what fuel pump to run and where to get it?

[newbissan-tech]

ok so im looking into getting a new fuel pump and i looked on ebay and found walbro and some other company called TRE, im looking at getting the 255 lph but just wanted to get everyones opinion and also see if anyone could recommend where to purchase? thought there might be a sponsor on here or something! lmk thanks

[Carl H]

oem q45, outflows the waaaaahhhhbaaallllhhrrorooo 255 and is super reliable...unlike the walbro which i've replaced and seen fail/seize.relatively quiet too.walbro pump will ALSO require an adjustable fuel pressure regulator as it runs about 10psi higher nominal to the stocker.else bosch 040 or the bosch 044...accept no substitutes.

[Steve Lloyd]

If you are going in tank, I have a good Q45 pump that's in the Q45 that I bought to yank the motor out of. I'm doing a fuel cell so it will do me no good.........

I have a Q45 pump in my sr'd S13 and it flows great, it's just loud!!!!!!

[newbissan-tech]

thanks guys i just purchased a walbro and then turned around and cancelled the order! steve give me some info on this pump that you've got, condition of the car, miles etc. thanks again!

[Steve Lloyd]

Car had 92,000 on it, it's a 1994, the transmission went out. Car fired up and ran like a champ, just wouldn't go anywhere. Shoot me an e-mail and we can work out the details.

slloyd70 AT gmail.com

[Chrispy300]

walbro pump will ALSO require an adjustable fuel pressure regulator as it runs about 10psi higher nominal to the stocker.

First I've ever heard of this. What's the point of having a FPR if it can't cope with a different inlet pressure. The pump curve on fuel pumps isn't flat. I never had any trouble on my VG.

[Carl H]

its quite common actually, the walbro runs at a higher pressure and overruns the stock fpr...every car that i have seen fitted with a walbro has done this.

[newbissan-tech]

and now the debate is on! im liking the look of the vh pump but not sure about going used! and the walbro is new but don't want to deal with super rich conditions! nissans already run hella rich from the get go!

[Steve Lloyd]

Well, a new Q45 pump is over $200 and a walbro is around $100.

My used Q45 pump will be much less than both.

[gs14racer]

its quite common actually, the walbro runs at a higher pressure and overruns the stock fpr...every car that i have seen fitted with a walbro has done this.

yes this happens, it happened on both my ka and sr. However the vh it apparently doesnt (or at least for me) happen, i got a gauge right at the rail and fuel pressure readings where spec.

[LEMHEAD16]

I kept the S13 pump and have had no problems so far.

[Carl H]

^ lol thats death man!the stock s13 pump can barely feed its stock ka much less an sr or hardly an rb series...you really need to change that.

[LEMHEAD16]

yeah I know. It's on order. Should be here tomorrow

[newbissan-tech]

wow i'll make my decision tonight and go from there thanks for all of the input guys!

[T45]

The TT Z32 and Q45 FP are the same, FWIW, IIRC.

[XJared]

The walbro is actually a pretty good pump if you get a legit walbro and not a chinese knock off.

[Wes M]

What does the stock q45 pump flow and at what pressure? I've got a redline weber which will do a bit over 300lph at 50psi

[newbissan-tech]

good question anybody have a clue?

[Q45tech]

Everything you want to know:http://www.stealth316.com/2-fuelpumpguide.htm

[mtcookson]

Walbro vs. Q45/Z32 TT





Sorry for the bad quality on this one. Walbro outlet:



Q45/Z32 TT:

[Wes M]

Everything you want to know:http://www.stealth316.com/2-fuelpumpguide.htm

Nice one.. that's a good read

[SuperHatch]

yes this happens, it happened on both my ka and sr. However the vh it apparently doesnt (or at least for me) happen, i got a gauge right at the rail and fuel pressure readings where spec.

Thank You!

The Walbro's high pressure output has nothing to do with the increased fuel pressure in the few cars that experience problems.

Pressure is a resistance to flow, and it is regulated by the fuel pressure regulator. The Walbro FLOWS more fuel at a higher volumetric flow rate than most OEM pumps. The OEM FPR's cannot allow the excess fuel to return to the tank at a high enough rat, causing increased pressure.

Observed on a rail mounted fuel pressure sender on dyno and datalogged on streets, most cars that have insufficient FPR flow are 4-cylinder cars, and the issue rears its ugly head at idle and part throttle cruise. The IDCs are so low and there are so few injectors that the amount of fuel getting out of the rail is less than the walbro is feeding in, and the fuel pressure spikes causing rich conditions at cruise and part throttle. At higher RPM and higher loads, the IDCs get high enough that the fuel pressure returns to normal and the tune is still accurate.

Interestingly enough, some of the cars that do experience 2-3psi greater rail pressure still achieve stoich conditions at idle and cruise after the LTFTs reestablish themselves, and since the ECU ignores fuel trims at WOT, the tune, again, is uneffected.

Like Jerry said, on the VH this appears to be a non-issue since there are 8 injectors and the FPR dumping the excess flow at idle, and the Walbro has no problem keeping up at WOT.

[Carl H]

then why is it that us rb swap guys run silly rich when a walbro pump is fitted on an otherwise stock engine?

[gs14racer]

then why is it that us rb swap guys run silly rich when a walbro pump is fitted on an otherwise stock engine?

a dirty maf???

j/k i dont know

[SuperHatch]

then why is it that us rb swap guys run silly rich when a walbro pump is fitted on an otherwise stock engine?

Define "silly rich"...

Bone stock Evos with stock fuel pumps run in the 9.0-9.5:1 AFRs... I consider that silly rich, but its the stock tune.

Show me a stock RB car, with a new stock RB fuel pump versus a stock RB car with a walbro. If at 6000-8000RPM and WOT the walbro pump is richer than the RB pump I would be very, very surprised.

If you're telling me that a 150-200k mile stock KA pump swapped out for a walbro ends up in a rich condition, then I'd just tell you "no kidding" and laugh a bit.

Or, if you're telling me its richer at idle and part throttle cruise, then see my above answer. An RB barely moves more air than a KA, 2.0/2.5/2.6L versus 2.4? The volume of air consumed is so similar, the volume of fuel used will be similar too. Hence the overrun of the FPR.

[SuperHatch]

oem q45, outflows the waaaaahhhhbaaallllhhrrorooo 255 and is super reliable...unlike the walbro which i've replaced and seen fail/seize.relatively quiet too.walbro pump will ALSO require an adjustable fuel pressure regulator as it runs about 10psi higher nominal to the stocker.else bosch 040 or the bosch 044...accept no substitutes.

Also Carl, your Q45 argument would mean that your RB cars run even more stupidly right with a Q45 pump than a Walbro pump, are you seeing this too?

[Q45tech]

The proper way is to use an electronic fuel pressure sensor and examine the waveform of the fuel pressure. Remember the mechanical gauges average the pressure reported and at high flows it way get weird depending on the duty cycle of injectors. The oem rail was designed assuming a max duty cycle of 55%

[newbissan-tech]

GREAT INFO GUYS!!

[Steve Lloyd]

Your email went into my spam folder so I just saw it and replied

[EMK]

So if the Q45 pump outflows the Walbro GSS341 which I have been lead to believe in several cases than why do the tests show it the other way around? I was under the impression that the Q45 pump flowed near 304 lph and this doesn't appear to be the case at all.

Someone please explain this in a way a lowly engineering student can understand!