2004 LS 3.9L Not Starting

[vvansant]

Hi,

I'm new to the forum, hoping someone can assist.

Wife was backing out of the driveway tonight when the engine died, no rough idle or dash malfunction lights just stopped. Now it won't start at all. I don't hear it cranking or turning over, just a humming sound when turning ignition switch. Battery is about 6-9 months old, cables and terminals are shiny and clean. The security light is not flashing, it doesn't start in neutral or park, and the fuel pump kill switch is not engaged, apparently all common issues. I can't imagine a bad fuel pump because I smell gas in the engine compartment after several start up attempts, and a defective ignition switch or starter wouldn't have killed the engine in the first place. Could it be battery or alternator? What about plugs or COPs? Any additional thoughts or suggestions are appreciated.

 

[don-ohio]

I had the neutral start switch( DTR switch) go bad on me, but it never killed the engine,just caused a no-start condition. don-ohio ^)

 

[vvansant]

Thanks Don. Like you said, shouldn't have killed the engine once it was running, plus I tried starting the engine in neutral which I believe bypasses the DTR switch, correct?

 

[don-ohio]

No, I don't think it bypasses it. Mine wouldn't start in neutral OR Park. But once it cranked and the engine ran, I never saw it kill it.It was an intermittent problem at first.
Could be a low voltage problem, or shorted alternator I guess. Check battery voltage and your terminals. The battery should show 12.5 to 13.5 volts while engine is off. don-ohio ^)

 

[1LoudLS]

what do you mean by you only hear a humming noise? like the super quiet fuel pump hum, or louder, like a starter (or just some parts) spinning and no grabbing anything?

 

[vvansant]

Definitely not the hum of the fuel pump, that's in the back...this is coming from the front, it's the sound I hear where I expect to hear a typical starter engage. It sounds like its trying to initialize something. Most cars click when the battery dies, but this is more of a hum, hard to explain because I've never heard this noise before, or at least never paid attention.

The noise I hear might simply be the starter trying to engage, not sure. Engine never tries to turn over though.

 

[joegr]

So, you are saying that the starter is not turning the crankshaft when you try to start it?

If so, then the odds are:
1. Failed alternator that allowed the battery to discharge too low. This would explain the engine stalling as well. You may need a new battery as well as a new alternator. Test by fully charging the battery. If the car now starts, then measure battery voltage while running. It should be about 14.2 volts. Less than 13.8V, and you have a charging system fault (probably the alternator).
2. Loose or corroded wiring.

 

[Driggy]

Sounds like starter is spinning but not engaging flywheel. Pull starter and have it tested

 

[joegr]

Sounds like starter is spinning but not engaging flywheel. Pull starter and have it tested

Well, it's possible that he had two different failures at the same time (starter solenoid failure would not cause engine stall), but it is seems more likely that a single problem is at the root of both issues. BTW, it's a flexplate in the case of an automatic, not a flywheel.

 

[vvansant]

Thanks for all the replies. So, called the motor club and got a free tow to my mechanic. Here's the weird part, started fine for them first time and every time since. Fuel pressure and charging systems tested good. I had been having occasional loss of power before all this happened, like I would punch the accelerator and it wouldn't grab right away, now that problem is gone too. I'm really starting to suspect a fuel pump on the fritz, but what made it start working again? I'd go ahead and replace it proactively but there are 2 pumps and I don't know which one is the suspect. Thoughts/suggestions?

 

[joegr]

Sometimes, the physical shocks from the car being moved can free up the pump enough that it runs again. I've hit the top of the tank with a hammer before to get one going. The passenger side pump is the electric one. It's unlikely to be the jet pump on the driver's side.

So, what was all that about the starter not working then? "I don't hear it cranking or turning over, just a humming sound when turning ignition switch." It's impossible to help diagnose without reasonable descriptions of what is going on.

 

[don-ohio]

If it did it before,it'll probably recur. You might not want to take it on a long trip for awhile,until you're sure the problem is gone. Have you run any codes on it? don-ohio ^)

 

[vvansant]

It wasn't trying to engage the crank shaft when I turned the key; it would make a sound like it wanted to engage but never turned over. I would think if the fuel pump was not sending gas the engine should still try to turn over. If it hadn't died after running a few seconds, i wouldn't even be questioning the fuel pump. Is there any way a starter or ignition switch can effect a running engine? I agree that the action of putting it up on and down off the flat bed dislodged something, a stuck selinoid, loose connection, or clog somewhere perhaps? I drove it home today, runs fine. I'll put it through its paces and let everyone know if it recurs. Definitely avoiding long road trips or awhile.

On a related but separate topic, my mechanic said something in passing to me about the auto tranny on these are notorious for problems at or past 100K...is this true? My extended warranty expires in Dec and that worries me if so.

 

[joegr]

...On a related but separate topic, my mechanic said something in passing to me about the auto tranny on these are notorious for problems at or past 100K...is this true? My extended warranty expires in Dec and that worries me if so.

Kind of...

 

[grizzlyls]

^^

To elaborate more, as a whole the 5r55 series transmission has some specific quirks. These are well documented and talked about endlessly here and other places on the web. My 2001 gen 1 5r55n tranny shifted hard when bought, and only needed shift kit springs and tranny maintenance. However, the second common issue the control solenoids appeared ok, but I told my mech, you are in there put the new one in. No extra labor and now all is smooth as silk.

Another issue is the PCM. When asked to diagnose whats up most of the time it seems the guys in the know here tend to look to the PCM repair through SIA and that fixes tranny shift issues. So far on mine that hasnt been needed, but I feel I am just counting time since mine was garage kept by a grandpa and grandma.

As for you, the 2004 gen 2 5r55s had most of the issues worked out, and if it has been regularly maintained you are probably ok. So many times the reference of a 'sealed' transmission is thought as no maintenance. Not true. Needs fluid change and checking just like anything else. With your warranty running out, if you have ANY sign of harsh shift, stall or whatever, you should talk to the dealer and see what they can do to get something done. Good luck, warranty probably wont want to pay unless its a 'serious' or hard failure.