Installing an electric fuel pump for WVO - PeachParts Mercedes-Benz Forum

Diesel Dan · #1 09-15-2006, 09:41 PM

I'm putting a Facet electric fuel pump in my 1987 300D to help move the SVO from my veg tank to the veg filter. The instructions say to put it no further than 12" from the tank, so it will push the fuel rather than pull it. The guy at the auto parts store also warned me about this. The problem is that due to the fuel line-in-hose design of the greasecar system, it's not really feasible to put the pump near the tank. I was planning on putting it in the engine compartment right where the pex line emerges at the bottom of the veg filter apparatus copper coolant winding. This, of course, goes against the advice I've gotten so far, but I can't think of another solution. The pump puts out about 5-7 psi continuously (unregulated). Also, I'm not bypassing the lift pump, so the pressurized fuel will be arriving at the lift pump after going through the veg filter, solenoid, and about 2 feet of hose.

Anyone have good or bad experiences to report with locating an electric pump far away from the fuel tank? Using in conjuction with the lift pump? Am I going to break something?

Austin85 · #2 09-16-2006, 01:57 AM

How does the greasecar system, impede the short rubber fuel line just off the tank screen filter? This is what you splice the pump into.

Diesel Dan · #3 09-16-2006, 09:19 AM

Quote:

Originally Posted by Austin85

How does the greasecar system, impede the short rubber fuel line just off the tank screen filter? This is what you splice the pump into.

The greasecar system is a two tank system. I'm not pumping from my normal diesel tank, but rather from a secondary veggie oil tank. When the fuel line comes out of this tank, it is sheathed in a coolant hose. It only emerges from this sheathing at a special adapter on the bottom of the veg filter. There is really no way to put anything in-line until the pex line comes out of the end of the coolant hose sheath.

The only other alternative is an in-tank pump, but I've already sealed my tank, and greasecar saw fit to skimp by not having a real gasket on the tank access hatch, but rather using this silicone RTV gasket maker stuff. So opening the tank access hatch is a real hassle.

Jmana · #4 09-16-2006, 12:00 PM

A Facet pump will work in the engine bay, but I have found that they burn out real quick. The one I had only lasted a couple days. They get really hot to begin with, I guess that combined with the higher viscosity oil, and engine heat burns out the electronics. I ended up just looping the return right after the veg filter, which has eliminated any supply isssues, but has brought up other issues - namely that the 3 port Greasecar valve I bought leaks air and so with a loop the air has no where to go.

Blevinsax · #5 09-16-2006, 12:15 PM

I've experienced similar problems with the veggie fuel line in the GreaseCar system in my '91 350SD, too. I read about the facet pumps burning out - and my mechanic told me that he tried other pumps on another car's GreaseCar system and they all burned out in a matter of hours, so he recommended getting the pump made my GreaseCar. Unfortunately it is $115, but it is designed to pump WVO so it won't burn out. I already bought one and had it installed, but it also exposed a problem with one of the valves. One of the valves is defective and although I know that I am running on WVO (I know because the exhaust smells just like burgers on the grill!) it seems clear that the valve is allowing some diesel (as well as air) into the mix because my diesel fuel gauge is dropping along with my WVO gauge! I've already spoken with the folks at GreaseCar and they have sent me a new valve and switch - at no cost, provided I send back the defective part. It should arrive today or Monday (hopefully - takes a while for stuff to make it to Vegas) so I will have it checked out and hopefully fixed very early next week.

Long story short, I bought the pump from GreaseCar, but it did not resolve my fuel supply problem.

Diesel Dan · #6 09-19-2006, 09:56 AM

Anyone have recommendations for a good in-tank pump that could withstand the heat of a heated veggie fuel tank, and not get destroyed by biodiesel returned fuel?

Also, if the pump is active, and the return fuel is supposed to go back to the tank through the supply line, what happens with the return circuit? The active pump would prevent the return fuel from going anywhere. I assume it gets looped back to the injectors, or the return circuit would just be essentially eliminated. Would this create a problem? I have to confess, I really don't understand the whole "return fuel" concept very well. I'm a diesel newbie.

