Change that fuel pump!
Oct 25, 2003, 08:15 AM
#16
You can not use the HP version with the stock FPR, it will overrun it. If the low pressure version has plenty of volume (and thus can maintain pressure) for 400 hp cars up to higher than 8000 with stock fpr, can you explain why you are saying to go with a high pressure unit that dictates a new fpr? My understanding of the two versions is that one can attain a higher pressure, but both are rated the same in terms of volumetric output.
Originally posted by MP5
Well I never fully looked into it between the HP and regular Walboro units but the way I understand how the FFPR works is based off the manafold pressure so I think it is definately worth it to get the HF walboro that way you can sustain more flow at higher RPM and boost pressures without worry of instantly running lean- Remember the EVO is capable of spinning 7600 RPM stock thats gettin into severe duty if you are running good boost to redline.
Also the Supra pump has been discussed on every forum for some reason people thing a oem pump costing 2.5X the price of a walboro is better quality- Well maybe but it sure cant flow as much as the WB HP- it tanks out hard when trying to flow high pressure at high RPM/Boost- I know 2 guys that ditched the supra pump on the WRX in favor of the "crappier" walboro
Well I never fully looked into it between the HP and regular Walboro units but the way I understand how the FFPR works is based off the manafold pressure so I think it is definately worth it to get the HF walboro that way you can sustain more flow at higher RPM and boost pressures without worry of instantly running lean- Remember the EVO is capable of spinning 7600 RPM stock thats gettin into severe duty if you are running good boost to redline.
Also the Supra pump has been discussed on every forum for some reason people thing a oem pump costing 2.5X the price of a walboro is better quality- Well maybe but it sure cant flow as much as the WB HP- it tanks out hard when trying to flow high pressure at high RPM/Boost- I know 2 guys that ditched the supra pump on the WRX in favor of the "crappier" walboro
Last edited by Hammerli; Oct 25, 2003 at 08:21 AM.
Oct 25, 2003, 08:21 AM
#17
Originally posted by SILVER SURFER
The fuel pump replacement is not bad (15-20min), they could have made the opening a little bigger though, wrangling that fuel pump assembly with the retaining ring through the opening is a little tricky, and it's all plastic so you need to be careful.
It looks like the fuel filter is built into the entire fuel pump assembly, what's up with that? Anyone price that sucker yet?
I can tell you one thing, your not going to find it at the local auto parts store. I have 18K on my car so I should replace it pretty soon.
The fuel pump replacement is not bad (15-20min), they could have made the opening a little bigger though, wrangling that fuel pump assembly with the retaining ring through the opening is a little tricky, and it's all plastic so you need to be careful.
It looks like the fuel filter is built into the entire fuel pump assembly, what's up with that? Anyone price that sucker yet?
I can tell you one thing, your not going to find it at the local auto parts store. I have 18K on my car so I should replace it pretty soon.
Oct 25, 2003, 08:38 AM
#18
So are you guys saying that I can install the "low pressure" Walbro without the NEED for an adjustable FPR? Who has experience with this? I've got both the pumps hanging on my wall in the garage, but have not tried either do to not having a way to "tune them down" if needed.
PS some one had posted a "kit" was for sale, a while back, to make the standard Walbro 342 fit the Evo (couple of hoses and a connector). Anyone know who was selling it?
PS some one had posted a "kit" was for sale, a while back, to make the standard Walbro 342 fit the Evo (couple of hoses and a connector). Anyone know who was selling it?
Oct 25, 2003, 08:43 AM
#19
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If I don't plan to go much over 300whp (if I even make it to 300) should I even bother with this?
I have not measured my fuel pressure but I know that others (like Big Al) reported that the pressure starts to drop in the higher RPM's, I believe even in a totally stock car?
With the new pump I had to lean out the mixture in the high RPMS which told me the pressure was obviously dropping.
I don't know if I was seeing uneven cylinder fuel dispersal because of the pressure drop, or if the lower pressure/high injector duty cycle was causing poor fuel atomization, but either way there was a definiate problem there, and the fuel pump corrected it. This is at levels achieved by exhaust and turning the boost up (less than 300WHP), so....
