Auxiliary Pump for Running WVO?

[mountainibis]

I'm a newbie both to the site and to Cummins motors. So, if this has already been discussed, I apologize. Whatever the case, this is a great site, and I'm glad the guy I bought my truck from had a TDR sticker on the window.



A few months back, I swapped a two tank WVO system from my old truck ('02 Chevy Duramax) to my new ride ('97 Dodge Ext. cab 4x4). The kit had an inline auxiliary pump on the veggie oil side, which I assume was to help the Duramax out, since it didn't have a lift pump.



Do I still need to run the auxiliary pump, or is the lift pump on the 12 valve stout enough to pull the veggie oil from its tank? Also, if it's best to keep the pump, would the pressure need to be regulated?



Thanks in advance for the help.

 

[salty]

NO! You must use the mechanical lift pump on your 97, which is a robust unit. If you bypass it... it will pump away anyway as it's driven off the camshaft.



What you need to do is "undo" all the plumbing between the tank, pre-heat screen,LP, diesel filter,and IP so the LP is last in line pre IP. LP pulling Vs pushing. Hint: seperate the pre-heat screen from LP as well so that Veg does not go through it.



Diesel tank - screen- diesel filter-solenoid A (feed) - LP - Vegtherm - IP

Return from IP and Injectors combined and sent to solenoid B (return) - diesel tank.



Veg tank - veg filter - solenoid A (feed) - LP - Vegtherm - IP

Returns from IP and Injectors combined and sent to solenoid B (return)



In "purge" mode diesel is fed through solenoid A (feed) but solenoid B (return) loops it back to the pre veg filter and ultimately to the Veg tank. Once purge is complete switch back to diesel which activates solenoid B to return to the diesel tank.

 

[mountainibis]

I appreciate the response. I think my system is a little different than what you're describing, though. I only have one solenoid. Supply and return for diesel and veggie are plumbed into the solenoid, which controls what gets sent to the motor. I control the solenoid from a switch in the cab. The same switch also controls the auxiliary pump. The veggie oil gets its heat from a coolant baffle in the bottom of the tank and coolant lines wrapped around all fuel lines and the pre-filter.



When I switch from veggie to diesel, some veggie goes to the diesel tank. Am I right in assuming that a two solenoid design would prevent that from happening? Are there any other benefits to using a two solenoid design?



As of now, the flow of veggie is: tank - veggie filter - auxiliary pump - switching solenoid - stock filter... Is that the best way to do it, or should I be plumbed into the stock lines somewhere else?



Thanks again for the help!

 

[salty]

To be clear, I know what I know, but not what I don't yet know... so I can only share my concerns based on my experience. There are always several workable approaches.



Here's what I'm concerned about with your system:



What is the piston driven LP doing when you have activated the electric pump? Or is this secondary pump just in addition to the LP? The LP in a 97 is mechanical and stout. It will pull veg just fine, but if when on veg you are bypassing the LP it's just going to be working anytime the engine is running, so you better have a method for it to cycle fuel back to the diesel tank. I am still not clear on this.



Veg into the diesel tank is in my mind not desireable. Over time the veg concentration will strengthen and you do NOT want any veg sitting in the IP during shut down. As this concentration could get fairly significant over the miles / circumtances of driving, you will be pumping a cold mix into the IP at start-ups.



The thing about the two tank system that is so nice is that you have two seperate fuel systems that share the same LP and both somenoids. No veg gets into the diesel tank, and only diesel gets into the veg tank during purging (not an issue). This means the system is completely void of veg during shut down and primed for a clean start. You only introduce veg when it's HOT. My Bosch / Cummins shop owner loves the fact that there's no veg in the system when it's cold and believes this to be the reason for my success, as well as the reason for the many biodiesel trucks in his shop... . gelled injection systems.



If I were you, I would add a second solenoid and plumb as I outlined. I think you'd find it to work flawlessly. Having said that you may be fine as is. Those are just my thoughts / concerns.



Salty

 

[mountainibis]

The auxiliary pump is in addition to the lift pump. When running on veggie, both run. If the LP is strong enough to pull the veggie, I'll take out the auxiliary pump. There's no sense in having more equipment and wiring than necessary.



I'll also look into installing another solenoid. I'd rather do that than gum up the injection system.



Thanks again for your help.

 

[salty]

Provided the veg is warm the stock mechanical LP will be more than adequate. Mine went 300k and when I changed it after running WVO for a couple of years (just for good measure) it looked perfect internally.



I think you'll be very happy with a feed and return solenoid.

 

[VeggieCummins]

I used a Fass pump and filter on my 06. That had the intank pump though so it was amust. I want a 12 valve to run wvo