Diesel Dan · #7 10-19-2006, 11:27 PM

Well, the Facet electric fuel pump I had in my engine bay died today after pumping about 20 gallons of WVO. Looks like it's back to the drawing board. Has anyone had any success with other fuel pump brands? I'm thinking at this point that I've got to find a way to locate the pump right next to the fuel tank, or get an "in-tank" pump. I think the in-tank pump would be the cleanest installation, but I worry about the heat of the WVO burning out the pump.

I've thought of a way to work around the Greasecar system, and install an electric in-line pump right on top of the veggie tank on the outside of the tank, so that the fuel line pulls fuel out of the tank and then pumps it back into the pex line on the inside of the tank where it comes in from the front. Its kind of an awkward setup though. But, from what I understand, these pumps are supposed to be located no more than 12" from the tank, so they "push" the fuel, rather than "pulling" it all the way from the front of the car. I suppose it would be even better if I could locate it outside the trunk, on the underside of the car, so it gets more air circulation.

Does anyone have any experience using an in-tank electric fuel pump in a heated WVO tank?

pgringo · #8 10-20-2006, 12:10 AM

Quote:

Originally Posted by Diesel Dan

and greasecar saw fit to skimp by not having a real gasket on the tank access hatch, but rather using this silicone RTV gasket maker stuff. So opening the tank access hatch is a real hassle.

go to a napa and buy a piece of gasket material. tell them what it will be used for and they should know what type of stuff to sell you.

greetings from san marcos, just south of you.

Blevinsax · #9 10-20-2006, 01:41 AM

I ordered and installed the fuel pump from GreaseCar - it is still running, works fine, and I've had no problems. It's kind of expensive, but it does work.

Addicted · #10 10-20-2006, 07:41 AM

Holley Blue/Red

I've heard these hold up well/not heard of one giving out. I have not replaced mine yet. My faucet burned out after about 2-3 hundred gallons. Only reason it lasted that long was my oil going through it never got that hot and was heated by an element afterwards and it was open to the air undernieth the cab of my truck to keep it cool. i think ou can find these new for around 60 or so.

Diesel Dan · #11 10-20-2006, 02:39 PM

Even the Holley pumps are supposed to be mounted within a short distance of the fuel tank, and they need to be gravity-fed (ie: below the level of the bottom of the tank). With the greasecar veg tank being located in the spare tire spot it's pretty hard to mount the fuel pump any lower than that without risking ground clearance issues.

Right now I'm researching a new line of "Walbro" in-line pumps which may offer some more flexibility regarding placement. They are also specifically designed to handle diesel and biodiesel fuels, whereas Holley is supposed to be for gasoline only. I'm waiting for an answer from Walbro about the location issue, and keeping my fingers crossed. But still, it's only rated to 155 degrees fahrenheit, so that could become an issue with heat burnout.

The in-tank pumps won't work because they need to be mounted vertically, and the Greasecar tank is only 7" tall. These pumps are usually at least 6", plus the hose nipple clearance needed. I wonder if they could be mounted at an angle? But of course you have the heat issue coming up again...

biopete · #12 10-20-2006, 03:05 PM

Why the extra lift pump? Is it to save stock one from extra wear?
Does the stock one not pull enough grease?

thanks

WD8CDH · #13 10-20-2006, 04:36 PM

Personally, I use the stock lift pump for diesel and an aux electric lift pump for veggie. With seperate lift pumps, switchover and purge is quicker.

#14 10-20-2006, 06:03 PM

I've used the Walbro Gerotor in-line pump. It has no problem at all pumping veggie. The only problem is that it doesn't have a pressure bypass valve, so you will need to get that seperately. Otherwise, it will boost the pressure up until something pops. Matt300SD has a metal body Facet which he swears by.

Diesel Dan · #15 10-20-2006, 10:19 PM

Quote:

Originally Posted by biopete

Why the extra lift pump? Is it to save stock one from extra wear?
Does the stock one not pull enough grease?

thanks

From what I've heard, the 124 type Mercedes normally requires some kind of gravity assist to get the diesel fuel to the lift pump. So when you put in a greasecar kit with the tank in the spare tire area, the LP is not able to pull the oil since the tank is lower than the LP. Apparently the older 123 models don't have this issue. Lucky you! Having said that though, some 123 owners have installed these pumps anyway. Sometimes I think it acts as a crutch to overcome air leakage problems, or maybe just an old/weak LP.