Fuel pump circuit 2011 Tacoma

Does anyone know where I can find the circuit diagram for fuel pump. It appears my fuel pressure jumps up when towing, causing fuel to go full rich and blackening the fender around the exhaust. Tested all sensors, IAT, CTS, MAF, A/F ratios, Cat conv, plugs, air filter. MPG towing went from 13-14 to 8 MPG.

 

Here's a pointer to the Factory Service Manual for an '05 Tacoma. Lots of info there - you may already have it .

http://www.customtacos.com/tech.old/files/05FSM/repair.html

Just my 2 cents.

You mentioned increased fuel pressure. If I'm not mistaken, the fuel flow to the cyls. is provided by the fuel injectors. They provide fuel based on something known as pulse width - an electronic signal that lasts for a specific duration allowing the injector(s) to shoot fuel into the cyl. The PCM - power control module or main computer controls the signal to the injector. There may also be additional fuel pressure regulation in between the fuel pump and the injectors. My '15 Tacoma is new to me; I haven't studied the fuel system circuitry yet, so fuel pressure regulation may not include a regulator that was used on carb-equipped vehicles.

I'm not entirely sure that excessive fuel pressure would cause rich running in a fuel injected system.

 

I'd not think it's the pump /pressure. How much weight are you towing?? IT may just be that the engine is working harder with the excess load causing more fuel and RPM = more exhaust and poorer combustion/mileage ??? Check your ECU to see if you got any codes.