Well it finally got cold enough today to allow running up the engine and heating up the hot water storage tanks. Everything worked just fine for a while .... then I see the engine is belching black smoke. I was not impressed :( After a bit of checking I found out that cylinder #2 was not firing and the load I was running was borderline on the single cylinder.
I loosened the high pressure line at the injector but not much happened. Eventually (maybe 10 minutes of running on one cylinder) the loose connector started to leak fuel and I tightened her up. Shortly afterwards cylinder #2 started firing again.
Ok, I say to myself, probably some fluke ..... everything worked just fine for maybe another half hour and then the same thing happens.
The way I look at it is as follows: Possibility #1 is that there is an air leak in the low pressure feed to the injector pump of cylinder #2. Possibility #2 is that the injector pump itself is defective.
I have had some problems with air getting into the #2 line before when the fuel filter got clogged but in this case I don't think the filter is too clogged yet - it still flows fuel with only a tiny bit of negative pressure.
Is there an easy method of testing for a leak ? There is no fluid leaking out of the steel pipe. It is still the original pipe.
When people replace their fuel system, what is normally used product - steel pipe, rubber fuel hose ? anything else ????
The setup is a bit more complicated because there is a T in the line where the fuel flow is split between the two injector pumps.
Thoughts ?
Jens
is it possible for the pump plunger to be sticking?
or the delivery valve not seating?
might want to pull the pump, take it apart and look it over
real good, just in case a bit of crap is sticking it, before it has
a chance to grind it up.
always something isn't it?
bob g
Hello Jens,
Hope you get it working soon. A few good things is if you have an injector pump problem it is pretty simple to service them. And if you need another, they are inexpensive. It is starting to cool down up north. Stay warm.
Henry
Talk to JohnF, he has lots of experience with twins. Sounds like your getting an air leak somewheres
ah!!!!
the little known "Jens rules of fluid dynamics"
which is closely related to "Jens rule of coupler dynamics"
which are both under the heading
"Murphys Law"
did you get it all cleaned up?
admin
Jens;
Have a look at my website under "new gen shed" You should see a pic of my fuel setup which shows three fuel lines running from separate tanks into a 3 - 1 brass fitting (it is actually an air hose fitting) then into the I.P. Each fuel line is wrapped three times around the exhaust (but that is not a concern here)
Each tank has its own valve, 2 of the tanks are for veggie and the third is for diesel. Because of my long runs I fill a veggie tank when necessary and allow it to heat up for a day using ambient genshed temps until it is needed. My fuel line drop is around 4 feet or so.
I have never had a problem with this system, even when using the bigger 28hp vertical twin you can see in the pics. I would suspect a couple of things - you have a small hole in a fuel line allowing air to get in or your cylinders are not balanced. Let me know if you think either may be a problem and I'll see if I can walk you through it.
a suggestion if i might, check out a hydaulic fitting shop
i have found low pressure check valves there, that is if you have
one locally.
failing that, making one is not difficult, a ball out of a ball brg is easy
to use as the sealing element, the body can be made up of brass fittings
such as a couple of nipples and a a coupling
file one nipple nice and flat, and the other file some notches
screw the two into the coupler with the ball between
it will rest on the flat filed nipple and seat, and if it went toward the other nipple
the filed notches will keep it from seating.
if you use a spring is must be very light indeed, it doesn't take much spring tension
to effectivly shut off a gravity flow system.
another tip, before you assemble the flat filed nipple, place the ball over it and tap it
with a small hammer, this will form a very good seat in a brass nipple.
bob g
Hi Jens
I felt compelled to mention make sure your system can deal with the backpressure that check valves
often create. Also I have used in automation projects that were sensitive to backpressure actuated
ball valves. They are available with Pneumatic, Spring, AC and DC electric actuators as well as
manual overide options. Large ones are quite expensive!
Rob
Hello Jens,
Have you ever checked out http://www.mcmaster.com
They have pretty much everything.
Henry
Jens, just a thought, (and it may well be a brain phart) have you looked at a check valve from a car's vacuum system? They are small,
free if you have a donor car around, and simple. I just don't know what the veggie would do to it. They have to be gasoline-proof to be used on a car. I don't know what size you need, but larger ones are found in the power brake booster line, most of the time complete with clamps. This idea is worth what you paid for it I guess!
