adding a boost pump to WVO system? - PeachParts Mercedes-Benz Forum

wilburtual · #1 11-07-2011, 01:27 PM

i am wondering if i should add a 12v boost fuel pump to my single tank system to give the merc fuel pump a little help with the WVO? i see 12volt generic 5-9 psi fuel pumps on ebay for about $35, so its not a huge expense, just wondering if that really does help anything? could it hurt anything? is 5-9 psi enough pressure for adequate fuel flow?

Low Pressure Electric Fuel Pump gas,diesel, 12V 6-9 PSI | eBay

Biodiesel300TD · #2 11-07-2011, 02:04 PM

I'd recommend using one. The lift pump isn't designed to pull thick veg oil through the system. So all the help you can get I would go for it. I used a Facet PosiFlo pump in my two tank system. Works great and had for nearly 60k miles. It supplies 4-7psi.

bmor_62 · #3 11-07-2011, 09:22 PM

from mercedes source web site...regarding their 10 psi Walbro lift pump ($170)

"PERFORMANCE: Adding a boost pump can do a number of things for an older Mercedes running on diesel fuel. Over time the injection pump and mechanical lift pump wear internally to the point where performance will begin to suffer primarily showing up as a loss of power, especially when the engine is cold. When running thicker fuel such as B100 biodiesel or SVO adding this pump will do wonders to take the strain off the engine pump and increase fuel pressure and increase filter life. This newly released Walbro pump is the best demand pump on the market and well suited to move diesel, biodiesel, and SVO from the fuel tank to the engine. The pump runs only on demand at 10 psi pressure, is quiet, and draws less than 5 amps. Inlet and outlet are standard 1/4 female pipe threads so a number of different standard fittings can be used if you require a hose size smaller or larger than 5/16 inch I.D.ADDED BONUS: It can also be a great aid in fast bleeding air out of your fuel system after a filter change or other maintenance. This is very important when running SVO as the factory hand primer pump just does not have the pull the move heavy vegetable oil from the tank and through a large filter. Some customers have praised this pump for this aspect alone. Instead of taking 15 to 20 minutes to bleed your SVO fuel system after filter changes you will have the system bled of all air in less than 2 minutes!"

Biodiesel300TD · #4 11-07-2011, 11:47 PM

$170 for a pump. Don't wait the money. The Facet pump is just over $50.

wilburtual · #5 11-08-2011, 12:42 AM

what sort of PSI does the pump need? i see pumps from 4, 9, 12, 14 psi,etc.. can too much be a problem? i know i've seen a couple guys use the airtex which i think is 10-14 psi. they are around $54
which facet do you have? does it just run constantly (ie i wire it to go on with ignition and just run?)

wilburtual · #6 11-08-2011, 12:47 AM

was your facet like this:?

Facet Solid State electric fuel pump - 40107 - Discount Yacht Supplies, Vetus Nautical Accessories, Scandvik Parts, Garmin Marine Electronics

Biodiesel300TD · #7 11-08-2011, 08:28 PM

Nope this one is the one I use

POSI-FLO 12 VOLT FUEL PUMP 610-1051 ~ NAPA ~Universal Electronic Fuel Pump ~ NEW | eBay

I've seen the one in your link work as well. Either will do.

I got mine at my local Napa, they're usually on the shelf.

wilburtual · #8 11-09-2011, 02:32 PM

cool, thanks. do these 12v pumps pass fuel if they lose power or fail? or will it just stop the fuel flow all together and the engine dies? i am going to add one either way, just wondering for troubleshooting purposes.

Biodiesel300TD · #9 11-09-2011, 04:35 PM

I'm not sure. I never had problems with mine.

funola · #10 11-09-2011, 05:40 PM

Don't waste your time and money on adding those elec pumps linked. The MB lift pump wil out pump those puny solenoid pumps 100 to 1. If you add those pumps before the MB lift pump, it will just present itself as a restriction to the MB lift pump and reduce fuel flow, especially at high rpm/ high power demand scenerios.

Biodiesel300TD · #11 11-09-2011, 06:56 PM

Quote:

Originally Posted by funola

Don't waste your time and money on adding those elec pumps linked. The MB lift pump wil out pump those puny solenoid pumps 100 to 1. If you add those pumps before the MB lift pump, it will just present itself as a restriction to the MB lift pump and reduce fuel flow, especially at high rpm/ high power demand scenerios.

I've never had issues with mine. I've never had lack of power issues, other than it being a 240. An aux pump is cheaper than a new lift pump($188 at fastlane)

funola · #12 11-09-2011, 07:34 PM

Quote:

Originally Posted by Biodiesel300TD

I've never had issues with mine. I've never had lack of power issues, other than it being a 240. An aux pump is cheaper than a new lift pump($188 at fastlane)

Did he say his MB lift pump is bad? They are very robust and seldom goes bad. Was yours no good and the reason you added a Facet pump? All that needs to be done to check the lift pump is look up the spec in the FSM for lift pump output and measure volume/ time. You can also measure it with that Facet pump in line before the MB lift pump to see if it helps or hinders fuel delivery. Those solenoid pumps have a disc valve which has very small orifices. I'd be surprised if it helps in any situation, low or high rpm/power.

If he wants to help his single tank wvo (more viscous than diesel) system, he'd be better off removing restrictions by:

1. Ditch the tank strainer
2. Replace the fuel supply and return lines between tank and engine with 1/2" i.d. lines.

Biodiesel300TD · #13 11-09-2011, 09:52 PM

Nope my lift pump is just fine. I should have worded it differently I guess. I was simply saying that rather than put extra stress on the lift pump, which is $188 to replace if it goes bad, $30-$50 of insurance is good.

The MB lift-pump also wasn't designed to pull fluid through a real filter. I put my aux pump above the filter so it would pull the VO through the filter from the tank so the lift-pump didn't have to. This setup with out an aux pump would have had starvation issues. I never had starvation issues, only once when the VO filter was getting clogged.

Those Facet pumps self regulating. Ranging from 2-11.5 PSI depending on demand. How much PSI does the stock lift pump need?

funola · #14 11-09-2011, 10:54 PM

Quote:

Originally Posted by Biodiesel300TD

The MB lift-pump also wasn't designed to pull fluid through a real filter. I put my aux pump above the filter so it would pull the VO through the filter from the tank so the lift-pump didn't have to. This setup with out an aux pump would have had starvation issues. I never had starvation issues, only once when the VO filter was getting clogged.

Those Facet pumps self regulating. Ranging from 2-11.5 PSI depending on demand. How much PSI does the stock lift pump need?

I don't know if the MB lift pump is designed strictly to pull fluid through a filter or not. Though mercedes use it to push fuel through the filter, I have changed it around to pull fuel through the filter. I do not have a helper elec lift pump, the MB lift pump works fine by itself. I have no fuel starvation issues, no air in the fuel lines, just a nice solid stream. All I did was make sure the tank is vented, all unnecessary restrictions removed such as the in tank strainer (I am using the stock tank for VO)

oldsinner111 · #15 11-10-2011, 07:32 AM

I run a pump for alt fuels and diesel.It really pushes the old girl up mountains. Cheaper than a lift pump 12 psi.