust the mixture but what it can do and has done is be too much for the standard fpreg so check your fuelling.
In my case i did both and noticed you can squeeze a bit more fuel through your system by adjusting the reg..(and my pump was noisey so needed it)
People have made comments about the fse failing but doesnt that happen with a lot of things people try on here !

There are different stock pumps on classics so the chart may not be accurate for all cases.

F

In theory the FPR will still regulate the fuel upstream (coming from the pump) at the same pressure. There will just be a greater flow through the system.

Fitting the uprated Walbro with or without an adjustable fuel pressure reg will cause problems of over fueling in the open loop areas of the fuel maps, the ecu does not adjust fueling on open loop but reads directly from the maps. So whichever model year car you have then the fueling will change when one of these is fitted.

bob

Bob, I've just fitted a 255 walbro on stock reg. Will I need to do anything or will it just over fuel but be safe before a remap?

F
PS I'm doing a track day later this month.

My logic says that Bob is correct (is there any case for the opposite? :)), when you have bigger supply of fuel that should pass the same hole this means more fuel, as simple as that, ECU only reads from maps doesn't adjust when on open loop!
You can easily see if your new pump is much bigger than what you need by seeing fuel correction on closed loop or idlle.
That's why I decided to go the 190l/h HP route!
For those interested the new Walbro 190l/h HP pump is F20000141 for the pump or FPS201 for the kit.
JIM

Ah, if that's the case, then it's cleverer than I thought. From what BR wrote it looks like we might both be right though :)

Floyd it will over fuel, you may feel it choking up, if in flowing more into the same pressure the orifice diameter in the reg is insufficient to cope with the fuel flow then the pressure will increase in the rails, this will then force more through the injectors as the pressure drop across them has increased. In practice the std reg is fine if remapping, if not then expect the car to run richer, on closed loop the ecu has enough lattitude to adjust.

bob

bob

Thanks for all your replies, think i will fit it just before the remap then and keep standard FSE. I did not know there was a 190l/h variant of the walbro, just went ahead and bought the one on performance subarus site so guess ive got the 255? Is there a way of visually checking the pump to see which version it is?

Check the code on the pump, GSS342 or 341 are both 255l/h HP.
JIM

Bob do you know how much difference a Walbro 190l/h pump will do - compared with the factory one - regarding fuel consumption etc?
My car is WRX03 PPP full decated and in some areas has more than 100% IDC which lead me to the uprated fuel pump (just for safety before the remap), 243BHP-248LbFt ATW with the above!
I'll add soonly an STI TMIC and AVO turbo inlet hose so the volumetric efficiency will increase ramarkably to accommodate the extra fuel supply!
Thanks in advance.
JIM

Just to bring the part no's up to date Walbro 190 high pressure pump with fitting kit for newage f20000141-400-791. Obviously will fit classic with cutting/soldering of wiring connection. £88+£15p&p+vat!!!!!!! Anyone seen it cheaper?
http://shop.edoperformance.co.uk/wal...it-p-9389.html
FYI itp159 classic standard fuel pump 165 lph
http://www.camskill.co.uk/m10b0s2606...rsions_1_to_6_

Thought I'd bring this topic up rather than creating a new thread but I've just had a Walbro 255l fitted to my 2003 WRX today ready for a remap and all the pops and bangs I used to get on the over-run or gearing down have gone. I thought over-fueling would create more pops?