Flood a diesel?


Well-known member
Mar 1, 2004
Big Flat Prairie, Canada
2000 midnight blue
Is it possible to flood a diesel engine the same way you can flood a gas engine?

I was leaving IKEA yesterday (of course i shop at IKEA in my VW, its verry yuppyish). My car started fine, drove for about 10 seconds then puutered out and died (It wasnt the immobilizer). The engine would turn but wouldnt catch for a few minutes, but finally started (but very roughly, and low idle). I checked under the hood and it looked like there was air going through the fuel line from the filter but I'm not sure. After it ran for a bit it smartened up and ran fine since.

Not quite sure what happened? Any thoughts out there? /images/graemlins/confused.gif


Phd of TDIClub Enthusiast, Moderator at Large
May 1, 1999
For all p[ractical purposes, one cannot flood a Diesel engine in the same way as a gasoline engine, for many reasons. One is that the amount of fuel injected into the engine per stroke is very low; only enough to sustain the engine for the desired load and RPM. "Flooding" a diesel would require a serious malfuncion of the fuel injection system (e.g. broken spring inside the injector). There have been no documented cases of this ever happening, and if it were to happen, the result would a runaway engine, not an engine that would not start. What can and has happen is that oil is ingested into the cylinder, and since engine oil is basically fuel for the engine, such a relatively large quantity causes the engine to rev out of control.

What you experienced was probably air in the filter, as evidenced by the bubbles in the fuel line. Also, read up on the fuel sender issue that has plagued some cars... And also make sure your the relay 109 is OK. In fact, carry a replacement in the glove box always.


Aug 5, 2003
Tampa, FLA, USA
2000 Jetta, Dk Green
The short answer is "no". /images/graemlins/smile.gif

Not without a major problem. "Flooding" occurs when there is too much fuel for the amount of air. This generally won't happen on a TDI for 2 main reasons:

1) Diesels typically run with significantly more air than fuel in any given situation.

2) The amount of diesel being injected is precisely controlled by the ECU. The fuel is measured by the #3 injector, and the amount of air is measured by the MAF and MAP sensors. If the ECU and the sensors are all behaving, then you should have correct air and fuel amounts for the given situation.

As for the air bubbles, that might be a good place to sart looking. My car typically has a few tiny bubbles in the clear line...some cars seem to have a little, others seem to have none. But, an excessive amount of bubbles may be an indication of an air leak.

Another thing to check might be K109, a relay under the dash that controls the fuel pump, among other things. On the 2000 cars, they were originally black, and prone to failure. The main symptom was the car just died with no indication. Sometimes it would start back up, sometimes not. The new K109 is improved, and is gray. The relay is located behind your fuse box. Take a look at yours...if it's black, replace it. It'll cost you about $20 (US).