2007 VW Rabbit went from hard to start occasionally, to not starting. Best places to look?

Question

My VW Rabbit has had issues starting for the past few years. Last week, it stopped starting all together. Here are some of my observations and testings

• The car did not run rough once it did start previously
• There is no check engine light on now or before
• I just changed the spark plugs and air filter
• It is not the battery as I charged it up with an external charger
• The engine does turn over fine with the starter. I do not expect the starter is at fault.

One interesting thing to note is it does start weakly for about about 1-2 seconds after it has sat for a while. The next time, it will not.

With no error codes being thrown, I am at a bit of a loss as to what to do next except just start replacing parts which I want to avoid. I thought the VW computer could detect if the ignition coils were bad. I also am a bit confused as to what it could be that it would run fun once started up to this point. Any ideas are appreciated.

Answer 1

Since the vehicle is sort of starting for a couple of seconds, I'm pretty sure we can rule out the ignition as an issue, as well as compression. The first place I'd look and which is probably at fault is the fuel pump isn't pumping, or the fuel filter isn't allowing fuel to pass. Either way, your first step is to check fuel pressure at the fuel rail to see if it's putting pressure. You can only really do this with a fuel pressure tester. I believe you can "borrow" one from most major brand parts stores.

Something else you can do is to check your oil. Is it overfull? Does it smell like gas? (If fuel is leaking through the injectors, it will leak down past the rings and into the crankcase, thus giving you too much "oil" and the smell of gas.) If so, you might be getting way too much fuel with a stuck injector(s). If the engine was flooded, it would not want to start. Plus it could also be the reason it has not wanted to start well for the past while (extra fuel in the combustion chamber at startup due to fuel pressure bleed off after engine stop). You could also see this with a fuel pressure tester, as after ignition shut off, you'd see the pressure drop off over time (might happen quickly or might happen fast).

Any which way, your description leads me to believe you have a fueling issue and not a problem with spark or air.

Answer 2

The first things to check is:

1. Does it have spark at the spark plugs. You can purchase a spark tester at auto parts store.
2. Is it getting fuel to the fuel rail? You can get a fuel pressure gauge.
3. Do you have compression? Tested with a compression tester. If you can't or won't start with these tests, you can take it to a shop for diagnosis. Usually cheaper than throwing parts at it.