Coughing and stalling under load. No Codes

Yates65

Member
Aug 4, 2022
6
2
13
40
Utah
2003 GT 4.6 2V.
The car is bucking and stalling after it starts driving for a minute, but as soon as I push in the clutch it will idle fine. I can start driving again, but then it will start acting up again and usually die. After restarting once or twice trying to limp back home the fuel pump stopped priming in the on position before starting. 10 minutes later it will start priming again and will start and idle fine for a bit and then dies. Here are the test I have tried so far to diagnose the issue.

  • I replaced the fuel filter, but no change.
  • Using a fuel pressure test kit connected to the fuel rail I get 32-33 psi while pcm is showing 40 psi in my scanner. Removing the vacuum line to the FRPS the PSI on the rail moves up to 40. No fuel smell coming from the FRPS vacuum line, and the pressure never dips even just before it dies.
  • This is a returnless fuel system where the Fuel Pump Driver Module regulates the ground to the pump. I put a voltmeter to the + and - wires going to the pump. At idle it reads between 6-7 volts up to the point that it dies.
  • I put a noid light on each of the injectors and they all appear to be working fine. I did notice that just as the car would die during idle that the noid light would do one last pulse extra bright. Not sure if that is normal
 

Yates65

Member
Aug 4, 2022
6
2
13
40
Utah
Attempted another test tonight. I put a hose on the outward end of the fuel filter running into a fuel canister. I ran 12v directly to the pump and it flowed fine for a solid minute without any issue. I would say the fuel pump is probably just fine. Anyone have any thoughts?
 

Yates65

Member
Aug 4, 2022
6
2
13
40
Utah
Finally figured it out. One of the fusable links connected to the starter had a bad solder joint. I was playing with the wires in the engine bay with the key on and heard the fuel pump prime when I bumped one of them. I pulled out the wire and and sure enough the connection inside the loom was bad. I put in a better connection, through everything back together and it is working great again. 4 weeks of frustration thinking I had a fuel issue.
 
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