MEP -002A Fuel Pump Needed, or not?

[Triple Jim]

I doubt if the flow is the full capacity of the pump. It doesn't take much restriction to slow down these impulse type pumps. Just run a test, putting the return into a container so you can measure the flow over a given time, and you'll know the answer. My guess is that the return is a lot more than the engine burns.

 

[Incredilion]

Well the facet pump 480517E flows 33 gph. At full load the MEP-002a burns .5 gph. So you will be dealing with 32.5 gph of return fuel if you used a pump. Gravity feed you will of course have less fuel returning. Most likely your idea won't work. Good luck.

It may not work, I'll check with Onan on Monday & see how much fuel is returned via the return line. I don't think it's anywhere near the 32.5 gallons you said, as that's an open measurement, like Triple Jim said, without any pressure restriction from the filters that that pump is designed to push fuel though. The day tank has a capacity of 6.75 gallons so if the pump was returning 32.5 GPH back to it, it would circulate over a minimum of almost 5 times an hour, or once every 11 or 12 minutes. I don't think it does that, and if it did, and the fuel was hot, I think it would stay hot.

The Lister I have makes 16 HP, at full output, and has a 4 gallon tank, and the tank doesn't get warm, ever. It has a return line, and I checked it today to feel it after a couple of hours running, and it was very lukewarm, just barely enough to sense it.

If I find out that I need to have a tank inside, I can & will. I'll install a smaller tank, maybe a 5 gallon one on a wall or stand or whatever, and fill it form outside through a line, then have the fuel return dump back into it.

 

[rickf]

I like the spec's om your off grid system. I can tell you that the return on my 002 filled a 2 liter bottle in about 3-4 minutes. That was running the stock pumps. My only worry about the gravity setup would be getting enough flow through the pump for lubrication and cooling. If you are breaking even, by that I mean running good with no return flow, then you are getting no cooling. Something else to think about is that you may slowly lose power as the fuel level in the tank drops and you lose static pressure. Of coarse, 600 gallons at .5 gph is 1200 hrs of operation. I would guess it will be filled more often than that. Good luck and keep us updated.

Rick

 

[Incredilion]

I like the spec's om your off grid system. I can tell you that the return on my 002 filled a 2 liter bottle in about 3-4 minutes. That was running the stock pumps. My only worry about the gravity setup would be getting enough flow through the pump for lubrication and cooling. If you are breaking even, by that I mean running good with no return flow, then you are getting no cooling. Something else to think about is that you may slowly lose power as the fuel level in the tank drops and you lose static pressure. Of coarse, 600 gallons at .5 gph is 1200 hrs of operation. I would guess it will be filled more often than that. Good luck and keep us updated.

Rick

Hi Rick,
Thanks a TON for the info on the return, a 2 liter bottle in 2-4 minutes is what, about a gallon every 6 minutes; or 10 GPH, which would still mean I need a sub tank....looking forward to talking w Onan on Monday, that'll be final nail in the coffin....thanks very much-
Chris

 

[storeman]

From the -12:
a. Testing on Equipment. Perform operational test
for each pump individually. Each pump should pump
at 6 to 7 psi as registered on an accurate fuel pressure
gauge. Connect fuel pressure gauge to output
port of pump. Turn master switch to PRIME AND
RUN position. pressure gauge should register 6 to 7
psi.

Unless you provide some pressure approaching 6-7 psi, I suspect insufficient fuel will get to the IP.

 

[edgephoto]

From the -12:
a. Testing on Equipment. Perform operational test
for each pump individually. Each pump should pump
at 6 to 7 psi as registered on an accurate fuel pressure
gauge. Connect fuel pressure gauge to output
port of pump. Turn master switch to PRIME AND
RUN position. pressure gauge should register 6 to 7
psi.

Unless you provide some pressure approaching 6-7 psi, I suspect insufficient fuel will get to the IP.

For gravity feed at 6psi you need to be just about 14 feet in the air. (2.3 feet per psi)

 

[Triple Jim]

That 2.3 feet per psi is for water. It's more like 2.7 feet per psi for diesel fuel.

I don't think the injector pump really needs the full pressure of even one pump to function properly, but as stated, it does need enough pressure to be able to return enough fuel to stay cool, and I have no idea what that pressure is.

Storeman's quote above does imply that the manufacturer wants around 6 psi or more before the filters, assuming the system is designed to run properly if one pump fails. It could be saying that the fuel pump is not working properly if the pressure is lower though, not that the injector pump will suffer below that pressure.

Personally, I'd use a stock type pump in the stock configuration because the pumps aren't very expensive, and they run for years without attention.

 

[Keith_J]

I don't see why the OP is adverse to using a mechanical fuel pump with return line. Even Parflex would be fine here. Probably polypropylene or polyethylene if temperatures are appropriate. A singe Facet pump would work fine given the NPSH afforded by gravity.

 

[edgephoto]

I don't see why the OP is adverse to using a mechanical fuel pump with return line. Even Parflex would be fine here. Probably polypropylene or polyethylene if temperatures are appropriate. A singe Facet pump would work fine given the NPSH afforded by gravity.

Not sure why either. But to each his own.

 

[Incredilion]

Not sure why either. But to each his own.

