hard start after sitting a week then runs and starts normal.

[Andrewh]

06 jetta tdi. 42k miles.
I don't drive it much any more.
so it I use a trickle charger to keep the battery up.

it might run once a week. I get it to operating temp, but still don't drive it far.

a few times, not every time, after sitting like this, it won't start right away like normal.

I will have to crank for a long time, several times with the gas pedal on the floor, till it finally starts to build up some revs and catches.

I have tried "priming" a few times, this last time.
key to on, without cranking, off, then to on again 3 or 4 times, hoping, if it was a fuel pressure issue, it would then start, but that didn't seem to matter.

cranking for 30 to 40 seconds at a time, till the low oil light comes on, 3 or 4 times, then it finally catches.

I read something about bad lift pumps, but I thought that might be a more consistent problem.

what else should I be testing?
if I take it out every day during the school year, I don't see this happen.
I do recall once it happened, after a short move, from the garage to the driveway, the next day I had to do the same thing, but that hasn't happened in a while.

this has probably only happened 6 times in the last year.

 

[Maffken]

If it's only after it's been sitting for a longer time period I might think that the pump is loosing its prime and fuel is flowing back into the system. This can happen from degraded seals and hoses.

I've heard of people putting fuel rated check valves into their fuel feed lines to prevent this from happening. Worse case is nothing happens, best case is that it works well. I'd try it (It should be pretty cheap either way).

Just a guess but since it seems to run well after its been run frequently and not when its been sitting, much like when you dump the fuel from the filter/IP and have to crank to get it back (don't do this, priming is better but I understand it someone has).

A bad fuel sending unit could also cause fuel restrictions and the filter. I'd pull fuel from the whole system (tank/filter) see if there are any restrictions and go from there.

 

[Andrewh]

so a couple of things.
first, wouldn't a fuel restriction still cause other problems?
right after, I was on the freeway following traffic pretty fast. no issues on accleration, no issues running at highway speeds +.

as for losing prime, I did try and prime it several times.
am I not trying enough? air need to be purged?

where are they putting this check valve?
Am I taking the pump out of the gas tank?

 

[MyAvocation]

Just a guess, but I suspect air must be purged through the tandem pump, which is only accomplished by cranking.

+1 on Maffken's diagnosis. Several members fixed this by installing a check valve. Just search this forum with search terms like, "check valve hard start" to figure out which hose.

BTW, this happened to me once about 4 years ago. So for other readers, an isolated incident of hard starting after sitting a week is nothing to be concerned about.

 

[Andrewh]

thanks, will look for other posts now.

 

[dbdubb]

Sell it to me and buy a gasser. These cars aren't meant to sit around.

 

[Andrewh]

lol, yours is already nicer than mine.
package 1 and no euro anything.

 

[ZeroCool]

hmm...

This sounds very familiar to the issue I had on my 2005.5

Car could run fine for weeks.. then i would get a hard start issue where sometimes I would have to keep the pedal to the floor and would get the oil indicator warning light before I would hear the car start to catch.

Have you checking your timing?

I had my checked found it was at 2.5 ... had it adjusted and the issue seemed to go away for the most part.

 

[Andrewh]

I changed the timing belt about 2k miles ago.
I don't remember what my setting was, but it was way under 2. probably 1.