99GS400 VVTI engine running rich.... (Transplant)

[Spinnetti]

I transplanted this engine in a 90LS400 using the original fuel tank and pump and converted to return less using the GS in tank regulator. Its a race car, and I have dual exhaust, side exit and not cats but stock exhaust manifolds. Ever since, its been running rich. I put a fuel gauge on it and its right on 50PSI which I thought was about right? It starts and runs fine but of course my mileage is terrible. Is there anything obvious that would make the whole system run rich? I tried disconnecting the MAF and it wouldn't run at all, so I'm assuming that's not it. As a kludge in my last race, I just uncapped one of the vac ports and it was much better and stopped backfiring, but would be nice to figure this out. I have a generic code reader and it didn't read anything, probably because the car has a battery cut off - how long for codes to set?

Thanks!

 

[Zuffen]

Fuel pressure should be 42psi.

You may need to run a FPR and return line even though you have the in tank unit.

You can keep both as the pressure you want is lower than the in tank regulator setting.

 

[Spinnetti]

Thanks... I got a FPR and put it inline and kept the tank unit like you suggested (was more a PITA than I expected). I thought 42 was the magic number, but looking at the tech manuals I thought I read it was like 50? Regardless, I dialed it back as you mentioned since Toyota's have seemingly have always run 42 in my memory and its too rich at 50.

 

[gloverman]

Every time I have a vvti come in that has been converted to return style when running a stock ecu I repair it back to how toyota had it from the factory. The ECU is mapped for constant fuel pressure. If running aftermarket its not really an issue as I tune to suit. I often increase pressure to 4 bar without any over fuelling issues. Reading live data from the ecu is a basic first step for me.

 

[Spinnetti]

Every time I have a vvti come in that has been converted to return style when running a stock ecu I repair it back to how toyota had it from the factory. The ECU is mapped for constant fuel pressure. If running aftermarket its not really an issue as I tune to suit. I often increase pressure to 4 bar without any over fuelling issues. Reading live data from the ecu is a basic first step for me.

I don't have any tools to read data (is there a cheap consumer tool for that?), but if I understand you correctly your saying overfueling shouldn't be an issue? I'm using the GS fuel pump computer but the LS fuel pump.

 

[Spinnetti]

So car seems right now, but new by-product. Its always fired up instantly. After putting in the FPR, Sometimes its hard to start with a puff of smoke - could a leaky injector cause that?