Guys, I'd like to use gravity purely for it's simplicity, I know that I may end up using a pump, but if I can avoid it I will. I like as few points of failure as possible, I try to do things like this where I can. I have a Lister and a Solar Heat Exchanger that both run on thermosiphon, simplicyt rules for me.
Like I said, on Monday I'll holler at the folks form Onana, and they will probably tell me what some of you are sayng; that I need a pump, and that the return fuel is a lot. I priced a fuel pump (28V) at NAPA, and they wanted somethign like 70 bucks for it. No biggy, but like I said, if I can live w/o it....

Happy Thanksgiving to all of you-
Chris

 

[Incredilion]

OK, spoke with Onan, and here's what they said:
The Injector pump makes all of the pressure needed to return the fuel on the return line for cooling, etc, and as long as it has a steady supply of fuel, it does not need to be pressurized prior to the IP, so no auxiliary pump necessary. The auxiliary pump on the MEP's is for pushing the fuel through the filters, recognizing that military fuel used in the generators may not always be of the best quality, hence the idea of multiple pumps.
On return fuel, he said it will vary between 1 & 5 GPH, depending on the IP.
I'm going to use the Lister tank as a day tank, so it also serves as a return tank.

 

[Triple Jim]

That's valuable information, thanks. It opens up a lot of possibilities for pumpless fuel tank configurations.

 

[Incredilion]

That's valuable information, thanks. It opens up a lot of possibilities for pumpless fuel tank configurations.

Jim, I'm going to hook it up both ways, and see if there's actually any difference in terms of return flow to the tank if I use a pump or if I don't. If there's no difference, than what they told me is absolutely confirmed, but what they said makes a lot of sense. On the civilian version of the engine, they have a cam or gear driven fuel pump, and it's purpose is again to drive fuel through a filter. If I have a tank that's filtering the fuel prior to it getting to the engine, I think I'm pretty well covered.

After I get this set up, in the next couple of weeks or so (GODwilling) I'll report back on the results.

Chris

 

[CNGsaves]

Great thread concerning auxillary fuel source. Would like to do similar gravity feed setup for 55 gallon drum of extra diesel for MEP-002a (typical setup).

Chris your setup is innovative if it all works out. Keep us posted!

 

[rickf]

Looking at Incredilion's sig I can see he would have no issues with this but for you guy's considering a new setup, keep in mind you have to be able to fill that elevated tank.

Rick

 

[Incredilion]

Looking at Incredilion's sig I can see he would have no issues with this but for you guy's considering a new setup, keep in mind you have to be able to fill that elevated tank.

Rick

Naw, Rick, my tankers are for used oil, waste oil/s, I have diesel & gas delivered, so they pump the fuel into the tank/s for me.

 

[edgephoto]

Naw, Rick, my tankers are for used oil, waste oil/s, I have diesel & gas delivered, so they pump the fuel into the tank/s for me.

As long as you don't need a ladder to reach the fill.

 

[Incredilion]

As long as you don't need a ladder to reach the fill.

OK, I don't get it, are you guys against storing fuel or something? We have ladders at my house.

 

[edgephoto]

OK, I don't get it, are you guys against storing fuel or something? We have ladders at my house.

Not against storing fuel. After the October snowstorm last year and Sandy this year stored fuel proved to be a smart thing. I actually gave my fuel to a friend who could not get any. I just not sure I would want my fuel tank 10 feet or more in the air. Maybe in cow country you could get away with that. My town would send me a cease and desist letter pretty quick if I had a fuel tank up in the air. Plus I do not want to climb a ladder to fill my tank or do anything with the tank. Also in 90 mph winds there is a good chance the tower can be damaged, knocked over or hit by a tree. An expensive mess.

I would prefer to have a small drum, 30 gal and use my home heating oil tank for storage. My preparations are for a long outage. I figure last year I lost power for a week and this year 60% of my town lost power for a week again. I am planning to have fuel on hand for a 7-10 days of 12 hr operation. Then I would tap into my home heating oil tank if I could not refill at a fuel station. I am not worried about the end of the world, EMP, foreign invasion or gov't collapse. I don't even have any ammo in my house.

To each his own. We all have different needs and situations.

 

[Incredilion]

Not against storing fuel. After the October snowstorm last year and Sandy this year stored fuel proved to be a smart thing. I actually gave my fuel to a friend who could not get any. I just not sure I would want my fuel tank 10 feet or more in the air. Maybe in cow country you could get away with that. My town would send me a cease and desist letter pretty quick if I had a fuel tank up in the air. Plus I do not want to climb a ladder to fill my tank or do anything with the tank. Also in 90 mph winds there is a good chance the tower can be damaged, knocked over or hit by a tree. An expensive mess.

I would prefer to have a small drum, 30 gal and use my home heating oil tank for storage. My preparations are for a long outage. I figure last year I lost power for a week and this year 60% of my town lost power for a week again. I am planning to have fuel on hand for a 7-10 days of 12 hr operation. Then I would tap into my home heating oil tank if I could not refill at a fuel station. I am not worried about the end of the world, EMP, foreign invasion or gov't collapse. I don't even have any ammo in my house.

To each his own. We all have different needs and situations.

Well, I understand the "to each his own" stuff, I didn't understand why "as long as you don't need a ladder to reach the fill" line.
I live on a mountain, we get big winds, my tank is still relatively protected by my house. I feel for ya if you have to fear that your government would issue you a cease & desist order over a tank, I guess that's why I live "out with the cows" in Idaho. I don't think that a tank that has a bottom 5 or 6 feet off the ground is "up in the air", as people have been using gravity to feed fuel forever. Like you said, to each his own.