Another 03 Stalling

[Joe Lorenzo]

Hey guys, first time-long time



Picked up an '03 ST back in August, been in the process of tuning it up and have already replaced the fuel pump, fuel filter, PCV valve, IAC valve, and sparks & wires (Previous owner did zero preventative maintenance).



Current Situation: During a cold start, it starts up strong. About 5-10 seconds later, it sputters out. Feels like maybe it could be starved for fuel, but I'm not sure. No evident vacuum leaks either (I've inspected the notorious elbows). Ive got a multimeter and I've already shot a couple of wires (including the fuel shutoff switch), but I'm out of ideas and not afraid to load the parts cannon :banghead: :fire:



Thanks

 

[swshawaii]

Trouble codes? Check engine light (CEL) NOT always lit for DTC's stored in memory.

 

[Joe Lorenzo]

Sorry, no, Engine is not throwing any codes and no CEL illuminated.

Perhaps because I can't get it to stay running long enough? Not sure.

 

[swshawaii]

Did you REMOVE the PCV elbow to inspect the BOTTOM side? They've also been known to be bad without throwing a CEL or lean codes.



If it rips when removing, it was deteriorated, and probably toast anyway. Keep us posted and GL.

 

[Todd Z]

Fuel injectors? Pressure regulator? Ignition coil? Clean MAF? .



ALSO the MAF wiring insulation to the plug is known for rotting off as so is the Knock sensor. Check and make sure the wires are not rubbing or causing the issue to.



Todd Z

 

[Vic Sorlie]

If you think it's fuel starvation I'd check fuel pressure with a direct gauge. Even though you've changed the fuel filter it may be blocked. Throwing a new one on and cutting open the old one could tell you more.

 

[Joe Lorenzo]

*UPDATE*



With the holidays finally behind us, I was able to get back to work on the ST. Here's pretty much what happened:



- I accidentally got myself into a no-crank situation when I blew the ignition fuse :toilet: during troubleshooting (15A mini fuse, front left dashboard panel). Took awhile to figure that one out as it wasn't on the start/ignition schematic I was using.



- After that, I figured I'd checked the rest of my fuse/relays just to get the warm-n-fuzzy :driving: ; Power distribution checks good (as far as the Fuel/Start/Run circuits are concerned).



- Got it cranking again, so I threw a fuel pressure gauge on the fuel rail; no dice, gauge read 0 PSI. Ok, so I'm not getting pressure to the fuel rail, this IS a fuel starvation issue, but why? I disconnected the forward line on my fuel filter to see if I was getting ANY pressure from the pump; not a drop. :banghead:



So, unless I'm missing something, it seems like I've got a bad fuel pump on my hands (even though I JUST replaced it in October) or a connection issue at the pump; either way, I gotta drop the tank. What are the odds of that?



Am I missing anything? nline:

 

[Richard L]

I agree with most of the other suggestions. Be sure you check the PVC elbow connector...a commons source of vacuum leaks. I would also be sure that the IAC and throttle body are squeaky clean.



If you are not getting fuel pressure, check the fuel pump fuse, and check that the fuel safety cutoff switch has not been trigger to shut off fuel.



Early model Sport Tracs were notorious for having fuel pump leaks in the tank and loosing pressure....however the only way to tell if it is the fuel pump leaking pressure or not even pumping is to check the voltage at the fuel pump when the ignition is on. The fuel pump should run for about 10-15 seconds as soon as the key is turned on to build up pressure. If you are getting voltage but the pump is not running or not building enough pressure, then you probably have a bad fuel pump.



...Rich

 

[Joe Lorenzo]

welp, dropped the tank and changed fuel pump, again. works like a charm now. guess I bought a faulty pump the first time around. :boohoo::banghead::banana: