It all started last weekend: After a trip to the beach I washed the ST(including engine) and put it in the garage. Next morning I drove to gym and the idle was surging, 200-1200rpm, it didn't won't to stay started, so I had to keep slight pressure on accelerator. Took it home unpluged and blew out the all the connections with compressed air(no help). Read codes, threw codes P0190 (Fuel rail pressure sensor Circuit malfunction), P0191 (Fuel rail pressure sensor Circuit failure), P2196 (O2 sensor rich, and P2198 (O2 sensor rich). Readout recommended replacing fuel filter, fuel rail pressure sensor, checking fuel pump for flow/pressure.
I decided to start with replacing fuel filter. So I pulled the ST into my workshop garage and shut off engine, raised hood and located fuel pump fuse(# 30) in junction box. Pulled fuse and marked location with red sharpie, and tried to start engine to relieve fuel pressure, engine would not start(I assumed it would start when I replaced fuse).
Replaced fuel filter and fuse, hooked up test hose and pressure gage to engine side of new filter and turned on ignition(gage regesterd 15psi), cranked engine and gage registered 82psi and osicilated there while I cranked engine. Gage held at 60psi until I unhooked it(indicating good fuel pump). To check flow, I took the gage off the end of my test hose and put in a gallon jug, and cranked engine(filled jug half full with a couple of cranks of engine) again indicating good fuel pump. Then I hooked the engine side fuel line to new filter and tried to start engine. Engine would not start. Cycled ignition on and off 5 times for 10 seconds each, and tried to start again(no start).
Located inertia switch and pushed it(no start).
Pulled a plug and checked for fire(good fire).
Checked compression(142psi). Replaced plug and tried to start(no start).
Replaced the Fuel Rail Pressure Sensor and tried to start(no start).
I cleaned the MAF with MAF cleaner(no start)
Cleaned and lubed the IAC but still no start
So I rechecked everything and verified that I had:
1. 80psi pressure to engine side of fuel filter
2. Good spark
3. 142 Psi of compression
The three things required for start but will not start.
The Check Engine Light goes off when cranking (indicating PCM is getting RPM signal)and the anti-theft light goes off when cranking
I think Pulling the #30 fuse initiated somthing that keeps the engine from starting but I can't figure out what(I replaced that fuse with new fuse just in case)
Will your fuel pressure gauge also work on the fuel rail? If so, check for fuel pressure there. You might try pulling a spark plug again to see if it is coated in fuel. Another interesting check, assuming the spark plugs are dry, would be to spray some throttle body cleaner in to the throttle body while someone else cranks the engine over to see if it will start this way. Just because you are getting fuel to the fuel rail does not necessarily mean the fuel injectors are activating and letting that fuel in to the cylinders.
Used starting fluid, but would not start, L1TECH off the My Sport Trac forum expressed the same logic as you, but he also stated, as a last resort, change the spark plugs, which I did, and the Trac started right up as usual.