Fuel pump upgrades

[logic]

I'm looking at fuel pumps, and I'm seeing roughly the same pricing for the Walbro 190LP, 255LP, and 255HP pumps, which makes me wonder why I'd ever bother installing anything other than a 255HP.

I'm sure there's a good reason, presumably something to do with additional modifications that would need to be made to accomodate the higher-flow pump. Could someone elaborate a bit as to why you wouldn't just go with the high pressure pump right away?

(I'm in that camp of people who likes to do something once, and only once, if at all humanly possible. )

 

[RocketDSM]

Here's my take on it: Look at what the (lame) Honda guys are using for injectors...anywhere from 230-330 for stock. To them a "big" injector is a 400-450. We start at 450. We have problems getting too rich using a 255 pump without something to lean out the mix somewhere (agreed most of us have lots of extra airflow to cure this ailment). What happens when poor little Civic DX ricer boy drops a 255 pump on his 330 injectors? He richens to the point of flooding. The other pumps, although compatible with ours, are not meant for our cars, I THINK. Remember this is all opinion and what I've been able to conclude. But that is my .02.

 

[NDgsx]

190lph pump will be fine with the stock fuel pressure regulator.

255lph and larger flows too much fuel. The small opening on the stock fpr can not let it through. This ends up raising the fuel pressure. Normally your fuel pressure is supposed to go up 1psi for each pound of manifold boost and down 1psi for each in hg of vacuum in the intake manifold. Before at 0psi manifold pressure your fuel pressure would be 43psi, with the 255lph pump it will be around 55psi. It will not change from 55psi until boost goes over 15psi. The ecu does not have any clue about the new non linear fuel pressure curve and gets confused to all hell.

So in short yes you have to buy more . Charged air makes a adjustable fpr that bolts up to the stock fuel rail. There 1G unit is out, I am not sure on the 2g. Spoolinup also sells them.

I recomend the stock MKIV supra pump. It's a much higher quality denso unit, flows 260lph, and is nice and quite. Conicelli has them for the best price.

BTW the stock pump only flows about 100lph.

 

[roshique]

I am running the Supra pump, I also did the hard wire mod when installing it. Works great, no regrets. I have ordered many parts from Conicelli, prices can't be beat.

 

[Boosted97GS-T]

go buy a 3000gt vr4 fuel pump i think its like a 180lph or so. thats what i go and its quiet and gives enough fuel

 

[steve]

The VR4 pump is 180-190lph and a drop in replacement at least on my '91 GSX. It doesn't overrun the FPR and I'm seeing 1400 degrees on my EGT at WOT with my B16G at 10psi. I can't say what the injector duty cycle is until I get a logger but it looks like I have some room to work with before maxing out my stock injectors.

The Supra pump is also a direct replacement but it's alot more that the $35 I payed for a used VR4 pump.

Steve