2-stage filter losing prime

[Jay L]

Hi All,

I have a hardy 2-stage filter on a 30 gallon drum for my kubota d1005 generator and after sitting between run-ups, the first filter partially siphons back to the drum.  I have a pump bulb after the filters but it doesn't have enough suction to re-prime the filters - even when I disconnect the supply line from the generator.

Needless to say, if the first filter is full or near-full, the generator runs for about 10 minutes and then quits when it sucks air.  The genny's running suction doesn't fill the filter back up either, even if I pump the bulb.

To make sure it wasn't sucking any air, I did a complete leakdown test all the way to the generator and it holds rock solid, so I have no idea why it's doing this.

It's a REAL pain to re-prime the filters!  I have to take the supply line off the generator and use a pump to get the filters full again.

I thought gravity feed for the whole fuel system would be fine, but maybe I need a lift pump or a check valve or other - any ideas?  And is this a typical problem?

I included a couple of pictures, you can see the second fuel filter seems to stay nearly full, just the first water-block filter is siphoning back to the tank.

[vdubnut62]

You absolutely have to have an air leak someplace! My bet is the close nipple between the filters, or a crack in one of the housings.
Ron.

[Jay L]

Thanks Ron, I hope I can find it when I dig into it again tomorrow.  One piece I didn't check is just out of the picture - I have quick disconnects before the 2" drum  bung on the supply and return lines so I can easily refuel.  They're those Motion Pro jobbies with buna-n o-rings, supposed to be high quality and seem fine but you never know.  Nothing leaks fuel while running or sitting, so you could be right about an air leak on the close nipple even though it didn't show up when I leak-tested it.  I don't think it's the bowls though, they're new and perfect including their seals...  I'll post again after more checks.

[mobile_bob]

fuel system air leaks are the bane of the diesel mechanic, sometimes you can spend hours trying to
find such a leak,

process of elimination will lead you there

remember what leaks under a vacuum may not leak under pressure
and what leaks sitting may not leak sufficiently to notice while running.

some heavy duty trucks are so bad about this problem that any air in the system will keep them
from starting, and what i mean by "any" is just that,,, even just a teaspoon of air can cause a no start problem.

btw, i suspect the quick connects, so i would bypass them first.
also air that is trapped in the top of a filter head, or other high spot might well allow the engine to run
but upon restart cause an issue. i have seen system such a bit of air and still seem to run fine, only to rear
their ugly head and keep an engine from restarting when the air bubble backs out into the system somewhere or finds it way to the injection pump

bob g

[mobile_bob]

having gone back and looked at the pictures, i think Ron is on the problem
check that close nipple and the housings to see if it is getting air there!

with the first filter full, and the second very low, i would think that everything up to the first
filtre is ok, and something past there is the issue.

actually thinking about it, take a look past the second filter because if you have any air getting pulled
back into the system there, it will pull that second filter down a bit on fuel.

if the engine has a lift pump it might have a leak there, or any of the fitting, hoses etc would be suspect to me.

if you have one of those little mityvac hand pumps, you can vacuum test each segment of the system and generally find the problem. harbor freight sells a moderate priced mityvac hand pump so you can get one there if you don't have one.

bob g

[Henry W]

Another thing to look at is the Kubota fuel pump on the D1005 engine could have a pin hole in the diaphram.

I could be wrong here, but I think I also remember reading some place that these fuel pumps are designed to lift fuel up to around 20 inches.

One thing that I would recommend is to install a flow check on the bottom of the suction tube in the tank along with a type of sock or screen to prevent large debre getting sucked in the flow check.


Henry

[Jay L]

Thanks for all your advice...

Going out to figure it out in a few mins...

Question, if I find and stop any air leak that may be causing the problem, do you think the squeeze bulb has enough suction to completely fill the filters?  Just wondering if it's capable of forcing any air back into the drum?  Not sure how it's really supposed to work - I know it can't really push the fuel forward towards the generator, so I'm hoping it's capable of driving air back to the drum - otherwise it's a REAL pain in the neck to fill the filters completely - assume I have to remove the supply line from the generator and pump it from there, but that means I'll likely get a small amount of air back in the supply line when I go to hook it back up to the fuel filter on the generator - ugh!

Again, appreciate all the advice, hopefully I detect an air leak!

Jay L.

[Jay L]

So...  I took everything apart again and just to be sure I redid the teflon tape seal on the close nipple between the filters even though I'm virtually positive that nothing was sucking any air.  I also re-sealed the pickup tube in the 2" bung even though that held air when I pumped it down with a vacuum pump.

I used every method I could think of to refill the filter bowls, but I couldn't get either one to the top even with a fuel pump with its output going back into the drum return line.

I cranked it up and got the filter closest to the generator to fill up completely by working the squeeze bulb and it stays running now.  However, the water block filter closest to the tank will not fill up no matter what I try.  I did a whole bunch of googling and found others with the same issues, and one post said that it filled up over time, not sure how or why.

Attached a new picture so everyone on that's been trying to help can see which end of the setup the generator is on - it's to the left beyond the squeeze bulb.

I'm not sure if the filter will stay full, keeping an eye on it and I'll let you all know.  Anyone have any more ideas?  One thing for sure is that I can't find any air leaks after two days of disassembly and resealing things that were fine all along :-(.

Thanks!
Jay L.

