sherpamike
Active member
I've been chasing some surging issues for some time now and have gone down many rabbit holes to get to this point. For disclosure, I've checked for air leaks and vacuum leaks. Worked on my timing, IAC motor, and many ignition components. Along the way I've addressed some issues and the truck runs pretty well now but still has an intermittent hunting/surging idle problem and I continue to get codes 44 and 45 (sometimes together, sometimes not) for the lambda sensors.
Well I just checked the fuel pressure at the filter (removed the filter and swapped a schrader adapter). When the pump comes on I get 39-40 psi. That pressure drops relatively quickly. At 1 minute of hold time (engine off) it drops to 36 psi. At 2 minutes its 34 psi, 32 psi at 4 min, and 30 psi by 10 minutes. I assume this leak down isn't in spec, though I can't find reference to what is too much leak. What's next, fuel injectors? Do the pressure regulators on the fuel rail go bad? Anyone have any good/bad luck with the inexpensive 19 lb Ford injectors on Ebay? What about rebuilding current injectors? Really just looking for others' experiences here...
Also, when the I start the motor (3.9L stock V8) the fuel pressure seems to cycle between 32 and 36 psi in combination with my hunting/surging idle. I've got a decent video of this where you see the gauge and hear the motor's revs up and down. I am hopeful this is a cause and not a symptom. Any thoughts?
Well I just checked the fuel pressure at the filter (removed the filter and swapped a schrader adapter). When the pump comes on I get 39-40 psi. That pressure drops relatively quickly. At 1 minute of hold time (engine off) it drops to 36 psi. At 2 minutes its 34 psi, 32 psi at 4 min, and 30 psi by 10 minutes. I assume this leak down isn't in spec, though I can't find reference to what is too much leak. What's next, fuel injectors? Do the pressure regulators on the fuel rail go bad? Anyone have any good/bad luck with the inexpensive 19 lb Ford injectors on Ebay? What about rebuilding current injectors? Really just looking for others' experiences here...
Also, when the I start the motor (3.9L stock V8) the fuel pressure seems to cycle between 32 and 36 psi in combination with my hunting/surging idle. I've got a decent video of this where you see the gauge and hear the motor's revs up and down. I am hopeful this is a cause and not a symptom. Any thoughts?
