The front pump seal can sometimes suck air, but it usuaully manifests itself first as cutting out under high power. I suppose if it were to suddenly fail the pump would suck air and the engine would quit. You won't see bubbles in the fuel inlet line in this case, you'll see lots of foam in the return though. If the stupid thermostatic "T" is happens to be stuck open (frequent failure) and recycling the return fuel into the inlet it will quickly fill the system with air and quit. You can diagnose the front seal by removing the thermostatic "T" and plugging the hole in the filter with something (your thumb?) and firing it up. If the seal is leaking the inlet line will be free of bubbles but the outlet line will be foamy or milky looking.
Topic: 98 Jetta TDI (Read 7457 times)
