Does anybody know the flow rate of the fuel pump that comes in an 87 - 92 Supra. My buddy gave me his and I installed it. It seems to work fine (except it doesn't prime the line when the key is first turned on). My check engine light came on when I had the boost up(spikes to 18-20 lbs. oops). The code came up as "fuel trim malfunction". I can disconnect the battery and it goes away for a while then it will come back on later under any conditon (full or part throttle). The reason I'm asking about the pump is because my a/f gauge is reading dangerously lean at WOT and around 5000rpm +. I have no boost controller in right now and the adjustable set screw on the mas air flow is turned all of the way in to limit the amount of air through the sensor. My car is a 2g with stock t25. This turbo makes very little boost at high revs so I can't understand why it is running lean. I took the plugs out and they are not too bad but are white nontheless. I also get really crappy fuel mileage. I have been trying to nurse it when I drive it but having a bit of power on tap, this is easier said than done (as you all know). Lately I have been getting about 250 to (if I'm lucky) 300 kms to 50 litres. Is there something I'm missing or anything I haven't thought of. Please help. I don't want it to grenade on me!!

Mark, turbo supra or non? In either your stock pump would out-flow it IMHO.

MKIV Supra pumps are much larger, and a common upgrade for MK3 Supra's, 86-91 Rx-7's, Celica Turbo's, ect.

Take it easy on the car, keep the boost down, white plugs are *BAD* news...i'd go back to the stock pump, or if your intending to muck with the car just pick up a Walbro pump. At sub u100$ it's a wise investment.

Paul

"Fuel trim malfunction" probably means that the ECU is not able to adjust your closed-loop fuel delivery to get adequate fuel into the engine. It would normally do so by adjusting the injector duty cycle but in your case it has reached it's limit. This is unusual on a DSM and when coupled with lean A/F readings is a strong indication that you are not getting nearly the fuel you need.

When upgrading the fuel pump to a higher-flowing version it is also possible that the fuel pump overruns the stock fuel pressure regulator. In other words the regulator can't return the fuel to the tank fast enough. This can result in some funny tuning problems since the fuel pressure doesn't drop at idle like it should. I don't think this is the case here because of your plugs and A/F readings. Also, people who upgrade to Walbro 255 pumps don't normally report fuel trim errors from their ECU. It could explain your rotten fuel mileage but I suspect that is being caused by some other related circumstance.

If you didn't already rewire it when you installed it, you may want to try that. If the pump is not getting the power it needs to operate correctly it might not do very well.

Failing that, I think you should get rid of that pump ASAP and replace it with a known good unit.

Paul if you're talking about physical size of the pump, the stock pump was much smaller compared to the supra III pump. I've seen pictures of the MKIV pump and they appeared to be the same size. I'll try the rewire, if that doesn't work I'll put the old pump back in.