Former VWDieselParts.com Forum

I just finished swapping an AAZ into my vanagon. It runs great! I ran my first tank of WVO biodiesel today and It runs fine untill the RPM's get high and then it acts like its running out of fuel.(jerky lack of power until I back down on the pedal and it runs fine again.) I have a 2 tank system and when this happens and I switch it to dino it immediately runs fine again. Both tanks use the same filter so I'm ruling that out. My timing is set for .034. Haven't pop tested my injectors, but I rebuilt them with new nozzles. The previous engine (Stock 1.6 diesel) ran fine with the same batch of bio. I'm wondering if the AAZ injection pump timing needs to be advanced a bit for Bio.? What do you guys think? Thanks, Paolo

Just did som research and I had it wrong about "advancing" the IP timing, I guess biodiesel burns quicker than dino and thus benifits from a more retarded timing. Would running biodiesel with an overly advanced timing create the symtoms I have? Thanks, Paolo

I dont use BD, but it way eazy to have separate filter,even inline for D is ok for me.
I use advance as better.
It look like you need more BD in uper RPM-restriction same place,mostly filter.

Sounds more like fuel starvation.
A vacuum gauge on your fuel line will let you know if there is a restriction.

Vince, you nailed it! I installed clear lines and indeed I was getting a whole bunch of air at high rpm's. It was leaking in from a fuel fitting. Runs great now. Thanks for the help, Paolo.