Problems with one cylinder on a 20/2

[Jens]

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

[mobile_bob]

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

[Henry W]

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

[T19]

Talk to JohnF, he has lots of experience with twins.  Sounds like your getting an air leak somewheres

[admin]

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

[JohnF]

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.

[mobile_bob]

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

[rl71459]

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

[Henry W]

Hello Jens,

Have you ever checked out http://www.mcmaster.com

They have pretty much everything.

Henry

[vdubnut62]

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

[vdubnut62]

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.

[vdubnut62]

 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

[billswan]

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

[Wizard]

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

[AdeV]

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...

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.

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).