Fuel Line Primer Pumps

[Crofter]

Hi Frank,

I checked at Princess and Northern Tool (re-directed by google) and no bunghole flanges.  I'm gonna find it pretty hard to pass on bunghole flanges.  Do they provide for an internal dip pipe going near the bottom of the tank?  I like the mechanically enlarged hole so the lip provides more brass area.  My plan was to use a 90 with a 12 inch nipple going down inside for pick-up.

I can get pretty loose around a torch - thanks for the reminder.  With a 3 inch hole in the top for a week or two I'm not too worried about an unplanned  rush.   

Casey

I know bunghole is not the term used in the catalogue but the item provides a pipe thread opening in medium weight sheeet metal which is much easier to braze onto tanks than the greater mass of a pipe coupling. You can use a drop tube as a fuel pickup but it will not gravity feed unless you create a siphon but I dont have a picture of you layout or pump arrangement. It is not a likely thing but a long unsupported drop tube can break inside from vibration and give you a bit of consternation while you figure out why that tank is full but you get no fuel 

[LowGear]

Hi Ron,

We already knew that.

Thank-you,

Casey

[LowGear]

Hi bschwartz,

Yeah, most things in my life are uphill.  The Witte has a fuel pump - see photo.  I left the this fuel tank back in Seattle.  For the next few years I expect to set the tank on the floor.  This might sound funny but I hate to lift fuel cans above my waist.  One of the reasons I went for a Kubota tractor over a Deere was the ease of filling the fuel tank.

This does segue into the next question:  If I put a float valve on the fuel line so that when the tank nears empty it closes off the line and the engine stops from lack of fuel will I need to prime the line and the injector or will it just stop and leave fuel in the line.  There is a difference in the next time the engine is ran - right?

Segue Part II:  Anyone know of a fuel filter that I could put in-line right next to the pump, maybe even thread right into the pump?  I'm not looking for one of those one quart one micron units but at the same time I want something better than the lawn mower filter that is on the line now.  Screw-on cartridges are so wonderful don't you agree?

Casey

[Tom Reed]

Casey, If you go this route I think you'll be spending a lot of time bleeding air out of the system. Why not make a raised gravity feed day tank and setup a transfer pump, with a filter, to fill it from a container on the ground. That is my plan. With a clear filter you can monitor the fuel quality as it is pumped.

[bschwartz]

You could rig a float switch that engages/disengages electrically a decompressor solenoid.  That way it would shut off the engine on a low fuel situation without sucking air into the lines.

[LowGear]

Hi,

I was under the impression that the way most diesels stop is that the fuel supply is cut-off?  A mechanism that would move the compression lever to the off position sounds complicated to me.

I don't see the difference between stopping fuel being sucked up by a fuel pump or a gravity line running out of fuel.  I'm thinking the float valve will stop the line from being filled with air.  I can be pretty bull headed when I get a design stuck in my head.  What am I missing?

The good news is that I'm going ahead with the outboard fuel supply line that has the hand pump built in.  You've convinced me I should be able to assess if it's going down hill and presents a threat of fuel all over the blasted place before it happens.

Casey

[bschwartz]

Casey,

Fuel injection pumps are really good at their job.  They suck in fuel and force it under pressure to the injector/s.
My experience shows that they will draw a bit of suction if fuel isn't readily available (clogged fuel line).  Where there is vacuum, something wants to fill the void.  Fuel would be best, but barring that, air will do.  If your fuel lines are perfectly sealed, shutting off the fuel at the tank will ultimately shut the engine off, but a vacuum WILL be drawn into the entire line.  Any minor leaks WILL be found, and air sucked in.

Consider this fair warning before going to the trouble of building it only to find yourself repriming the system on a regular basis.

