Hard "cold" actually cool Starting - 2006 Jetta TDI 5 spd

Ok, don't laugh as 50 degrees isn't cold. I live in Houston and it has gotten relatively cool the past few mornings. Monday I went to start up and it fired immediately but then died. Car always starts immediately within turning the key. Turned the key to start, fired immediately then died, don't recall but probably just got in and turned key to start immediately as normal. Cycled key off/on and waited for the glow plug light to go out... no fire at all just cranking. Tried to cycle glow plug again and same thing, crank but no start. Finally decided to just crank on it w/ throttle input and it finally started.

Absolutely no noticeable slow crank, so the battery seems to be enough power.

Tuesday, 50 Fexactly same thing, though I made sure to wait for glow plug light to go out, turn key to start, fire immediately then die. Keep cranking and nothing for about 5 seconds then w/ throttle input I get it to start.

Wednesday, 44 F same routing. I actually tried to cycle key a couple of times prior to initial start but still have to crank for a while to get it to fire and stay running.

After the initial fire there is no sputtering or anything, just smooth crank until it fires up and runs fine.

No noticeable poor running or anything.

Had battery load tested at auto parts store and it checked fine. (my superduty will crank fine but if one battery is bad of the two it won't start for anything without a lot of cranking... no such luck here, was hoping battery was possibly weak).

Will make sure that when I first attempt to start tomorrow morning that I hold the key when I first turn it until it starts, but I don't think this is the issue.

Checked codes, don't have any.

Has anyone experienced this before? Bentley book say won't turn on glow plugs until 40 some degrees?

Absolutely no driveability, idle, performance issues whatsoever. Once it starts in the morning it is good for the rest of the day. Sits all day long, 10 hrs and come outside to start generally 80F or so and it starts perfectly.

So I am confused and can only think that it is something to do w/ glow plugs.

I do have a tune on the car but it was there all last winter and it was well below freezing without any starting problems at all. Nothing that I know of has changed besides another year on the car. I did change the clutch so I guess it is possible that I didn't get something plugged back in which I will check.

Suggestions? Thank you, Jason

Kinda sounds like your looseing fuel prime. Are you cetrain your lift pump is operational? When cycling the key you should hear the lift pump run. Some help makes it easier, atleast for me and my bad ears, you can listen by the filler neck or under the car.

This seems to be happening more often, mainly because I have quit driving the car as I purchased the 2010 TDI. Main problem is it isn't consistent.

I drove the car last on Monday. Parked in driveway, went to start this evening (70 degrees out), cranked the car (making sure to crank till it runs, immediately fired (still holding key in start mode) and it died. When it died I kept cranking it.

I agree it seems fuel related. When I turn key off and back on, it seems that the lift pump is working, I can hear buzzing for a short period of time. I tried to cycle key a few times attempting to prime, still had to crank it for about 20 seconds or so, finally starts up and runs fine. Will the car run without the lift pump operational?

Is there a way to test to make sure the lift pump is working? I guess I could pull one of the fuel lines off somewhere coming out of the filter to see if any fuel squirts out when cycling the key.

Has anyone ever ran across a venting problem? I had that on a semi before, run fine down the road, however vent wouldn't let air into tank as fuel was sucked out. Park semi after driving fine for 100 miles, a vacuum was created in the tank and it in turn sucked all the fuel out of the filters. Went to start and no fuel!! Bled all air out and it started fine, come to find out a mud dauber had plugged up the vent in the tank! Clean out vent and no problems!!

I have opened up the fuel cap after driving for a while and I don't hear a sucking in of air so I don't feel as though I have venting problems.

Any suggestions? I am trying to sell the car and I really don't want to sell someone else a problem, I didn't like it with all the problems I unknowingly ended up with.

Thank you, Jason