Cars do not run on air.

September 19, 2010 9:07 PM

I ran my 2000 diesel VW Beetle out of gas. Before taking it to the mechanic, I want to see if I can fix the problem. I'm pretty sure nothing I do will screw it up worse than it already is.

The problem with the diesel is that it does not have a push pump in the tank, so when it's run out of gas, the system sucks air and dies. I know (from reading and from talking to the mechanic who dealt with this problem before) that I need to bleed the air out of the fuel system. I gather that if the air is in the system between the tank and the filter, I can do this pretty easily. If it's between the filter and the engine, then the air has gotten into my injection pump and I'm screwed.

1. Am I correct in that understanding?

2. Does the system go tank-> injector pump-> fuel filter-> engine? Tank-> fuel filter-> injector pump-> engine? Some third thing?

3. Should I use a hand-held vacuum pump to pull the air out of the system (as recommended in comments here)? Or is it okay to try to force it out with the starter (as recommended here)?

4. Anything else that I should know that I probably don't? I do not have automotive experience, but I am good at following directions.

Tomorrow I'll hit Autozone and hopefully get a Chilton or Haynes manual for my car, which (hopefully) will give me step-by-step instructions. And starting tomorrow, I am never running the tank below 1/4 again.

posted by cereselle to travel & transportation (9 answers total)

There should be a bolt (9/16" / 17mm or 19mm, probably brass) on top of the injector pump. Pour diesel into the pump; it fills up, and ... it is primed. Or figure out where the diesel line goes in and use a turkey baster and some fuel line to push some diesel into the pump. Yes, this might result in some drippage; kitty litter, grocery sacks, oven baking pan; use some option to keep the diesel from hitting the yard/driveway/street.
Should be able to start and run a little; and maybe stall again; then prime again by filling the injector pump again. Should self prime after that.

- do not use starting fluid to force a diesel to run. = horrific damages.

1) yeah, but you just need to get it to run. VW diesels recirculate diesel that is not forced through the injectors back to the diesel tank. Once it does the wocka wocka wocka a few times it will be back to normal.
2) later is correct.
3) Can't hurt. And running out of diesel did not hurt your diesel. Or pump.
4) Skip this mess unless you have the tools, time, and skills; and call a mechanic to do the above. No harm done except a few bucks. FWIW a decent mechanic could do this w/out needing to even bring your vehicle into the shop. It is not rocket science.
posted by buzzman at 9:59 PM on September 19, 2010 [1 favorite]

- Don't burn up your starter or pump by trying too hard. This should be a 4-5 attempts to start At Most. 60k+ miles with VW diesels, yet IANYM.
posted by buzzman at 10:07 PM on September 19, 2010

make sure to take off the fuel filter and top that off before running. If you don't have a filter wrench, then buy a new filter because the only other way to get it off is to stake it with a screwdriver.
posted by Jon_Evil at 10:17 PM on September 19, 2010 [1 favorite]

This is not a big deal. Here is a very detailed set of instructions for dealing with this problem from TDIClub (which is a very good resource for any questions about your car).

Don't stress about this - even if you have air in the injection pump, you can fix this if you want to. This has happened to family members before and it was always fixed without having to bleed the pump (don't be afraid to let it crank a little bit).

The go-to repair manual for the car is published by Bentley, but it is expensive (people don't seem to think much of the Chilton, etc. manuals).
posted by ssg at 10:23 PM on September 19, 2010 [1 favorite]

I don't think this pump has a filler bolt the way some other diesels do. Best to fill the pump using a hand-held vacuum pump as in your link -- I've done it quite successfully a couple of times in a 2001 TDI.

