Low Fuel Pressure

Bought a fuel pressure test kit and tee'd it in at the first connection in the engine bay before the fuel rails. Runs at about 45psi at idle and bounces a couple psi when rev'd. While driving, hard acceleration or driving up steep incline, gauge shows fuel pressure dropping down to around 20psi while the engine is sluggish then erratically increases along with engine rpm until it seems to clear it's throat around 3k rpm when pressure gets in excess of 60psi. So far, I've replaced spark plugs, MAF sensor, the whole fuel pump assembly, pressure regulator on the end of the passenger side fuel rail, cleaned the throttle body and it's still having the same issue. What's next? The sluggish performance increases with outside air temperature. During the winter, the issue is barely noticeable. Above 90 outside, this thing hesitates soo much, I fear it's going to leave me stranded at times. Only codes it ever throws are for lean fuel mixture. Truck has TRD Supercharger on it since new. This issue started about 3 summers ago and seems to get worse every year.

 

Did you replace the whole fuel pump assembly with an OEM?

Just to he clear, you did not just replace the fuel pump and sock, correct?

Have you checked for vacuum leaks on and around the s/c?

 

No idea about the tacoma supercharger but I know many superchargers require a higher pressure/flow fuel pump and different fuel injectors for the increased gas required. Did you get a stock fuel pump or one matched for the supercharger?

 

Yes, replaced the whole assembly, not just the pump and sock. What's the easiest way to check for vacuum leaks?

 

Fuel pump and injectors are correct for the supercharger.

 

What condition are the wires going to the fuel pump resistor? The resistor has a large heat sink on it in front of the battery.

 

As a test he could jumper across the connector that plugs into the resistor. Pump will run on high speed all the time.

 

Are OEM fuel pumps even available for older Tacomas? Checked two websites and both claim not available at this time? For a '06.