Are there 2 different kinds of Walbro 255LPH fuel pumps (S13b)…ie. high-pressure and regular pressure?
Hi-pressure is what you need, the low pressure one is for Carbed cars.
Reason I ask is I just bought (and received) a fuel pump and kit from Truboost:
https://www.truboost.com/catalog/product_info.php?cPath=26_28_67&products_id=113
and wanted to make positively sure it was the supposed “high pressure” model. Is it?
Thanks…
For anyone interested, I managed to answer my own question. There are indeed two different 255LPH Walbro pumps available for 89-94 240’s:
Part # GSS315-400-766 - Normal Pressure 255LPH
Part # GSS341-400-766 - High Pressure 255LPH
Fortunately, I have the latter as desired. This also may explain why some people using Walbros complain about running rich and others are fine.
the loopback system could be Slightly plugged, Remember, The injector’s dont use Everything that that Pump is tossing at them… a large presentage is being looped back to the tank ( kind of a wase IMO )
Also, before any of you Jump down my throat, i know the injector’s will regulate the Flow, but older ones and etc will not do the Job Due to wear, and if fuel is being Pelted at it. You can pick it up from here 
woo go 341 ! (I’ve got a bucket of these at work) althought the 342 seems to be more popular, prolly for civics and rice boxes
GSS250 190lph
GSS278 190lph
GSS315 255lph
GSS317 255lph
GSS341 255lph-HP
GSS342 255lph-HP