Ron
Jens,
I think the one on my Toyota truck is metal, but it's clamped in a rubber line. I will look later if you are interested and try to post a pic.
And I do have a spare on a "donor" vehicle.
Ron.
The toyota 1 ton I have IS plastic, but I would have bet a dollar to a donut that the junk
81 4x4 down behind the barn was metal, I went to look but guess what, it's gone. Sorry about that I can't remember squat anymore.
Anyway I should have made it a little more clear, I was thinking about the check valve on the brake booster, not the PVC valve.
Ron
jens
Could you find and install a gauge after the booster pump so you could see if the pump is working?
Just a tee in the line and a foot or two of clear fuel line full of air and plugged at the top and held vertical would form a cheap low pressure gauge of sorts. The more the fuel compresses the air that is trapped the higher the pressure. After it helps find the problem you could remove it, less parts to break.
Are you real sure that the fuel filter isn't plugged up from the veg oil? Weren't you using a real fine filter?
Good luck. Back to soybean harvest tomorrow may finish, then on to corn.
Billswan
Pulse type pumps are unecessary trouble even the good Weber website advised against these and I believe this also. Use rotary type pump ideally mechanically driven by lister's if you can machine a mount onto somehow.
PS: reason I was saying this was I am using the fuel regulator downstream of fuel pump. Pump is mounted on the engine block and is driven by cam. Pump is pulsing too much and not making regulator working right. Eventually, I'd have to get around to install rotary electric pump in my Caravan.
Cheers, Wizard
Quote from: Jens on October 10, 2009, 09:57:12 PM
As an example, just now I went to start the engine. I started the fuel pump, confirmed that it was vibrating and doing something, looked at the fuel pressure and I get regular (low) pressure based on fluid head. I jiggle the pump all over the place and gradually I get a bit more pressure here and there until it catches and I have good pressure. Now, with the engine running at full load, I still have good positive pressure.
It does rather sound like you have a duff pump there. Could it be when it's rattling & vibrating that it's actually not doing much in the way of pumping? I've had that happen to petrol fuel pumps before now, when the shaft got out of balance due to worn bearings, it sounded like it was working its tits off, but no actual fuel was being delivered...
Quote
In any case, it is too flaky for prime time operation. Ideally I would like to find a low pressure pump that is spec'd to run veg oil. So far I have not found such a beast.
See if you can find a peristaltic pump of a suitable size for your requirements. IMHO, this would be your best pump option.
Quote
One thought I have had but have not tried ... a lot of systems circulate fuel continuously for some reason. I don't know the thoughts behind such a system but it might get more flow through the pump and prevent stalling. I would take fuel out of the tank, go through the filter and then circulate back into the tank. A T after the filter would give the engine fuel with very little pressure and with no chance of negative pressure which causes all the issues.
Anybody know why fuel would be circulated continuously like that ? Less load on the pump ? Anything else ?
There's a couple of reasons:
1) By continuously circulating the fuel, you can specify a high-pressure pump to guarantee working pressure no matter how high the load (fuel usage). Fuel that was pumped but not used, of course, returns to the tank
2) In modern common rail diesels, the injectors always have HP fuel available to them; they can then be triggered electronically, allowing for better efficiency & power depending on engine RPMs, compared to the fixed-timing of a purely mechanical system.
For your system, you could use a continuous fuel pump - e.g. a peristaltic pump, to cope with the veg oil - followed by a Y split. One arm of the Y goes back to the fuel tank via a pressure regulator. The other arm goes to the engine, as per your current setup. The pressure regulator will ensure the pressure is relatively constant in the entire fuel system below the pump. Ideally, you'd want a variable regulator so you can configure it to the pressure that works best with your system. I have no idea if such things are available; but I guess it wouldn't be that difficult to make one if required (maybe out of an old bathroom tap).
Jens;
I have found that the pony pump I (used to) use for transferring cleaned veggie to my Biodiesel reactor quickly lost its "oomph". A quick check of it shows that the impeller (plastic) has been severely damaged by either the veggie or what is in it. It still made all the appropriate noises, just didn't deliver - sorta like a politician.....
jens
I know biodiesel is hard on some types of fuel lines veg oil may be too?
