Strange No Start

[JonFord]

2003 Jetta, 170,000 Miles.

Ok, I drove my Jetta from Houston to Loveland, Co and parked it for 5 weeks. I come home from the Asia trip and have a no start.

1 Change the N109 guage out. No Start

2. Change the fuel filter, but still no start.

3. Finally figure that there is no fuel in the injection pump. The fuel tank was ½ full and the car was parked outside with less than a 5 degree angle.

4. Pulled vacuum on the feed line from the tank to the filter and had fuel there. I then hooked up to the back side (return fuel line) of the injection pump and no fuel.

5. I hooked the Mity to the return side of the injection pump, slowly poured fuel in the plastic see through line until the Mity started picking up fuel then re-hooked the injection pump see through line to the fuel filter and the engine started instantly.

My question is, what made the system pull fuel from the injection pump back to the tank????????

Is there a check valve that prevents this from happening or just a quirk to this model? I think that heating and cooling during the day and night was probably responsible for this, but doesn’t seem to be normal.

I loaded the dogs and headed for Houston at 80 mph without a problem. There are no starting issues so far.

 

[JonFord]

I guess I am alone on this one.

 

[2004Nick]

Jon I hope you eventually get some replies on this one very puzzling. Seems like you
took appropriate action to resolve it. Nick.

 

[whitedog]

Sounds like a small air leak on the injection pump.

 

[Joe_Meehan]

Sounds like a small air leak on the injection pump.

That sounds plausible.

 

[Baron VonZeppelin]

Probably just a very small minor air leak that will only take full effect with extended non-use. Not uncommon. It could grow worse though.

Thermostatic T on fuel filter has been a known source for suction leaks.

The hoses that jump from injector-to-injector and return to the Inj Pump, are also easy known sources. Including the block off cap on #1 injector.
Replace those hoses and cap, then wait and see if maybe the T needs replacing / deleting.

I'd start simple.

It could also be the main supply / return fuel hoses.
Clear/transparent hoses fore and aft of Inj Pump will give you spot-on diagnosis to locate any symptoms via visible air bubbles while running. Or air pockets forming while sitting.

 

[JonFord]

Thanks for the good info. I am about to change all of the vacuum lines and I will give all of those a good changing also.

It really seemed weird.