[mobile_bob]

parker makes an inverted bowl system that is used on heavy trucks (some) and it doesn't fill up
in normal operation, you service the element when the bowl finally fills up.  apparently the restriction
of a slowly clogging element pulls more fuel higher into the upside down bowl to get to cleaner element
and continue until there is no clean element left.

maybe these work the same way? i dunno

does the engine refuse to start when the fuel is low in the bowl?

sometime you will find an air problem child that will absolutely drive you crazy to sort out.

not being one to start changing parts, sometimes it is the only recourse one has to get it sorted out.

even then you can be met with gremlins

case in point, a customer i once had, was working on a rear tail light assembly on a chevy van
he replaced the bulb, no work
he cleaned the socket, no work
he removed and replaced the whole assembly, no work
he checked the harness, hmmm that works
he goes to dealer and gets new light assembly, no work
he goes back and gets another assembly from dealer,, waaalaaa it works!
he removes it to recheck the two prior assemblies, no work
put in the last one and it works!

days like that are no fun at all, especially for a diy'er using his own money to fix a problem with replacement parts, which the seller will never believe are anything but perfect when he sold them to you.

bob g

[mobile_bob]

btw
i have seen over the years, brand new parts suck air or leak under a vacuum
everything from new hoses with pin holes, delaminations, cracks etc, fittings with bad threads and sometimes even cracks , cracked or warped filter housings, leaking oring lands and/or orings, leaking check valves in the transfer/lift pump, leaking suction tubes due to cracks, bad solder jobs, pin holes etc. leaking front seals in the injection pump, everything can be suspect and just because it is new is no guarantee it is not the problem.

bob g

[Thob]

Have you checked to be sure the fuel is flowing the proper direction thru the filters?  I don't see any arrows on the filter heads.  The few filters I've had experience with flow from the outside of the filter toward the inside - yours may be different.  Although I keep telling myself that wouldn't matter to your problem, it is something to check.

Is the supply drum vented?  Your not pulling a vacuum on the drum as you use fuel, are you?

Is there a way you can raise the supply drum above the filters so that siphon action from the drum will ensure that the filters are under pressure instead of vacuum?  Maybe even take a smaller fuel can (~5 gal or so) and set it above the filters for a test?  If there's a small leak it might show up after a while if the diesel leaks out.

By the way, that is a nice looking filter setup!  I love those clear bowls so you can see what's inside.

[Jay L]

Hi Bob, I hear you new parts with defects, see it all the time in the IT industry!  Luckily this is an awesome little generator and it never got any air near the injector pump or nozzles, so it has always hard-started back up during this troubleshooting...  Never more than 10-15 second and it fires back up.  Since I found others with the same unfilled bowl issues, it could be normal, but it doesn't instill confidence!  At least with the second filter totally full I think it's in better shape, going to watch it until I exercise it again in a couple/few weeks.  Then I'll know one way or the other if I need to do more frustrating troubleshooting...  Thanks!  Jay L in Hawaii :-).

[Jay L]

Thob,

yes, correct direction - the goldenrod top housings have IN/OUT marked on them :-)

and yes, the drum is vented with 3/4" black pipe - definitely no vacuum happening - you can see the vent pipe in the second picture in the original post - goes through a little notch in the shelf I added afterwards, hehehe.

the drum is actually 1/2 full right now, 15 gallons - I purposely didn't want to fill it the rest of the way until this is sorted out because from every other picture and post I've seen and read, it's typical to mount these filters on the drum edge - in fact, it's a kit from Hardy Diesel and it came with hardware to do so, although I made my own instead.

since i ended up getting the filter closest to the genny completely full, i'm going to wait and see if the level drops over the next couple of weeks - if it does, I'll try putting a 5 gal can above like you suggest - I agree that i should actually see a fuel leak at the filters if it's still sucking air in its current position.

thanks!  i spent a lot of time planning this installation - the whole deal is housed in an Arrow 8' x 3 1/2' metal shed and it all fits great - including space for my air compressor between the drum and the generator, cool stuff!  The generator is anchored to the concrete pad through the exterior 5/8" ply flooring, and it has an automatic 24" intake vent from nooutage.com, an 18" gravity exhaust vent in front of the radiator, and it's grounded/bonded everywhere with #6 thhn and an 8' rod...  I also used a waterproof battery tender through an ELK 912 relay that turns off battery charging while the key is on.  Also put in a new commercial/generator sub panel with mechanically interlocked main/gen breakers, and a powermeter pro outside at the panel so I can manage the load without going in the shed to look at guages on the generator (it actually only has an hour meter, lol), really cool stuff!.  yep, it's ready for the zombie apocalypse! :-)  I'll try to get some more pictures up in another thread when I get some time...

Jay L.

[Lloyd]

So...  I took everything apart again and just to be sure I redid the teflon tape seal on the close nipple between the filters

This has nothing to do with the air leak probable , but never use tef..tape on a fuel system.

One little iota of tef.. is a disaster to an injector pump.

Lloyd

Thanks for all your advice...

Going out to figure it out in a few mins...

Question, if I find and stop any air leak that may be causing the problem, do you think the squeeze bulb has enough suction to completely fill the filters?  Just wondering if it's capable of forcing any air back into the drum?  Not sure how it's really supposed to work - I know it can't really push the fuel forward towards the generator, so I'm hoping it's capable of driving air back to the drum - otherwise it's a REAL pain in the neck to fill the filters completely - assume I have to remove the supply line from the generator and pump it from there, but that means I'll likely get a small amount of air back in the supply line when I go to hook it back up to the fuel filter on the generator - ugh!

Again, appreciate all the advice, hopefully I detect an air leak!

Jay L.

[vdubnut62]

Goldenrod filters are designed to be used on the pressure side of a hand pump used to fill smaller fuel tanks from a bulk tank, if I'm not mistaken.
I'm not saying that they aren't a killer filter system, and won't work in your application, but with no air bleeds on 'em you will probably never get all the air out of the housings, especially if you have them on the vacuum side of your fuel system.
If I read all this wrong, then as Miss Emily Litella on SNL used to say "Never mind".
Ron.