Author Topic: adding a fuel lift pump  (Read 581 times)

gusbratz

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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

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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

glort

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Re: adding a fuel lift pump
« Reply #2 on: September 26, 2018, 11:40:49 AM »

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.  Wondering if you guys had any other ideas.

First thing that comes to mind is run one of the electric pulse pumps off a transformer...... or a cheap arse 12V battery charger.  All you need is a 120 to 12V  power supply..... Literally.  Plenty on Fleabay or you could liberate an old computer power supply. Very clean output, way more amps than you'll ever need for a fuel pump, runs off what ever the Voltage is in your area. 
Should be able to find them anywhere cheap as chips if you don't already have one in the treasure Pile.


I have bought 4 of these fuel Pumps in the last couple of months and found them to be great. Used one on the petrol Forklift, one on the wood splitter, one on a Diesel engine and another I have tested for pumping veg for one of my little 100 Kw oil burners.  They work great and are cheap as chips.
Actually had to T off the supply on the forklift as the pump was a bit strong for the carby float. Adding a T with a bit of fencing wire ( nothing it isn't good for!)  in the return as a restriction gave the carb all the supply it could handle but at minimal pressure.



https://www.ebay.com.au/itm/12V-Volt-Petrol-Diesel-HPs-Fuel-Pump-Universal-Inline-Electric-Pump-HEP-02A-Car/283068609928?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

38ac

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Re: adding a fuel lift pump
« Reply #3 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 »
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Barenburg

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Re: adding a fuel lift pump
« Reply #4 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

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Re: adding a fuel lift pump
« Reply #5 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. 

glort

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Re: adding a fuel lift pump
« Reply #6 on: September 27, 2018, 11:15:19 AM »
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.

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.

Lot of ways to do it while meeting every preferred design Criteria.

Quote
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. 

I have done the same thing myself.  Tapped off an air supply with 1/4" hose from the outlet of a blower on a burner to the top of the sealed, gravity feeding fuel tank.  It compensates for the dropping fuel level and keeps a constant flow rate.

I can tell you from wide experience and measurement, A shop vac is not going to provide a couple of PSI.
1/8 to 1/4 PSI would be the upper limit. You need a really well and specifically designed fan to provide pressure. Been trying to get my hands on something that provides a couple of PSI@ 2in diameter for years I could afford.

Shop vac and other fan driven air pumps are very low pressure but it could be all you need depending on the height you need to raise a fluid or if you just want a positive pressure.
In my experience, a plastic 25L Drum is bulging at the seams with 2 PSI and a regular 200L drum is also starting to look noticably stressed. There is a lot of surface area on a drum and the metal is thin and not made to take it.

Just the same, You can get really good fuel flow with just 2 Psi especially if you use a larger diameter hose and neck it down at the end.

38ac

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Re: adding a fuel lift pump
« Reply #7 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.
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ajaffa1

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Re: adding a fuel lift pump
« Reply #8 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

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Re: adding a fuel lift pump
« Reply #9 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

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Re: adding a fuel lift pump
« Reply #10 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.

glort

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Re: adding a fuel lift pump
« Reply #11 on: September 28, 2018, 02:20:20 AM »


They watch every failed policy around the world and manage to propose more expensive failures.............

I thought the United states of Australia specialised in that!

A recent one was Fracking.  Endless evidence of the destruction and problems it causes but it won't happen here because we are going to do it the exact same way that was proven 100 times over to cause the exact same problems everywhere else!
Fortunately they woke up after a few years and banned it but at one stage they were looking to sink wells in parks next to schools in the inner city!
Forget the fact we have enough gas for 1000 years, they just wanted a cheaper way to get what they knew was already there in the outback so the profits would be even higher..... after we sell it to China for  1-3 Cents per litre.  >:(

Much as westerners are programmed to think it's draconian, there IS a lot of good elements in the communist system, even China's.
If you look at some of the GOOD things they have done for their people and they way they are committed to furthering the countries for the benefit of the Citizens with 20 year instead of 3-4 year plans, there are a lot of worthwhile lessons, initiatives and things that would be actually worth the western pollies copying.

Then again while most of here bitch, Look at what Poor Ed has to put up with where he is!

Unfortunately in the west, it's all about making bucks..... without there being any record of that coming back to those in power. 

veggie

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Re: adding a fuel lift pump
« Reply #12 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
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glort

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Re: adding a fuel lift pump
« Reply #13 on: September 29, 2018, 04:27:40 AM »

To the best of my Knowledge, they pull back on a solenoid and push via spring pressure.
If there is a restriction or the fuel is up to pressure, they won't fire again until the pressure drops and allows the plunger to return to the base position at which time the solenoid fires again and more fuel is pumped. Some also part stroke so they do not do a full  but rather a short  stroke.

They are a virtual stop start setup anyway so it makes them useful for burners where the flow can be controlled with a simple on/ off setting timer board.
You are not slowing a motor down, just widening the pulses so the over all flow is reduced.
You could easy do the same thing for an engine but I'm not sure why you would want to. That would reduce flow but not necessarily pressure. Probably OK for pumping to a gravity spill feed or something.

veggie

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Re: adding a fuel lift pump
« Reply #14 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
- Kubota Z482 - 4kw
- JiangDong R165 Air cooled - 2 kw