bio diesel fuel economy

[mdedrick]

I have two 6.2 diesels-a 82 suburban half ton w/3.73 gears-R4 trans and a 86 CUCV w/turbo and recently changed rear to 3.73. I am not getting the mileage I should-10 mpg or so with both vehicles. I changed the fuel filter with the CUCV when I started using the bio, but that has not helped much. As far as I know I should be getting 16 mpg plus with the cucv and maybe 20 with the suburban. Do I need to change the fuel filters more-they were never run on bio before? I changed the glow plugs and the cucv starts better. They both run well-its just the mileage. Thanks mike

[Mr. Bone]

Hello,

I've been running B-100 for a couple of months now. Haven't noticed a big difference (if any) in fuel economy)

You definitely need to change your filters out. BioD is a solvent and will loosen up all the residue in your fuel lines and tank consequently clogging your filter. I recommend beginning with b-10 or 20 and working your way up to B-100 if you have that option. You will probably need to change your filters out 1 or 2 times.

Hope that helps.

[johnny2can]

Bought my '86 'burb almost a year ago and switched to biodiesel after the 3rd tank.

Went straight to B99.

Custom blended to B60 during the winter to avoid gelling at lower temps.

Changed the first filter after 4 months (roughly 10 tanks?) just 'cuz I thought it needed it, but there was no indication that the filter was clogged. Within two weeks, WHAM! the second filter was clogged (Water in Fuel light came on... I assume that's a differential pressure switch across the filter? 99% positive there was no water in fuel). Changed that filter about 4 months later (procrastination) and have been running since.

Started with 16 MPG, now averaging 17 MPG with more power (gradual increase in both MPG and power, assume it's because everything's getting cleaned out). I'm sure I could get more with new IP, timing gears, and injectors (they are original).

Only "issues" re: bio is that some of the rubber fuel lines are "weeping" (v-e-r-y slow leakage of fuel through the jacket)... I expect to replace the fuel lines and pump this summer.

Based on my experience, your MPG problems lie elsewhere, not with the biodiesel.

[Slim shady]

I to have been using Bio diesel B-20 for about 2 years now, and have not had any mileage loss. In fact I have picked up about one mile to the gallon with a lot smoother running motor. The fuel filter did need to be changed twice and I have not had any issues since then.

I would check your timing, Bio diesel can be run with a higher initial base timing. It will run smother and have more pep. I suspect the fuel filter may be restricted limiting your fuel supply, this could give you reduced power and mileage.

[moondoggie]

Good Day!

"...82 suburban half ton w/3.73 gears-R4 trans and a 86 CUCV w/turbo and recently changed rear to 3.73." How's your driving style? mpg always drops with increased speed; these engines seem to really drop off a cliff (mpg-wise) over 60-65 mph.

I had an 84 4WD Sub with the same gears. It ALWAYS got > 20 mph on the highway. But, I never speed - I drive whatever the speed limit is. In MN, that means 55 mph on 2 lane roads, 65 on most limited access, & 70 on some limited access.

Blessings!

[mdedrick]

I have an 86 military pu and the glow plug controller dosent always cycle. Do I have to get a special military unit to replace this part (the mil versions use a 24 volt system to run the glow plugs, as I understand it) or will a standard GM controller work and plug in to the existing military parts. The truck is unmodified.
Thanks to all who replied to my bio diesel mileage question-very helpful

[moondoggie]

Good Day!

Unfortunately, I can't answer your question. Even more unfortunate, it's highly unlikely anyone will, since you've essentially asked a new question. I strongly suggest you start a new topic to get your answer. ;)


Blessings!
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