wadzii

check out the fuel pump section at www.hondata.com are you sure you installed the black box correctly?? or does it jus plug in??? also.. try taking out that fmu.

boost92Si

jfd, I had one of the first Greddy kits for my 92Si and had similar problems. My fix was to go a little further that you did and get: an EFI Systems PMS piggyback computer, built my own "missing link", and bigger injectors (I recommend 310's). FYI, their "black box" is a "POS". Mine went out early and I was forced to do what I mentioned above.

Since you mentioned that you are running an adjustable (?) B-D FPR with the box, I'll recommend that you keep your fuel pressure static initially and just work around the box issue. From my experience/learnings, all the box does is block an out-of-spec signal from the stock MAP sensor to the stock ECU; some more modern piggyback/replacement ECU's can use the stock MAP sensor up to about 1BAR. You seem to have a B-D FPR, so I'd recommend you just block high-pressures from the intake manifold with a missing link or similar contraption, and just tune your fuel with the A/F guage and regulator adjustments.

I have a Walbro in-tank pump upgrade and agree with all the others that recommend pump upgrades (one in-tank upgrade is better than trying to juggle pressures and pressure-related responses of a couple of differently-rated pumps in series; all I have is the upgrade pump and the STOCK regulator).

Keep in mind that the Greddy engineers were only getting their kit to market to satisfy their own minimal expectations. I've heard of people getting ~10-12 PSI off of the Greddy kits regularly, but everything else associated with the kit (fuel, boost control, blah, yak, blah) should not be confused with stock in these cases.

You mention that you have a Holley-brand regulator vs. the unlabeled-but-still-Vortech-brand regulator that I originally got with my kit. I don't know what your current fuel rates are, but you might want to consider changing from a somewhat-blind FPR arrangement to an additional/adjustable injector system.

jfdmas

boost92si.
Are you saying that I can simply solve my problem by getting a vafc to control injector pulses. And just to use a check valve for my map sensor. And just monkey around with the fmu settings until I get the proper or close a/f readings. Or even just use 310 injectors and ditch the fmu all together.

So I probably should just ditch the greddy box.

Ian Gattie

I'm jfd's freind. Anyways, to out 124 psi's of fuel under full boost does not sound right to me, unless I'm just not understanding exactly what you are saying. That sounds like way to much due to the fact that we set it at 60 Psi in thew rail and the car ran like s****. The 124psi you are talking about is in the fuel rail right??

edit: ditch the greddy box!!!!!!!!!

jfdmas

Inspyral,

every thing that you are saying makes sense. My turbo does't spool in neutral so I took my hood off of my car and I made my buddy stick his head out the window to read how much the fuel pressure guage was reading. When ever I had the fuel at around 60 psi and my car started bucking and blowing black smoke out the tail. I was assuming that I was running to rich but my af guage was going crazy!!!

inspyral

60psi of static fuel pressure is a bit much, considering spec is 30-40. Again, static fuel pressure is with the vacuum hose OFF the regulator so that it sees atmospheric pressure. If you start with a given static FP, once you boost, your FP should be rising above that number if your boost dependent FMU is working right. The 124psi I was talking about was if you are running 40psi static FP, and had a 12:1 FMU on 7lbs of boost(7 x 12 + 40). Yes, this IS a high amount of fuel pressure under boost, but that is the drawback of FMU fuel setups. If you plan to run high boost, then you're generally prepared to invest in better ways of handling fuel, but for lower boost levels, an FMU setup is fine, which is why a lot of kits (DRAG, REVhard, GReddy, etc) include an FMU to add fuel for their kits, which are designed with lower boost levels in mind. Again, if you do not have an inline pump, you will never see these kind of fuel pressures since an intank pump cannot produce that much pressure.

So, either your FMU is not fuctioning properly, or your intank pump is not putting out enough pressure to allow it to do so. In either case, that would explain why you're fuel pressure is not going beyond 60psi or so. Try setting your static FP to around 40psi and make another run with your buddy hanging out the window(never thought I'd be telling someone to do that...) and see if your fuel pressure rises beyond 40psi under boost. If it does then you're FMU is fine, but your pump can't supply the pressure needed to raise the FP further, if it doesn't go past 40psi, then your FMU is not working properly. If it goes up to 45-47psi or so, then what you have is a 1:1 rising rate regulator(raises FP 1psi per every 1lb of boost), and not a boost dependent FMU.

You can run a check valve for the MAP and get 310s, and they should be able to idle on your stock ECM, but you'll probably be running pretty rich. If you did that, you could probably play with your static FP to get it to run pretty decent, without an FMU. Yes, you could get an AFC or other piggy back fuel controller to fine tune it, but it's not absolutely necessary.

Or, you could run check valves, keep your stock injectors, run a 12:1 FMU(or get your existing FMU to raise FP 12lbs per 1lb of boost), and an inline pump. This should also run a bit rich, but only under boost, since the FMU is only raising FP under boost. Oh, and your FP will also be pretty high under boost as I have explained. You can add a fuel controller to this setup as well, if you want to fine tune your fuel map under boost.

In either case, you would need to get rid of the GReddy box. If you choose to go with larger injectors, then your high-flow intank pump should be more than up to the task, but if you plan on using(or continuing to use) an FMU setup, an inline pump is crucial in order to provide the high fuel pressure an FMU needs.

jfdmas

thanks inspyral,

you explaining it on a kindergarden level helped me understand more about what you are talking about. I now know what I have to do and I have a few different options.

one more question.

Are the injectors that I am running going to function o.k. under such high pressures. Venom oem replacements, 10% over stock flow......

jfdmas

What kind of boost levels are the fmu's good for. Because after I get my stuff running right I plan on turning up the boost.

jfdmas

Inspyral,

what do you recommend for inline fuel pump. Iwant something that is sure to work since I already wasted my money on a intank.

inspyral

Your injectors should be fine, and unless you plan on running more than 10-12lbs of boost, an FMU setup is fine. If you want to boost more than that, it's time to think about better means of engine management and replacing some of the weaker stock components like pistons and rods. I personally would not run an FMU setup if you plan on boosting more than 10lbs, and I would not boost more than 10lbs MAX on stock D series internals, which means a max of 7-8lbs daily, and 10lbs at the track with race gas. There are plenty of good inline pumps available. Bosch comes to mind. Also, when people with DRAG kits and the like decide to upgrade their fuel system for more boost, they usually ditch the Airtex inline pump that comes with the kit and oyu can pick those up relatively cheaply. When I was running an FMU, I was running a no-name inline pump(I was told it was a Bosch, but it was unmarked) and it worked fine. If you run an inline pump, try not to mount it on the firewall or else you'll be hearing it at idle and it's kinda loud.