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Old 11-18-2008, 03:55 PM   #1
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Default How much of this fuel issue do I need to fix?

See my sig for car info. I took the car to the dyno last month and it appeared that the stock fuel pump wasn't able to keep up with my fuel pressure needs. A couple weeks ago I upgraded to the Walbro 255. While a bit louder, I noticed a dramatic drop in fuel required to maintain my AFRs when autotuning with the Hydra. I had planned to go all out with the fuel system upgrade and get the M-tuned dual rail and connectors, and already bought the Aeromotive FPR with a nifty gauge and some tubing from the classifieds.

My question is, do I really need this? It appears most of my fueling issues have been fixed with the new fuel pump and from some posts here, the benefits of a dual feed rail when I have under 300rwhp seem limited. Right now I have about 250rwhp (according to the previous dyno tune) and would love to eventually get to the 300 level. In the group opinion, should I just keep the stock fuel rail and FPR, or ditch them? If I keep the stock stuff, I will probably get rid of the Aeromotive unit and recoup the cash for some other projects. Another option is to install the Aeromotive unit and to the DIY dual feed rail on my stock rail. Looking for some advice.
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Old 11-18-2008, 04:03 PM   #2
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the general consensus is: it takes 15 minutes to do a dual rail and it can't hurt.

I wouldnt worry about the FPR if you're not close to maxing out your injectors.
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Old 11-18-2008, 04:27 PM   #3
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I think: Your current OEM FPR is overloaded by the 255 Walbro. This is why you need to lower your VE table. I would not keep this situation.
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Old 11-18-2008, 04:30 PM   #4
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Quote:
Originally Posted by Spookyfish View Post
I think: Your current OEM FPR is overloaded by the 255 Walbro. This is why you need to lower your VE table. I would not keep this situation.
HE HAS A '99.



The 255HP fixed his very common "not-maintaining-fuel-pressure-in-high-rpms problem." With the fuel pressure being more constant in upper rpms, you don't need to hold open the injectors as long to provide to fuel.

... if it ain't broke.
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Old 11-18-2008, 04:41 PM   #5
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I would immediately replace fuel rail with a M-Tuned miataturbo.net for sale special.

=P
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Old 11-18-2008, 04:41 PM   #6
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Quote:
... if it ain't broke.
That is kind of what I was thinking. I think replacing my fuel pump fixed my problem, I am just trying to decide if replacing the rest of the system is worth the time / $$.

Of course, if all of us lived by the "if it ain't broke" mantra, this board wouldn't exist.
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Old 11-18-2008, 05:49 PM   #7
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IMO, yes, convert it to a return style setup and use your new stuff, except the fancy rail. It's not needed. I have added a return to my 99' in preparation for converting to a return style system. I have a Mallory 30-100PSI FPR w/ 1:1 boost reference I need to hook up one day. Figure I'll set base pressure around 70 PSI and run a 255HP. Should be good to go then.
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