I recently did the conversion to WVO with the mercedessource kit and things were going well. As I started adding more WVO to the tank and got up to around 90% WVO and 10% Diesel I noticed the engine starting to hestitate after running it for 10-25 minutes. It began by hesitating at 75 on the freeway, every five minutes it would get worse and worse until finally I could only get the car up to 25. The filters looked fine so I tried adding 5 gallons of diesel fuel and the problem started to go away as the diesel got mixed in, acceleration came back.
I noticed though as the tank got lower and lower the problem seemed to return and seemed to be temporarily alleviated by adding more diesel. But then the problem would return again. Now I'm running almost 80% diesel and the hesitation problem is creeping up again.
I checked the final mesh metal filter going into the engine and it is clean. The plastic prefilters by the gas tank and before the big 5 micron filter are also clean. I've been filtering my WVO down to 10 micron using filter bags.
I've read through similar problems and have a few ideas but would like some input:
1) I didn't remove the screen on the auxiliary fuel pump by the gas tank (I doubt this is the culprit but could try removing it anyway).
2) Old tired mechanical lift pump?
3) Air seeping in somewhere?