Help with tunning and fuel pump

[01TruBluGT]

I am trying to figure out what is the best route to take and am trying to figure out if my tune will be affected or if I will need to re-tune. My fuel pump took a dump, I was thinking of just replacing with the same stock pump but then I figured if I have it opened up I might as well go to a Focus SVT pump. All the looking around and tracking down part numbers I came to the conclusion that it is hard to really know if what I am buying is really an SVT Focus pump or something re-manufactured using the core of an SVT Focus pump. My car is N/A with minimal mods and tuned getting 330hp/334tq and I don't see any major mods on the horizon. I am thinking about getting the Aeromotive 325 Stealth to put into the car to get her up and running again. What I am trying to figure out here is if I upgrade to the 325 pump will I need a re-tune to keep from running rich? Is anything in the tune related to the size of the pump or will the pump just do what it has to do to supply my fuel rail with the pressure that it needs based on the adjustments made during the tune?

If I am going to need a re-tune I am just going to go back to the stock pump as there is noone in my area that does tunes anymore that I know of. I have been searching and some people say I will need a re-tune with a bigger pump, some say I won't. I just need a definitive answer so I can get the pump and get my Mach up and running again.

[Mach828]

Those 340 pumps tend to die. And it doesn't fit the hat, so you would need to mod it.

I think JMS has a 340 that is the same size as stock. You can also just get a Walbro 255.

The correct way is to get a retune with upgraded fuel pump tables. However, many tuner do not do this. It is able to learn the fuel pump flows. With your minimal mods I wouldn't worry about it.

[01TruBluGT]

Sounds like the 255 is the way to go then. So the ECU will realize that the new pump flows more and adjust on its own to keep me from running rich?

[01yellerCobra]

Will the 255 last in the returnless set up? The ECU does learn the needed voltage eventually. Thr voltage table is a starting point for when the battery is disconnected or the ECU is flashed.

[01TruBluGT]

I've been reading up on the 255 and I'm not sure it's made for returnless.

I'm thinking about just going with the Focus SVT pump, I can get that for right at $200 but a Motorcraft stock pump will run me a little over $400. If I could find the stock pump at a reasonable cost I would just do that and call it a day.

So yeller, your saying I may run rich for a while till the computer learns the new pump?

[DSG2003Mach1]

Doesn't the focus pumpnrequire some wiring upgrades as well?

[01yellerCobra]

Originally Posted by 01TruBluGT

I've been reading up on the 255 and I'm not sure it's made for returnless.

I'm thinking about just going with the Focus SVT pump, I can get that for right at $200 but a Motorcraft stock pump will run me a little over $400. If I could find the stock pump at a reasonable cost I would just do that and call it a day.

So yeller, your saying I may run rich for a while till the computer learns the new pump?

I doubt it'll be that far off. If you went with a 340 I'd say you might need adjustment in your tune.

Originally Posted by DSG2003Mach1

Doesn't the focus pumpnrequire some wiring upgrades as well?

I knew guys that dropped them in with no issues. Maybe it's different if you run two. I ran twin GT pumps on a stock FPDM with just a wire upgrade.

[DSG2003Mach1]

Ya you're right that's a dual pump thing

[TKat13]

when looking for aftermarket pumps, just make sure they support PWM, Pulse Width Modulation, that is what is needed for a returnless system. Way back in the day, when I put a 340lph pump in, I had to have the tune adjusted.

[01TruBluGT]

Originally Posted by TKat13

when looking for aftermarket pumps, just make sure they support PWM, Pulse Width Modulation, that is what is needed for a returnless system. Way back in the day, when I put a 340lph pump in, I had to have the tune adjusted.

I would imaging the SVT Focus pump supports PWM, are you saying you only need to adjust time if the pump DOES NOT support PWM??

[01yellerCobra]

Originally Posted by 01TruBluGT

I would imaging the SVT Focus pump supports PWM, are you saying you only need to adjust time if the pump DOES NOT support PWM??

No. If the pump doesn't support PWM it'll burn up. That's why I was asking if the Walbro 255 is compatible now. Way back when I first started playing with mod motors most companies still included the 255 in their blower kit. But the 255 would burn up because it's designed to work at 100% all the time.

FWIW I went from a stock single pump to twin Cobra pumps in my 01. I didn't adjust the tune and didn't have an issue. So I would think the Focus pump would be ok.

[TKat13]

Originally Posted by 01TruBluGT

I would imaging the SVT Focus pump supports PWM, are you saying you only need to adjust time if the pump DOES NOT support PWM??

The Focus pump supports PWM. and no, that is not what I am saying, your tune may need to be adjusted after a swap, just ask your tuner. I just remembered that when I put the 340lph in, I also had a boot-a-pump for the factory pump, I had to readjust everything because with both there was not enough adjustment range. I am sure a focus pump is fine.

BTW, I agree, the old 255s did not support PWM and I had a buddy go through three before we figured out why. Then it was painfully obvious.

I did a big write-up on this a few years ago here, I will see if I can find it.

[ab_mach1]

What about this fuel pump?

http://www.highflowfuel.com/i-239056...1998-2004.html