Author Topic: adding a fuel lift pump  (Read 3887 times)

gusbratz

  • Jr. Member
  • **
  • Posts: 91
    • View Profile
adding a fuel lift pump
« on: September 26, 2018, 11:07:10 AM »
 I want to convert my DES 8-1  homemade generator to run off the 100 gallon bulk tank that sits on the other side of the wall on the ground (lower than the engine).  This will allow me to eliminate the fuel tank I have inside the generator shed.  The problem is I will need a fuel lift pump. the first thing that comes to mind is the little 12v pulse pumps I have used on stuff for years, the problem is I don't have 12v on my generator shed nor do I want to add a battery and charging stuff. I couldn't find any of them in a 120V rating so I gave up on that. then I thought what about  the cheesy little diaphragm pumps kohler and briggs use on their engines that pulse off the crank case. I could drill  a hole in the cover and screw it on and It should pulse.  Wondering if you guys had any other ideas.

ajaffa1

  • Hero Member
  • *****
  • Posts: 1725
    • View Profile
Re: adding a fuel lift pump
« Reply #1 on: September 26, 2018, 11:16:18 AM »
Hi Gasbratz, first question has to be: how much lower? The small diagram pumps you are considering are only good for about half a meter, max. If you want total reliability without mechanical/electrical failure points raise the tank and gravity feed.

Bob

38ac

  • Hero Member
  • *****
  • Posts: 2324
    • View Profile
Re: adding a fuel lift pump
« Reply #2 on: September 26, 2018, 12:53:18 PM »
The original recommendations were for a gravity fed day tank which can be filled by any one of several means from other storage.

  That being said any pressure feed system you devise must consider that the fuel pump moves the exact same amount of fuel each stroke. What changes is how much goes to the injector and how much is pushed back the inlet line. Those clicker type pumps use valves that do not allow reverse flow. Thus you must provide a means for the fuel to go backwards in the line. This can be as simple as a length of rubber hose. What you cannot ( or more exactly should not) do is hard plumb the entire distance between the two pumps. Sure as hell I say that someone will say WTF?? I did it??  I did not say it will blow the pump to smithereens the first stroke but common sense says that if the pump must expand ridged tubing that the stress on the pump element, rack, cam and push rod is all dramatically increased not to mention what it is doing to the fuel pump valving.  Secondly the pumps were just plain not designed to have large amounts of head pushing fuel to them. Any internal leaks at the element will be increased as head increases. You want the least amount of head pushing on the injection pump that will provide the needed fuel.  Every one I know who has gone this route with work engines that run daily has reverted back to gravity feed,,,,
« Last Edit: September 26, 2018, 02:47:03 PM by 38ac »
Collector and horder of about anything diesel

Barenburg

  • Newbie
  • *
  • Posts: 26
    • View Profile
Re: adding a fuel lift pump
« Reply #3 on: September 26, 2018, 04:19:52 PM »
Personally I like the vacuum-pules pumps in line with a primer bulb.  They work off of the pressure changes in the crankcase.  I've used them for up to about a 1 meter lift.

gusbratz

  • Jr. Member
  • **
  • Posts: 91
    • View Profile
Re: adding a fuel lift pump
« Reply #4 on: September 27, 2018, 07:28:10 AM »
I like the squeeze bulb idea, It is nice to be able to move some fuel to bleed the system out after maintenance.  one idea I have used in the past is to take the exhaust hose on the shop vac and stuff it into the tank filler with a rag around it. the shop vac will pressurize the tank with a couple psi and you can bleed everything out real nice. 

38ac

  • Hero Member
  • *****
  • Posts: 2324
    • View Profile
Re: adding a fuel lift pump
« Reply #5 on: September 27, 2018, 12:06:26 PM »

Which would make T'ing the line so it provides flow with little pressure a good idea in this application as well.

You connect the input and output of the pump together.  You can put a valve or otherwise restrict the connection between the 2 so there is positive flow but little pressure.  You can put the pump near the engine drawing from the tank.  Near the injector pump, you put the T Fitting and have the supply to the engine off the other branch.  This will pull the fuel from the tank giving the engine all the fuel it wants and returns the excess to the inlet side on the pump which will reduce the load on it.

You could also have the pump lifting to a gravity tank with an over flow back to the inlet side again so the pump  keeps a constant level on the tank. Could also use the pump to pull up the fuel to fill a day tank located near and above the engine. Add a cheap level switch and it will auto fill when it needs to.



