93 smoke with 99% biodiesel

[Sri Ram]

My buddy's 93 (club cab/chassis, 4x4, 4. 10, 80+gal fuel tank, stock engine/inj pump) smokes on soy biodiesel, he says especially at 2000+rpms, even at opterating temp. Runs "normally" on #2…Air filter looks clean…Why the smoke? Any thoughts appreciated. (Also posting in Alt. Fuel forum)

 

[Greenleaf]

Soy oil is tons more oil-le-'er than #2 diesel. Fact the last seminar I attended 'bout soy fuel, it was mentioned that 5-10% soy added to ULSD fuel will give loads of additional lubricity.



Althought the confusion still resides in the fact that pure #2 (of 5000 ppm sulfer) is a bit heavier than some/most bio mix in terms of BTU content... ... ... ... ... ... ... ... . right?

 

[Sri Ram]

Soy oil is tons more oil-le-'er than #2 diesel. Fact the last seminar I attended 'bout soy fuel, it was mentioned that 5-10% soy added to ULSD fuel will give loads of additional lubricity.



Althought the confusion still resides in the fact that pure #2 (of 5000 ppm sulfer) is a bit heavier than some/most bio mix in terms of BTU content... ... ... ... ... ... ... ... . right?

Uhh, yes that is my understanding. So, why would increased lubricity or slightly lower BTU content create smoke? Wouldn't smoke mean unburned fuel, or is that not the case when running soy biodiesel?



BTW, I run the exact same fuel in my 91 that my buddy does, and I have had no smoke except on startup (and on the dyno ).

 

[dpuckett]

Could be a myriad of factors. With the lower BTU content, it would stand to reason that one would need to advance timing a degree or two to make up the difference. Also, if the bio is thicker than the petro, it could have an effect.



What color is the smoke? Is it white/bluish, or black/grey? Could be injector issues that are exacerbated by the bio fuel.



Daniel



Anyone know where to get bio in MO?