Oct 25, 2003, 09:03 AM
#21
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Walbro makes pumps for OEM for many cars(Ford,etc..)so reliability is just as good as stock. Fuel pressure should remain at stock levels since this is a higher flowing pump (more volume per minute/hour) not a higher pressure pump. The filter you spoke about comes on just about every fuel pump out there. Its like a strainer more than a filter. It will catch only the bigger particles, smaller ones are left for the fuel liter. All pump-in-tank set-ups have this strainer attached,its not meant to be serviced.
When you need to replace the fuel filter you have to replace that entire assembly! The fuel level sender and all that stuff are designed to pop off and reinstalled on the new fuel pump/filter assembly. I have never seen anything like this before.
Oct 25, 2003, 09:26 AM
#22
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As far as injectors, don't you have to tell the ECU that there are larger injectors?
How could someone without a stand-alone EMS swap injectors?
Excuse my ignorance on the issue...
How could someone without a stand-alone EMS swap injectors?
Excuse my ignorance on the issue...
Oct 25, 2003, 09:32 AM
#23
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As far as injectors, don't you have to tell the ECU that there are larger injectors?
How could someone without a stand-alone EMS swap injectors?
How could someone without a stand-alone EMS swap injectors?
Oct 25, 2003, 09:49 AM
#24
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Originally posted by SILVER SURFER
Without some sort of fuel control, you really can't. If your running exhaust, higher boost, etc, I would recommend the fuel pump upgrade.
Without some sort of fuel control, you really can't. If your running exhaust, higher boost, etc, I would recommend the fuel pump upgrade.
Does the SAFC offer the ability to compensate for larger injectors?
Oct 25, 2003, 09:55 AM
#25
Originally posted by MrBonus
That's pretty much what I figured.
Does the SAFC offer the ability to compensate for larger injectors?
That's pretty much what I figured.
Does the SAFC offer the ability to compensate for larger injectors?
Oct 25, 2003, 09:58 AM
#26
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Originally posted by Hammerli
Indirectly, yes. Since you are adjusting fuel with the SAFC, you can dial in less fuel to trick the ECU to sending less voltage to bigger injectors for the same fuel at a given load.
Indirectly, yes. Since you are adjusting fuel with the SAFC, you can dial in less fuel to trick the ECU to sending less voltage to bigger injectors for the same fuel at a given load.
Oct 25, 2003, 06:33 PM
#27
I looked all over the place for the fuel filter but the only place that made sense from the shop manual was in fact what you found!
I agree very strange!
I agree very strange!
Originally posted by SILVER SURFER
No man, you don't get it, I am not talking about the little sock on the end of the fuel pump. The assembly that the pump actually mounts to, and the fuel lines connect too comming out of the fuel tank, that is the fuel filter! There is no seperate in-line fuel filter!
When you need to replace the fuel filter you have to replace that entire assembly! The fuel level sender and all that stuff are designed to pop off and reinstalled on the new fuel pump/filter assembly. I have never seen anything like this before.
No man, you don't get it, I am not talking about the little sock on the end of the fuel pump. The assembly that the pump actually mounts to, and the fuel lines connect too comming out of the fuel tank, that is the fuel filter! There is no seperate in-line fuel filter!
When you need to replace the fuel filter you have to replace that entire assembly! The fuel level sender and all that stuff are designed to pop off and reinstalled on the new fuel pump/filter assembly. I have never seen anything like this before.
Oct 25, 2003, 07:42 PM
#28
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I know this is the fuel filter, certainly makes significantly increasing the fuel supply more interesting. I am still wondering how much there going to want for that sucker. 
Oct 25, 2003, 10:22 PM
#30
As usual Silver Surfer, nice technical post.
I was just on the Dyno today and experienced detonation at 5000 RPMs that caused a dip in the graph. Naturally, the detonation was tuned out by the dip still exists. From Al's experience this is related to ****ty gas. I'd be interested to see how the fuel pump would affect the dip though. It is not noticable at all, just shows up on the dyno.
I was just on the Dyno today and experienced detonation at 5000 RPMs that caused a dip in the graph. Naturally, the detonation was tuned out by the dip still exists. From Al's experience this is related to ****ty gas. I'd be interested to see how the fuel pump would affect the dip though. It is not noticable at all, just shows up on the dyno.