Yes any of that would work.  It would also provide for easy bleeding of the fuel system up to the overflow point.
Collector and horder of about anything diesel

ajaffa1

  • Hero Member
  • *****
  • Posts: 1725
    • View Profile
Re: adding a fuel lift pump
« Reply #6 on: September 27, 2018, 01:54:06 PM »
Hi Gusbratz, there has been a lot of discussion around this issue over the years. I`m with 38ac, keep it simple, raise the tank.
I`m old and have been around for a long time, the only things that have never changed in my lifetime are gravity and how stupid the politicians are. If I had to put money on one of the two I`d chose gravity every time.  :)

If anyone knows how to install a hot air and bull sh1t collector in Canberra, Australia we can probably solve the world energy crisis.

Bob

Barenburg

  • Newbie
  • *
  • Posts: 26
    • View Profile
Re: adding a fuel lift pump
« Reply #7 on: September 27, 2018, 03:23:11 PM »
Hi Gusbratz, there has been a lot of discussion around this issue over the years. I`m with 38ac, keep it simple, raise the tank.
I`m old and have been around for a long time, the only things that have never changed in my lifetime are gravity and how stupid the politicians are. If I had to put money on one of the two I`d chose gravity every time.  :)

If anyone knows how to install a hot air and bull sh1t collector in Canberra, Australia we can probably solve the world energy crisis.

Bob

Bob, it never ceases to amaze me how politicians here in the USA get stupid-er every year.  They watch every failed policy around the world and manage to propose more expensive failures.............

broncodriver99

  • Sr. Member
  • ****
  • Posts: 477
    • View Profile
Re: adding a fuel lift pump
« Reply #8 on: September 27, 2018, 09:57:22 PM »
Bob, it never ceases to amaze me how politicians here in the USA get stupid-er every year.  They watch every failed policy around the world and manage to propose more expensive failures.............

It would definitely help if we would stop electing Morons. Then again no sane/intelligent person runs for office.

veggie

  • Keep Calm and Start the Lister !
  • Hero Member
  • *****
  • Posts: 843
    • View Profile
Re: adding a fuel lift pump
« Reply #9 on: September 28, 2018, 04:25:34 PM »
Glort,

Regarding that 12 volt fuel pump that you pictured above ... does it shut off when the pressure builds too high? or does is simply stall if there is a restriction like a closed valve?

Just wondering if it needs a bypass back to suction so that it doesn't stall.

cheers,
veggie
« Last Edit: September 28, 2018, 05:47:00 PM by veggie »
- 6/1 GM90 Listeroid - Delco 33si Alternator
- Changfa R175 - Lease/Neville Alternator
- JiangDong R165 Air cooled - 2 kw
- Changfa S195 (Waiting for a project)

veggie

  • Keep Calm and Start the Lister !
  • Hero Member
  • *****
  • Posts: 843
    • View Profile
Re: adding a fuel lift pump
« Reply #10 on: September 30, 2018, 02:25:53 AM »

So... if a person fed the IP of a listeroid with this pump...and the pump flow rate is greater than the Roid is using, the pump will automatically adjust?

Veggie
- 6/1 GM90 Listeroid - Delco 33si Alternator
- Changfa R175 - Lease/Neville Alternator
- JiangDong R165 Air cooled - 2 kw
- Changfa S195 (Waiting for a project)

dieselspanner

  • Hero Member
  • *****
  • Posts: 726
    • View Profile
Re: adding a fuel lift pump
« Reply #11 on: September 30, 2018, 08:33:32 AM »
Yes, but the pressure may well be higher than the IP would like / tolerate, hence the the idea of putting a tee in the line to recirculate the fuel constantly and to allow the IP to 'back pressure the inlet without restriction.

Cheers
Stef
Tighten 'til it strips, weld nut to chassis, peen stud, adjust with angle grinder.

38ac

  • Hero Member
  • *****
  • Posts: 2324
    • View Profile
Re: adding a fuel lift pump
« Reply #12 on: October 02, 2018, 02:03:59 PM »

 I never said that inlet pressure provided by an external pump as pictured would stress or harm the IP.  I said it would cause what ever internal leaks it has to be magnified,  which is true.  I did say that  the excess fuel pumped  back the inlet line by the injection pump must have a place to go, this is nothing but common sense, no manual needed. Given ridged plumbing between the IP and  supply pump and  the one way discharge valve present in every  clicker type pump there would be no guessing that high pressures will be created and additional stress on the pump and drive components would be created. You may also notice that I also gave room for you and the rest of the "WTF I did it?" crowd by stating it would not cause the pump to self destruct on cycle#1.  The china diesel fuel injection system is operationally identical to a Listeroid.  Did you connect your pumps with a rubber hose? if so I also allowed  that a hose  would created the expansion area needed between the two pumps.


Please be accurate when you  quote me as to point out error in my advise  be it factual, perceived, implied, guessed at or otherwise .

Do as you please if it works good enough to cause you to smile then have at it  ;)
« Last Edit: October 02, 2018, 02:06:12 PM by 38ac »
Collector and horder of about anything diesel