Hello<br /> First time user, sure hope you can Help. Have a 1998 Mercury 175 EFI been having problems with it for the past two years. On my most recent trip to Canada the engine ran poorly, very poorly. I always thought I had an electric problem since the engine would run well first thing in the morning when the outside air is cold, once engine gets to normal operating temperature it starts to miss and cough, I also will get a drop in RPM's. A friend had me check fuel pressure and I have 38 PSI during the initial 30 seconds the pumps starts and runs. Once the pump shuts down I lose pressure. First thought was that I was losing it through an injector, or that it was blowing pass a split o-ring so when I got home I removed the injector assembly from the motor. I found no leakage either in the injectors or o-rings. I found out the fuel is draining back into the pump. While I had the injectors open I preformed a spray test and found # 1 and # 2 injectors are not firing. Swapped wires and they will fire. Service manual states the problem is with the trigger, stator or inner switch box, which controls the firing of the injectors through the ECU. So the two questions I have are: are there any additions test I can perform in order to pin point the injector problem/switch box problem and why is the fuel draining back into the pump/bowl?<br /> Additional information:<br />* Checked fuel pressure while running 20 PSI.<br />* Checked fuel pressure with regulator disconnected 38 PSI with a good flow.<br />* Voltage to pump is in accordance with manual requirements.<br />* Rebuilt manual fuel pump last year.<br />* Fuel bulb is hard.<br />* I do have a blue spark to all cylinders, using the Mercury Spark Gap Tester.<br /><br />If you need any addition that may help please email.<br />Any and all suggestions you may have will be greatly appreciated.<br /><br />Thank you,<br /><br />Burstie