I am having my fuel injector duty cycle and A/F ratio on the border line of safe and am wondering what the easy fix would be. I dont really plan on any more power modifications any time soon so I am looking to fix this in one step and not to be ready for future mods. I currently am running:
downpipe
catback
m2 intake
m2 ecu
ARC stock sized intercooler
boost set at 12 psi

with just these mods I do not think that I should be running out of fuel yet but there it is. Could my fuel pump be getting worn out? Should I just replace it with a walbro? If I do will I need an FPR to compensate for extra flow? I also own a PFS PCM that I could piggyback onto the M@ to adjust for the pump ( that is what I do to datalog). SHould I just figure it to be dirty injectors and send them to be cleaned? I know that that is a good Idea anyway but I have a hard time if the car has substantial downtime. I use fuel injector cleaner regularly also. the car has 73,000 on the odometer.
The problem has actually seemed to get worse lately. I havent changed anything recently but the A/F ratio seems to still be rising. Is this a clear indicator of anything? I understand that my method of checking is less than scientific, and people will say I need to use a wideband, but I make do with what is available and use the stock 02 sensoroutput. (which is only 5000 miles old if that)
Anyways, sorry for the ramble and thanks.
-steve young

 

Steve,

The simple fix would be to limit boost to 11 psi. This would keep you at a safer level.

If everything were running properly, you should be able to boost to 13 psi with no problems. I have similar mods as you, and have no problems. Are you hitting fuel cut? Why do you think you are running out of fuel?

 

Perhaps hot wire the pump to the battery. Use a 30 amp relay. This will ensure that the pump is seeing the highest voltage possible in the system at all times.

 

This may be a dumb question, but could your fuel filter be clogged? When did you last change it?

 

not a dumb question, but it was changed about 4000 miles ago.

 

I am seeing exactly the same problem. I have a PFC now and running the fuel map at max values while seeing injector duties in the mid to high 90s at 12 psi boost just to get to 11.2 AFR on my wideband at 8K RPM.

I've ordered a Walbro 341 pump and a Fuel Press. Reg. The correct solution would be to update to a larger secondary injector but, I am hoping that I can do the easy solution by putting in the larger pump and increasing the pressure for more fuel delivery. I will try to put the FPR into the fuel pressure return line so, I will not have to remove the UIM and the stock FPR this way. I have a few links here that I am looking at and they seem to show that probably just the fuel pump alone might fix my problem. I'll attach those links, hopefully you'll find it useful. Unfortunately I will not be able to install all these for a while due to an injury that keeps me pretty much inactive for a few more weeks.

To me the combinations of the fuel delivery curves for OEM pump and fuel requirements per maxcooper's calculator showns that the OEM pump may not be sufficient to supply the moderate amounts of fuel necessary for the given mods.

http://www.rceng.com/technical.htm
http://maxcooper.com/rx7/how-to/fuel_system/calcs.html
http://www.vfaq.com/pump-Walbros.html

 

Thanks axr6!
That is exactly the response I was hoping for. Thanks forthe links!
-steve