Just curious, I know you have to upgrade the fuel pump when going SR, I want to know if the fuel pump will do any performance difference with just a stock KA? or would you have to upgrade the entire fuel system?
I was pretty sure the upgraded fuel pump was only due to the increased injector size of the SR (or KA if going KA-T), so I doubt it would make any difference, but Im not sure.
I have recently found out that running a 255lph Walbro on a KA can potentially overpower the regulator therefore causing the addition of too much fuel.
Interesting.
I currently have a KA24DE with a Walboro (and nothing done to the
motor - all stock)
Haven’t noticed anything other then the problem I am having which
started before the pump was even put in.
Tell us more…i’ve wanted to know this same thing for a while now. Did it happen to someone local?
I hooked up a fuel pressure gauge after hooking up my Walboro.
When I started the car and it was idling, I was getting about 42psi.
THe FSM states that if the vacuum line is connected to the FPR, the
presure is 34psi. If the vacuum line is removed, the rate is 43psi. This
is on the stock setup.
BTW, The gauge was hookd up just after the fuel filter.
I think your regulator was just clogged dude
I don’t think there are any ill effects to running higher fuel pressure.
Don’t the turbo guys do it (by disconnecting the FPR’s vacuum line) to run
higher pressure? :dunno:
turbo guys use fpr’s with boost reference, meaning that will go up as boost increases, u dont disconnect the manifold reference line because ur fuel pressure will stay static .
running a walbro will give u higher pressure will cause u to run a bit richer, but if u have an intake it will help power a bit
Assuming they don’t run an aftermarket adjustable FPR.
Assuming they don’t run an aftermarket adjustable FPR.[/quote]
Turbo guys need to have some type of fuel management…
Running higher fuel pressure without tuning will cause your car to go rich. This is obvious. Having a clogged FPR will raise the fuel pressure as not enough fuel can flow out the regulator causing the pressure to go up, causing the car to go rich. This would reduce performance, N/A or Turbo. Either way the car has obviously already been tuned for the non clogged fuel pressure, and adding anymore pressure (fuel) will be unneccessary and a waste.
Some people use FMUs which are basically big ass fucking fprs which is GAY which raise fuel pressure like 10psi for every 1psi of boost, so if you run 10psi boost you’re looking at 100psi + base pressure which is just absolutly ridiculous. Its used for ghetto rigged little turbo kits for hondas and the such. Shitty disgusting way to tune.
Stock SR fuel pressure regulators are 1:1 as in fuel pressure goes up 1psi for every 1psi of boost, and i’m not sure if the KA uses this fpr as well or if it does not go up by pressure at all, having a vaccum line I would think it does do something, and would guess its a 1:1 regulator as well.
You dont need to upgrade the FPR if you have a different type of fuel control, I personally wouldn’t run more than a 2:1 regulator because flowing a lot of fuel at 80+ psi is a fucking bitch, and the more pressure the more prone everything is to leaking and stuff its just scawy :oops:
Fair enough. But that’s probablly not the case for my stalling issue. I’m
running a bit more FP then normal but it’s not enough to cause my car
to go all anal and stall every now and then.
My plugs obviously show signs of running rich so yea.
yea dude but like i said if your fuel pump ground for exampel was frayed then it would have this intermittant problem - when the pumped worked your pump would work fine and you’d have fine pressure and the car would be fine, but when it screwed up it would die at idle. I had that exact problem with my MR2.
BUT that being said I’m not saying thats your problem, i dont think it is because it would happen while driving as well. You have no problems while driving ever?
Nope driving is fine. I know for a fact it’s not fuel related. It’s definitely
something vacuum or even electrical.
Okay… so you guys are now way off topic. Running a little rich won’t cause any problems. I am running very rich and my car still drives fine.
The walboro on a stock ka won’t break anything, all it will do is maybe make your car run a little richer.
:thumright:
Just to add here,
The reason alot of people mention that a walbro causes the car to run rich is because due to the volume of fuel it pushes the fpr can’t maintain its base pressure because it is being overpowered and this in turn causes higher fuel pressure which results in a richer condition.
Its a weird situation though because some people are affected by it while others are immune.
What if I get VTEC will that help?
I’ve been using a Walbro on a KA for a while (20,000km+) both SOHC and DOHC and noticed no such thing. It does make sence where your coming from but thats not how a FPR works.
Yes, an upgraded fuel pump can overdrive a FPR. All that extra fuel has to go somewhere. It doesn’t mean it will. I think some people are getting lost on G(L)PH vs PSI.
It’s been a while, but IIRC 240s regulators are downstream of the rail. The rail is pressurized to a point, and extra fuel just gets sent along the return. The poroblem is a regulator is not exactly a precision piece. They have tolerances.
And as for running rich not being bad … just wait.
Gas has a nasty habit of washing your cylinder walls clean of oil. Raw fuel is slightly thinner than oil 
That’s REALLY rich though.
The stock KA pump isn’t really up to the task of the fuel demands of the SR. Just like the 300zx runs a bigger pump for the VG. They run at similar pressures, they are just able to flow more fuel @ that pressure. The harder a pump has to work, the faster it burns out.
If your stock pump is dying, it’s probably cheaper to get a Walbro (nissan wants like $300 for a stocker). But they are noisy, and they don’t last very long. Most cars will respond to a bit more fuel pressure if they’ve got an exhaust and an intake. Putting on an intake can lean out your motor a bit.