01-03-13, 05:54 PM
About a 2 weeks ago my 05 STS 4.6L became hard to start. If the car sits over night it cranks up right away in cold or hot weather. However it takes at least 2 attempts for a hot engine start. The car will turn over several times and almost start but will not. If you stop and try - on the second attempt it will turn over a few times and then start up. After the car starts you can hear something running maybe a fuel pump and then it quiets down. If you let the car sit you will her this noise several times. The car has 96,200 miles on it. The battery is good. There are no security warnings. Then only change is I bought a new FOB which I programmed two days before this began the hard to start problem. I have also had several electrical issues, Nav system was replaced twice - which killed battery cell, all of the amplifiers have went bad at different times and been replaced. Any thoughts?
Wow! Two Nav's & all amps. Ever find a root cause?
Any trouble lights at all? Any codes set? Oil level good?
Check the intake manifold bolts but do not overtighten them.
Check the fuel pressure regulator...Starting issues during warm starts are a common sign of a bad FPR.
01-04-13, 11:31 AM
Curtc - I have a 2005 STS V8 which is experiencing intermittent hard starting. Meaning it turns over very well but does not crank until I get scared I am going to melt a battery cable or something. Then it will finally crank and run fine. I keep hearing about the FPR but I cannot find one on me Northstar engine. Where is it located? Would it be under the intake or behind the engine where it can't be seen? And the fuel pressure at idle is 69 psi with a gauge which checks out to be accurate. Isn't that extremely high? It drops to 60 psi when I turn the engine off.
01-04-13, 12:45 PM
Melting a battery cable is not something you should worry about. The issue with cranking forever without starting is related to overheating the starter and burning it out, draining the battery to the point it cannot crank anymore, perhaps fouling the plugs with fuel if you are having a spark or air issue.
I didn't think the STS would let the user crank the engine too long. 15 seconds is actually a long time for an engine to not start but shouldn't damage a starter. The OP stated it always started fine on the second attempt. If more persistent than that, I'd suspect a crank position sensor.