The pump may be bad because of the veg oil like adev and john f addvise.
Check your lines and your pump.
Billswan
I've been using a Walbro diaphragm pump in my mercedes and my 6.5 Chevy Suburban for 2 years with no issues. They provide 5-12 PSI (depending on model). Noisy clacking things, but they have served me well. I don't know how the seals would deal with bio, but 100% SVO hasn't slowed them down.
bschwarts
What walbro pump is it?
Rob
It is an FRB5.
I didn't purchase from this company, but here are the specs.
http://www.fuel-pumps.net/frb51.html
-Brett
Thanks
Quotehow do peristaltic pumps stand up to continuous usage - does the tubing not need regular replacement on these ? I like the idea !
I don't know, is the honest answer. The only one I've actually seen in use is used to bleed brake lines. Whilst googling (because I couldn't remember the name "peristaltic", I came across a few references to them being rated for continuous duty, and the line lasting for "millions" of cycles...
One thing that did occur to me; they may be self-regulating as regards downstream pressure - because there'd be some leak-back past the moving "thing" in the pump; so maybe you'd be able to avoid a return pipe & regulator; however, the only low-cost examples of peristaltic pumps that I can find really do provide miniscule amounts of liquid (4.2ml/minute was what one of them quoted).
Edit: Thinking about it, they use peristaltic pumps for heart bypass and dialysis machines; I'm sure it must be possible to get both the pumps, and replacable piping for those, relatively cheaply; is there such a thing as hospital surplus?
jens
That is one big ass pump, 8 to 11 PSI and 45 gph my gosh isn't there a smaller pump out there somewhere?
It says industrial but don't you think that is a little bit to big for your oid? Divide the GPH output by 10 and that would be to much!
If all your fuel line is in good shape inside (no collapsing liner) and you are sure it is the pump you now are using why not take it apart to see what makes it tick. It might be fixable.
Billswan
Quote from: Jens on October 13, 2009, 10:03:27 AM
Now that is weird, I only saw your reply by accident. I normally just click on 'read new posts since last visit' (or whatever) and your post never came up.
Jens
Jens
Have noticed some glitches in the software like you note above, thought it was just me or my computer.
Have also noted others making mention of other problems. Wounder what is up?
Still think you should give the pump you have, a look see, maybe it can be modified to pump the veg oil perhaps a heaver spring or a internal relief or possibly a new oring of some other type of rubber and it may fix the problem. Aren't you the least bit curious why it doesn't keep pumping and jams up?
Billswan
Jens,
I would like to respectfully challenge your diagnosis.
180 Deg. F veggie oil is very similar in viscosity to dino-diesel.
The theory of the plunger grabbing or sticking due to viscosity would only be valid if you think the temperature of the oil is cooling before it reaches the pump. If that is the case, perhaps some additional heating is in order (heat wires around the pump ??).
If you can tolerate the exhaust odor, run some dino for a while and see if the problem pops up.
Just a thought...
Veggie
Jens, I think you will be really pleased with the performance of the pump. They tolerate a lot of extremes. My single tank Mercedes pump works in the winter pushing COLD (30 degree F) veg from the tank, and the pump on the suburban sees oil after it's been heated to around 160. As you are just trying to get fuel to the injection pump with no real need for pressure, the Walbro will click away happily for years.
If it isn't too inconvenient, run it as a pressure pump. These are always recommended to be run as close to the tank as possible. They push MUCH better than they suck.
Why is it easier to pull a rope than to push a rope?
Is it easier to blow water through a hose, or to suck it?
I guess with the racor, if you use suction, it is impossible to pressurize it beyond atmospheric, and to much pressure could cause a leak (around seals, not necessarily external). With the pump, only atmosphere will fill its small cavity for pushing, and at the end of a long run of fuel line, not much (particularly oil) flows quickly enough to fill that spot. As you don't need any real pressure (unlike a vehicle engine), I don't think placement will really matter. We also aren't talking about a 10 foot run like under my suburban.
Most electric pump manufacturers will void the warranty if the inlet is not filtered.
Ron