90 240sx fuel burning problem

[theboy419]

My 90 240sx(SOHC KA) has been having this problem of what seems to look like unburnt fuel coming out the back. My rear bumper is just black from it, and its not burning oil cause A) no blue smoke comes out while driving and B) the oil levels remain unchanged. I've been told it is likely the fuel pressure regulator sending too much fuel in, but was just curious if anyone else has any other ideas? Thanks

[rogoman]

Several things to check:1 - The coolant temperature sensor for the ECU may be bad2 - The O2 sensor may be bad3 - One or more fuel injectors may be leaking4 - Dirty air filter

[theboy419]

well, i just changed the air filter... a friend mentioned how to notice if the injectors seem to be leaking, cause it would likely smell stronger of fuel under the hood, which hasn't been noticed... but i suppose i can try the coolant temp and O2 sensors see where i go from there, thanks!

[theboy419]

i do have one more question... any idea where the coolant temp sensor is on the SOHC?

[rogoman]

There are two temperature sensors located on the front of the intake manifold near the top radiator hose. The larger sensor is for the ECU, while the smaller one is for the temp gauge.