dmdicks
05-05-2004, 09:29 AM
Hey all!,
I bought a Walbro 255LPH EVO8 Pump and installed it into my BetaII Turbo Tiburon yesterday. Install was fairly easy but time consuming as I had to do a couple of trial fits to get it to work right. You see the new pump is about 1/4 inch longer than the old pump. I also had to use the filter screen that came with the pump instead of the Hyundai part. Other than that, its in and working.
Now here's what I'm seeing. The BetaII fuel systems have a Fuel Pressure regulator in the fuel pump assembly. This is a propietary item and cannot be upgraded. It's designed to push 49.5psi at idle with the ECU slightly increasing voltage to the pump at WOT. There is not a pressure switch anywhere in the fuel system that tells the ECU what is the current fuel pressure like I originally thought. Also the fuel pump connector is a standard two pin connector and it plugs right into the Walbro fuel pump.
So what happened when I installed it and started the car? My idle PSI is now at 80PSI due to the high volume pump overwhelming the OEM FPR. At first I was like "Oh crap!", but then I realized the car was running fine. Aparently the OEM ECU was able to cut the Injector pulse width down enough so even at 80PSI idle was unaffected.
So after that I decided to make some quick high boost runs around the block to see what happened (I know, I'm crazy like that). Guess what? Due to the high volume pump I run super mega rich at WOT!! This at 15PSI boost!!
I was at +10 on the SAFC with at 11.8:1 A/F Ratio before the install. After? All I know is according to my Wideband meter I was 'RICH'. Which means it was below 10.1:1!!! So I went down to -10 on the AFC and now am at a rock solid 10.5:1 ratio. I know its still rich, but I ran out of time yesterday. I plan on going to the track today for some more tuning.
Sorry for the long post but I felt this was news worthy..
I bought a Walbro 255LPH EVO8 Pump and installed it into my BetaII Turbo Tiburon yesterday. Install was fairly easy but time consuming as I had to do a couple of trial fits to get it to work right. You see the new pump is about 1/4 inch longer than the old pump. I also had to use the filter screen that came with the pump instead of the Hyundai part. Other than that, its in and working.
Now here's what I'm seeing. The BetaII fuel systems have a Fuel Pressure regulator in the fuel pump assembly. This is a propietary item and cannot be upgraded. It's designed to push 49.5psi at idle with the ECU slightly increasing voltage to the pump at WOT. There is not a pressure switch anywhere in the fuel system that tells the ECU what is the current fuel pressure like I originally thought. Also the fuel pump connector is a standard two pin connector and it plugs right into the Walbro fuel pump.
So what happened when I installed it and started the car? My idle PSI is now at 80PSI due to the high volume pump overwhelming the OEM FPR. At first I was like "Oh crap!", but then I realized the car was running fine. Aparently the OEM ECU was able to cut the Injector pulse width down enough so even at 80PSI idle was unaffected.
So after that I decided to make some quick high boost runs around the block to see what happened (I know, I'm crazy like that). Guess what? Due to the high volume pump I run super mega rich at WOT!! This at 15PSI boost!!
I was at +10 on the SAFC with at 11.8:1 A/F Ratio before the install. After? All I know is according to my Wideband meter I was 'RICH'. Which means it was below 10.1:1!!! So I went down to -10 on the AFC and now am at a rock solid 10.5:1 ratio. I know its still rich, but I ran out of time yesterday. I plan on going to the track today for some more tuning.
Sorry for the long post but I felt this was news worthy..