CBR F4i Fuel Pump and Distribution Issues

[james17]

Im looking for some info and help on an F4i problem. Our engine ran perfectly on a stock intank pump but we have since converted to a mid 80's ranger pump (the one recommended on this forum) and have run into motor problems. The engine runs poorly, fouls the plugs, has lazy or nonexistant revving charecteristics and is smoking like it is rich.

We have a powercommander system piggybacked onto the ECU for tunning and have leaned out the engine by ( i believe ) shortining injector pulse width. Assuming that either volume or pressure is to high will shorting injector pulse widths fix this problem ? We are running the pump with no regulator or gauge, does the fuel pressure need to be regulated down when using this pump? Does anyone know what pressure and volume the stock F4i pump puts out? Could some other gremlin be present in our motor? Thank you for any help or suggestions.

[leclercjs]

Hi,

First advice, put to trash the PowerCommander. We ran it last year and found that it is very inconsistent and for tuning, you have not a lot of possibilities and range for fuel and timing. The best is to use the PE-ECU unit for an F4i. We had some problem at the beginning but my three engine guys we're telling me, their customer service is unbeatable and they have every answer to your questions or problems. And we are running the fuel pump that was recommended on this forum.

Hope it helps!!

[Charlie]

Holy cow, how are you running the pump without a regulator? Just plumbing it right into the fuel rail? No return line?

[Marc Jaxa-Rozen]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>We are running the pump with no regulator or gauge, does the fuel pressure need to be regulated down when using this pump? <HR></BLOCKQUOTE>

Yikes. You definitely need a regulator of some sort...we're using the stock manifold pressure-referenced F4i FPR with the same fuel pump.

Marc Jaxa-Rozen
École Nationale d'Aérotechnique

[james17]

Ok, about not running a regulator i mispoke. We are running the stock fuel rail and integrated regulator, what i meant to ask was do we need a regulator before the rail. We are running the stock fuel return line aswell. Should this system work as is?

To leclercjs, we had contemplated the possibility that it was the powercommander but dismissed that because of the new fuel pump. What is the tunning unit you name and who manufactures it?

Thank You to everyone again.

[Charlie]

James we had trouble over-running the stock F4I regulator. I suspect that is your problem. If the pump is supplying more volume than the regulator can return at the pressure it is set to, then your pressure will be way too high and vary with RPM (fuel used). It's a bad situation.

You need to get a gauge on your setup. It is a necessity on a car in my opinion. You can get 1/8 NPT gauges cheaply ($20), and you can drill and tap the end of a stock F4I rail to install the gauge (or just use an inline fitting before the rail).

The fuel pump has no effect on how the engine runs, unless the pressure is off. So find out what your pressure is and go from there. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Marc Jaxa-Rozen]

Based on our experience the Ranger pump/F4i FPR setup works well enough...the engine holds a steady 48-50 psi, which IIRC is the stock F4i pressure. I agree about the pressure gauge being a necessity, though.

By the way, the ECU JS mentioned is the Performance Electronics PE-1, http://www.pe-ltd.com/ . You can't beat it for a combination of price/features/support.

Marc Jaxa-Rozen
École Nationale d'Aérotechnique

[Charlie]

Marc, we are not using that fuel pump. However it might be worth looking into. If you are referenced to vacuum the idle fuel pressure might be supposed to be lower than 50 psi. In our case we saw about 60 at idle and ended up using a different regulator in 2003. In 2004 we used our own fuel rail.

[Daygo Nighthawk]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by james17:
Our engine ran perfectly on a stock intank pump but.. <HR></BLOCKQUOTE>

Problem #1

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by james17:
Could some other gremlin be present in our motor? <HR></BLOCKQUOTE>

Yes, a bunch of students who can't leave good-enough alone. http://fsae.com/groupee_common/emoticons/icon_wink.gif