Car won't start when engine is warm

This past Monday I went to start my car to go to work it sputtered like it wasn't getting fuel, but then ran fine after a few seconds. Same thing happened hours later when I went to lunch. Then again when I was going home. A few hours later I drove it about 20 minutes and it sat in the parking for about 90 minutes. This time the car sputtered, ran for about five seconds, and then died. I never could get it to start after that. The engine would crank, but that was it. The next day I towed it to the dealer 45 miles away because I thought it could be a problem with the HPFP. It started right up for them, and they suggested replacing the exhaust flap on the engine. He said that was seized up, and could be causing the problem. They checked the fuel filter, and there were no metal shavings in it. I picked it up on Wednesday, drove it maybe 12 minutes down the road, stopped to eat, and then drove it across the road where it sat for about 75 minutes. When I went to start it this time it did the same thing. Had to have it towed back to the dealer later that day. Of course the next morning it starts right up for them. I suggested that it's only happening after the engine has warmed up and left to sit for a while. They were able to duplicate the problem yesterday, and have been working with VW Tech Support to diagnose it. Their suggestion to the dealer was it is in the fuel system, and they narrowed it down to faulty injectors or a check valve not closing. They said the injectors would throw a code if they were bad, so they don't believe the problem is there. They told me the valve is not closing to build up pressure for the engine to start, and it's letting fuel flow back in to the tank. After the car gets started it runs fine. So, that is their next part to replace. Does this seem like the probable cause? My searches for a faulty fuel check valve only seemed to results for the car parked on an incline.

http://youtu.be/wEBpdblovDY

1 never take your car to the dealership. 2 dont own an 09' 3 find a local club mechanic. The dealer is just gona throw parts at the car at your expense. Hopefully someone with some knowledge will be along shortly to assist you.

I normally take it to my local mechanic. The only reason I took it to the dealer this time is because I thought it was the fuel pump.

It sounds like the dealer you are working with it going down the list of logical causes... not all dealers are bad, some actually know their ****.

GreenLantern_TDI said:

1 never take your car to the dealership. Seriously? If everyone followed this advice, there would BE no VW sales in the US.
2 dont own an 09' Not very helpful for those of us, including the OP that is asking for advice, that already own 2009 CR TDIs.
3 find a local club mechanic. The dealer is just gona throw parts at the car at your expense. Hopefully someone with some knowledge will be along shortly to assist you.

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I've had excellent service at 3 different VW dealerships. I will continue to support my current VW dealership.

Of course, incompetent dealerships and techs aren't acceptable, but good dealership techs exist, and should be supported.

Absolutely support good service vendors. As stated above, there are many good dealers and good service techs. Unfortunately the bad one's get the attention and the good one's don't.

After reading the post and dismissing the usual about certain years being worse than others, it would seem that you're experiencing a lack of fuel. Since no warnings and no codes it's a fair bet that the problem resides in an unmonitored part of the fuel system.

I assume (because I don't know for sure) that an open circuit to your fuel pump would be reported to the ECU. Same for a short. This doesn't rule out the pump, it only tells me that the circuit is likely good.

One of the things I wouldn't rule out is an air lock somewhere in the system allowing fuel to drain from the supply line. Honestly I'd be more inclined toward a pump problem but these nagging problems can be more frustrating than a hard fault.

This is one of those frustrating times when elimination and logic will rule the day. It would appear that your tech is doing more than blindly throwing parts at the problem, and that's a good thing.

One thing of note... A4's had a check valve mounted atop their fuel filter. If the valve failed, then it allowed fuel to drain back into the tank especially if the vehicle was parked with the nose pointing up a small incline. Your car will not be the same as the fueling layout is different. All the same I'd want to make sure the system isn't simply draining down and somehow airlocking the pump.

Shortly after changing my fuel filter I had the same problem. I did run the fuel pump with VCDS.

The problem lasted maybe a month or so and went away. I atriributed it to somehow a bit of air in the system that never worked its way out...


Somewhere on the forum, I have seen other people with this mystery problem but no solution. One was to replace a check valve, another to replace the starter, and a third was to assure the battery voltage was good.

The latest on this is they're still working with tech support, and have elevated my case to level two. They replaced the check valve, and that did not fix it. VW authorized them to replace the in-tank fuel pump, and that wasn't the problem either. This morning they were supposed to be monitoring the pressure at the fuel filter housing. I assume that was ok, but I did not hear back specifically. Now they would like the drain the fuel tank, clean it, refill it with diesel and change the fuel filter. The tech at the dealer doesn't think it's a contamination issue, and neither do I. If it was contaminated it shouldn't run at all, but when it starts it runs fine. I have advised against doing this last step, so I'm not sure where we're at now.

Keep us posted! I for sure am curious... Mine went away as mysteriously as it came

Check the battery if the ECM doesn't receive the right voltage it will not start. These ECM are very picky about the voltage.

They are cleaning out the fuel tank and said they found a small trace of gas. I don't see how the engine would run at all if there was gas in there, so I'm not sure what to think at this point. I of course have only ever put diesel in, and I have the misfueling guard on. My hope is it will run fine after the cleaning and there was no damage caused. The next step was to replace the HPFP if this didn't work, and I'm sure VW won't cover the cost if they can blame contamination on me.

How did they determine a small trace of gas? I call BS on that one. The HPFP can be tested for pressure output via vagcom and inspected for metal bits by removing the pressure regulating solenoid. No need to guess and replace a good pump. Tiny amounts of gas, while not good for the long term health of the HPFP will not cause your symptoms. Tell them to rule out the HPFP and then move on to electrical, as at this point everything will have been replaced or tested to be good in the fuel system.

"...small trace of gas...". Ridiculous. Not even worth discussing.
If they can say that to you with a straight face, then your problems are no longer limited to your car, but are compounded by their ignorance.
So sorry about all this.
As was stated above, how's the battery?

How far is Shelbyville from St. Louis? Member Oilhammer is there and the best indy tech in the region.

The dealership is emptying you bank account due to incompetence. Here's your clue: Fuel check valve, seriously? That defect manifests during cold starts, not hot. I know this is not a BRM, but wiring harness is a possibility. Has any other A5 CR owner had harness issues?

Battery could definitely be it, also being in the rust belt it could also be a bad corroded ground, especially the lift pump. I had a similar issue in a gasser once, turned out to be a bad ground for the fuel pump, a real bugger to figure out. Also worth looking at the connectors for corrosion.

^^^ALL of which should have been checked FIRST by the first tech to look at the car!

Well, the dealer has called and my car is fixed. They said it is "running like a champ". I will have to post the comments on the bill to see exactly what all they did after I pick it up in a few hours.

St. Louis is about a 4.5 hour drive from me. I'm close to Louisville.

Cant wait to see what they did to fix it ... I hope the problem didnt just go away mysteriously and them throwing parts at it had nothing to do with it "running like a champ"

Any update as the what the problem was?

I'm too curious.. any update on this from the dealer?