-Brett

[slowspeed]

Casey
If you could do a gravity feed
think about mounting a white plastic 50 gal, drum (drum #1)or bigger,Over head
You could get your oil from your oil supplier, pump it in to the 50 gal. let that drop into your cleaning device
I use a centrifuge,
Out of your clean drum (drum #2) have a line feeding the witte? and your shop heater that you may want to run on WVO
The plastic can be seen thru drum #1
no brazing just drill and tap
jeff
AZ

[vdubnut62]

Casey, injector pumps DO shut off the fuel ... by closing the rack to stop the fuel.  Injector pumps DO NOT like to be forced to pull a vacuum, it can cause permanent damage.  Ask some one who owns a 99 or later Dodge/Cummins and had the lift pump fail. I imagine that replacement pumps are quite pricey for your old and fairly rare engine.
Ron

[LowGear]

Geezzzzz,

I hate being so ignorant!  OK, What's the injector rack?

This engine is fitted with a factory lift pump.  And diesel guy got me to buy a replacement while they're still available but I don't want to intentionally cause problems.  I'll go out and take some pictures of the fail-safe mechanism and maybe we can figure a smart (Simple) way to shut this puppy down when it gets low on fuel.  My plan is to set it up for a run and go about my merry business and not have to worry about it until the next time I feel like helping the local utility.  Rockey Jones Space Cadet reporting for duty, Sir!

You're getting me there.  I do appreciate the interest and education.

Casey

[vdubnut62]

Casey, injector pumps DO shut off the fuel ... by closing the rack to stop the fuel.  Injector pumps DO NOT like to be forced to pull a vacuum, it can cause permanent damage.  Ask some one who owns a 99 or later Dodge/Cummins and had the lift pump fail. I imagine that replacement pumps are quite pricey for your old and fairly rare engine.
Ron

Sorry I didn't make the above very clear, insert "injector" after the word replacement.
The rack changes the amount of fuel that the injector pump squirts into the injector, from none to full throttle.
Ron

[flywheel]

Casey

I can guarantee you that if you shut your diesel engine off by starving it of fuel, (same as running out of fuel) you will spend more time trying to bleed the air out and getting the engine running again that you will change your mind in hurry.

If you want to spend hours getting it going again go ahead and starve it out.  If you have never had to restart a fuel starved diesel the job can be very intimidating for first timers. 

I'm sure you have read some of the posts on the forum about fuel starved engines due to suction air leaks, clogged filters etc.

The diesel engine is very fussy when it comes to air in the fuel system.

Anyone else care to add anything??

                                                               flywheel

[cgwymp]

Casey,

Fuel injection pumps are really good at their job.  They suck in fuel and force it under pressure to the injector/s.
My experience shows that they will draw a bit of suction if fuel isn't readily available (clogged fuel line). 

I used to work at a MB dealership, and occasionally we'd get in a 300D or 300SD that mud daubers had built a nest in the fuel tank vent line. It was easy to spot what the trouble was because the steel fuel tank would be sucked flat....

Just thought I'd throw that in....  ;-)

[Crofter]

Some fuel injection pumps include a supply pump section that may be gear or vane. It will lift fuel to feed the high pressure injection pump. Some injector pumps have no lift capacity. When you shut a diesel down it is by putting the pump into a zero fuel delivery mode. This will be done by moving the rack and helix or the swashplate or some other similar function within the high pressure section.That is not accomplished by shutting off its fuel supply. Never! When a high pressure injector pump is subject to fuel restriction it will pull a vacuum all right but it subjects it to cavitation damage. This is what Vdub refers to in the cummins losing its supply pump. Do a google on cavitation damage. You might get away with it for a while but starving the fuel supply  is definitely only an emergency shut down measure.

Aside from the very real potential for pump damage the shut down event will be slow and stuttering meanwhile the high pressure part of the injector pump will be forced wide open by the governor.  As Jens mentioned the pump will then be pulling a vacuum and attempting over time to relieve that by having air sneak in around pump shaft or plunger or even back via the injector. Remember that for the most part only close mechanical fit exists between parts with the intention of a minute amount of bypass existing. You will have problems with air. The old disclaimer your mileage may vary holds true but overall the odds are against it being trouble free.

[lowspeedlife]

Casey, the "rack" is usually a rod that passes thru the injection pump that has the govenor linkage connected to it.  when the govenor tries to speed the engine up it pushes (or pulls, depending on the application) the rack . the rack has little gear teeth on it , & meshes with the fuel delivery valve that also has teeth on it. as the rack moves it rotates the valve & that either increases or decreases the amount of fuel delivered to the injector.

   Scott R.