Since it sounds as if the car died while it was running, that means you sucked air into the hard lines between the injection pump and the cylinders. Air is compressible, which will make it impossible for the injectors to "pop" open when the engine is cranked. If you can't expel the air in the lines, you'll never get fuel to the injectors. You'll have to crack the injector lines open a tad at the cylinder, one by one, and crank until you get fuel leaking out. (Wrap a rag around the nut to prevent the fuel from going very far.) It might take a few tries to get fuel out, but when you do tighten the injector nut back up and move on to the next cylinder. You should only have to bleed two or three lines to get it to start. The injector nuts are pretty easy to reach, and take a 15 or 17mm wrench (I forget which).

If you're not comfortable doing any of this, any competent mechanic that has experience with diesels (very important!) should be able to do this in your driveway in about 10 minutes. If you don't know anyone that fits the bill, ask on TDI Club's Southeastern USA forum. You'll get some good recommendations there for sure. Good luck!

on preview: buzzman's comment about the starter is a good one. Crank for no more than 10 seconds, then take a break for at least 5 minutes to allow the starter to cool. And Jon_Evil, the fuel filter is not a spin-on in this car, so it's very easy to access. The best way to fill it is by removing the plastic fitting held onto the body of the filter by the "mickey mouse" clip.
posted by harkin banks at 10:23 PM on September 19, 2010 [1 favorite]

If you don't have a filter wrench, then buy a new filter because the only other way to get it off is to stake it with a screwdriver.

Not on TDIs. You just need pliers to detach the hoses from the filters (and your fingers to detach the t-fitting clip). You don't need to move the fuel filter itself, though if you want to move it up a bit to make things easier, you just loosen the clamp around it with a Phillips screwdriver.
posted by ssg at 10:26 PM on September 19, 2010 [1 favorite]

I just got through doing this with a 2003 Beetle TDI.
harkin banks description above is is good - I used a hand pump to suck fuel through
the filter to fill it, then through the pump. It still wouldn't start until I cracked
the hard lines at the injectors, but after I did that it started right up.
Other reason to avoid just cranking it is that the injector pump is lubricated
by the fuel - not a great idea to run it while it is dry.
posted by yetanother at 11:13 PM on September 19, 2010

Another comment specifically about the Beetle - the filter is a little more difficult to get to than it looks in the pictures from the Jetta, but it is the same place, and you should be able to see everything easily.
It is just going to be a tighter squeeze getting a pair of pliers in there to get the clip off the line at the filter, and then get your hand in there to free the line. The hint from ssg about raising it could be good - seeing that earlier could have saved me a skinned knuckle.
If you are removing the T fitting tie a piece of string to the clip before you try to replace it - it has a nasty tendency to spring out of your fingers and hide when you try to push it in.
posted by yetanother at 11:41 PM on September 19, 2010

A few more comments given your lack of automotive experience:

If you have never taken the plastic engine cover off it is very easy, but you will need a 10mm socket with an extension (the nuts are down holes a few inches deep), and a 10mm wrench to loosen a nut at the back that holds it on.

The clips on the fuel lines are easy to work with as long as you can get to them. Just squeeze the ends together and slide the clip along the hose past the end of the fitting. Getting the hose off the fitting can be more of a challenge - they tend to stick. Be careful not to damage them.

Don't drop anything into the engine compartment.
If you do drop something into the engine compartment and your car still has its belly pan then you will probably need a jack and some axle stands to get it back unless you can fish it out with a magnet. There is very little room to get under the Beetle without getting it off the ground.
Do not try this with just the jack that came with the car. Seriously, don't even think about it.

Keep your hands and everything else out of the engine compartment whenever the key is anywhere near the ignition switch. Even when the key is in your pocket assume that all belts and fans can spring into life all by themselves, so keep your fingers away from them.

Don't forget to check the fuel lines one more time after you have it running - you really don't want them leaking fuel out, or air in.

If you get stuck or lost just follow the advice above about getting a diesel mechanic and explain to them what you have done so far. You are unlikely to do anything to make it worse or more expensive if you just take your time, keep everything clean, try not to get too frustrated when the hoses don't want to move, and pay attention to the safety warnings in the links above.
posted by yetanother at 1:29 AM on September 20, 2010