Can anyone help me trouble shoot this? I bought this conversion 2 years ago, and have put 1500-2000 miles on it, and NOTHING I try seems to make any difference. It seems to run great, and has yet to give me any problems other than crappy mileage. No matter what I do, I can't seem to reliably get it above 15 mpg. I have tried going no faster than 55 mph (It runs at approx 2350 rpm at 55 mph) and not going above 2000 rpm when I take off. I use bio-diesel mostly, but I have tried dino-diesel to no effect also. I have street tires on it that are approx the same circumference as 31-10.50s. I have changed my oil to using Mobil1. The engine has approx 87-88k miles on it. The install was done by a gentleman who has done 17-18 of them, and looks very professional, and as I said it has run great for 1500-2000k miles..

Help?

(I'm new here, and if I'm breaking any forms of etiquette, let me know please.)

 

Welcome to the family... not to sure about the 1kz-tes my self though if gas goes up again I may look at the conversion... it could be a fuel metering problem or a problem with the fuel return line pissing fuel overboard rather then back to the tank. You ought to be seeing at least the low 20's mpg wise... does the conversion guy not have any ideas?