walbro 255 in my s4 questions...
 

i recently installed a new walbro 255 fuel pump (+ new fuel filter) in my 88 na s4. the few mods i have are a hollow cat single exhaust and an air filter upgrade.

the only reason i went with a walbro over a stock pump is that the walbro was 1/3 the cost for a new pump. ($99 aint too shabby, compared to the mazda cost of over $350 for stock).

anyways, the car runs frickin awesome (and starts way smoother now too), but i can actually hear the fuel pump at idle. i couldn't hear the stock one at all. is this normal for these pumps?

i realize this pump is probably overkill (and maybe running a little rich) for my car... should i look into an adjustable fuel pressure regulator, or is there already something like that on the car? will my fuel consumption suffer by having this thing in?

after cleaning out the injectors, cleaning all grounds, replacing one completely seized 6PI actuator, new plugs, fuel filter and pump the car runs better than it has in the 10 years i've had it. it pulls smooth all the way to red line. i just don't want to fuk it up with this new pump... i know 10 years and i'm still a nub ;)

cheers.

they don't call 'em whinebro for nothin

just watch out, there was a thread about knock off walbro fuel pump. The whining is normal

Get a T2 stock 2ndary fuel rail and fpr, or, remove the stock one on the na, put in a 3/8" NPT tap and a barb fitting adapter and run it to an aftermarket fpr.

thanks for the replies folks.

well as far as i can tell there is no change in the way the engine is operating. in fact it's running better (smoother) than before.

do i really need to mess with the FPR? i mean wouldn't all excess fuel just go back to the tank? the injectors can only push through a certain amount of fuel at any given time anyways... the way i see it, there is just more fuel ready to be used, but it doesn't necessarily get used based on the current n/a FPR and limits of the injectors. i dunno, maybe i'm way off but that makes sense to me...

the FPR isn't necessary but you have to realize that due to the increased flow, that you will run rich and running rich causes power loss. You are right, the fuel does return to the tank but with no aftermarket FPR, the resulting increased flow creates increased heat and hot fuel isn't good either. Neither of these things are going to be catastrophic, just food for thought. I just went through the FPR debate and decided for now to just keep it simple.

FPR is a good idea, back when I was N/A i used a walbro 255 and the results were that it didnt pull nearly as hard in higher rpms cuz it was so rich due to the walbro overwhelming the stock FPR.
I used an SAFC to pull alot of fuel out.

your fuel pressure is too high, youre injecting too much fuel.

bah i think i'll just take the hit on this one and buy a stock after market pump for $30-50... which i should have done in the first place. i really don't want to mess with something that works, especially when it's 22 years old.

thanks again for all the help everyone!

anyone want a BARELY used walbro, dirt cheap? ha.