boost92Si

jfd: Let me put it this way... "Death to the Greddy box!!!". I spent/wasted too much time and money on this same problem 5 years ago and don't have any more patience for it.

To answer your questions, yes on the VAFC/check valve/FMU adjustment issues, and no on the ditching the FMU - it's there to up your fuel in response to increasing boost and you didn't mentioned any other way to do that. Just upping your injector size would only account for an across-the-board increase in air flow, like if you had some serious head porting/engine work or swapped in a B18. Also, your A/F guage going crazy is exactly what happened to me back in the day.

I don't think you wasted your money on an in-tank pump. I've been running one for ~5 yrs and have run as much as 10PSI with it (~8.5 regularly) and haven't had any problems (it's a stock D16Z, after all). You will need to check on the pump's ratings to see if it will support your horsepower goals. Some people want to run in-line pumps and don't check if their HP needs have some amazing fuel requirements (ie, don't build a fuel system for 500HP when your engine will only make half of that). A good in-tank pump will satisfy almost any D16 fuel needs you have for a relatively stock engine.

inspyral

boost92Si, are you running 8.5-10lbs of boost on stock injectors, a 12:1 FMU, and an intank pump? How is your intank pump able to put out enough pressure to support the FMU? Most of the "high-flow" intanks can only generate about 60-80psi MAX. Like I said above, they can flow high volumes, but cannot generate high pressures. Even if you set your static FP on the low side, let's say about 34psi, at 8.5lbs of boost, a 12:1 FMU is going to raise fuel pressure to 136psi(8.5 x 12 + 34), and I doubt your intank is going to be able to put out that much pressure. True, a decent intank pump, or even the stock intank pump is enough for any "near-stock" D16, but when you're dealing with an FMU, high pressure is needed, and intank pumps simply cannot generate enough pressure for an FMU setup(unless you're running low boost, like the GReddy kit in stock trim). Since an FMU relies heavily on fuel pressure, when you turn up the boost, you need more pressure. This is when an inline pump comes in. If you're running the GReddy kit in stock trim at 4.5lbs of boost, the pressure increase under boost with an FMU pretty much maxes out an intank pump(pressure-wise, not volume-wise). The GReddy box probably accounts for this by adding more duty cycle to the injectors to keep you from leaning out at that boost level, but it was only designed to work at 4.5lbs of boost. As I've cited before, DRAG and REVhard kits whose boost levels are between 7-9lbs include inline pumps to supply the 12:1 FMUs that come with them.

Sorry, I kinda rambled on there...
If you are not running a 12:1 FMU setup with just an intank pump, please disregard this post.

jfdmas

Dont think that I am stupid or anything but how do I adjust My static fuel pressure. The only thing that I have that is adjustable is the fmu. I thought that this is only used under boost. Am I wrong?? Please set me straight.

jfdmas

can I use any inline fuel pump or does it have to be a certain high pressure pump. Will any inline fuel pump create these pressures????

inspyral

I'm sorry, I thought you had an adjustable fuel pressure regulator. If you're just running the stock FPR, your static FP should not be anywhere near 60psi. Start the car and let it idle, then pull the vacuum line off your FPR and see what reading you get on your FP gauge. It should be between 30-40psi. That is your static FP. If your FP rises above that when you boost, then you know your FMU is working, but since it stops at around 60psi, then your intank pump can't put out enough pressure to raise it any further. Any inline pump should be fine. Like I said, try looking for a used Airtex pump out of a DRAG kit if you want a low-buck solution.

inspyral

Here's a Bosch one on eBay:
http://cgi.ebay.com/ebaymotors/ws/eB...tem=1852911637

boost92Si

inspyral: If you refer to my first post, you'll see that I'm running a piggy-back that controls fuel and timing relative to boost, a "missing link" (aka, a check valve assembly), and bigger injectors (I do run the 310's that I recommended). What you are saying about FMU's and stock injectors is true, and that adding ANY type of additional or replacement pump won't do that much to fix that situation (Yes, DRAG and REVhard can squeeze out maybe a couple of extra PSI intake, but they are also designed as intercooled systems along with the in-line pump). I'm kinda a d!ck about the whole FMU thing, as its only a band-aid for better forms of fuel tuning.

As far as the Greddy box goes, the only function I know that it performs is that its supposed to block an out-of-spec signal from the MAP sensor. That will give you a CEL if you get above around 3 PSI or so. Some newer piggy-back systems can use the stock MAP sensor up to around 1 BAR, but need a different MAP for higher boost. The only real fuel tuning I know of comes from the FMU itself, and that its rate is tuned to the volumetric amount of additional fuel that you can get from the injectors for a given increase in fuel pressure. The amount of fuel-flow increase, though, decreases rapidly as the momentary fuel pressure increases. I don't know of any function that the box performs that adjusts duty cycle itself - I don't think that it really does anything else.

jfd: If you haven't noticed, I'm down on the whole fuel regulator idea (recall my "Death" post). You shouldn't need to adjust your static fuel pressure unless you have increased your engine's nominal air demand or replaced it with a bigger engine (see my last post). Also, I'm not a big fan of the in-line pump idea: its more tubing, wiring, and work than running a high-flow/quality in-tank pump (insert KISS principle "here") along with competent fuel management (ECU or piggy-back). That's what I've done and been running that way for several years without any problems caused by this setup.

jfdmas

hey,
you guys have been alot of help. You have answered alot of questions that I couldn't get answered anywhere else.

Inspyral, I think I will be the winning bidder on that bosch fuel pump. Thanks alot.

boost92si Your set up sounds like it gives you all of the controll in the world. And I agree with the whole bandade and it being a quick fix, But the pocket says to go inline. When income tax returns come I will probably go piggy back because its what I wanted to do for a while now. I just never knew if it would solve my problem...

jfdmas

hey inspyral. You said that I would need to be able to create pressures up to 130psi in the rail under boost. Can I get a inline pump with the max of 80psi that would run in conjuction with the intank pump to create the pressure that I need or does it not work that way.

Do I need an inline pump that creates 130psi all by its self or can I go with a lower psi inline like a 80 that Will work with the intank.

I don't see how a 80psi and a 60psi(intank) would be able to create 130psi. But I could be wrong as proven before.??

inspyral

Most inline pumps should be able to raise fuel pressure past the 100+ psi range. My no-name inline worked fine with my stock intank pump, but some people actually remove the intank pump and replace it with a hard pipe and just run the inline. Bosch and Airtex pumps should have no problem reaching the presures you need. If you run an inline pump along with your intank, the intank would basically be flowing a lot of volume at lower pressures, and then the inline just pressurizes the rail.