Oil & Fuel New to me YM2500

[ponytug]

Speaking from experience, a pin hole air leak can cause very weird behavior in a diesel; stumbles at lower speed, stumbles under load, excessive fuel usage, and overheating exhaust. All caused by poor injection behavior of the fuel being too compressible with the trace of air in it.

Good luck!

All the best,

Peter

 

[bmaverick]

When the engine is running, I keep hearing that 'tinned' sound. Our machines have the same engine and at the very low idle it sounds like my engine, but increasing the RPMs it sounds so strange.

There is a governor rod inside the engine at the very bottom and to the governor at the back of the engine. Pulling off the bottom oil pan you can examine this. The trouble is, you will then need a replacement gasket for that pan cover.

If that rod is bent or not correct, it would explain why the engine drops to idle.

With the throttle linkages, are there and weak springs?

Check out the attachments.

The YM2500 came in 3 variations. YM2500, YM2500L and YM2500R.

And take a look at item-13 on pg-11.

 

[Brokeodie]

Thank you both.. i am going to make sure there is no air in fuel problems. I have a fuel pump I'm thinking of throwing in to see if that corrects the issue. I'm also wondering if the pinging sound could be an injection pump timing issue so even though it's not smoking i should check that. Trying to rule out the external stuff before I start tearing into it or paying to have someone tear into it.

 

[ponytug]

I don't hear the "tinny" sounds, but I do see/hear the collapse as the throttle drifts down.

Continuing @bmaverick's thoughts on sticky governors, I wondered if there might be gunk elsewhere. These machines were design for high lubricity (aka high sulfur) diesel. As the tractor is new to you, have you run a double dose of injector clear through the system yet, and are you adding something to boost the lubricity of the fuel? (E.g. 2% Biodiesel, opti-lube, Standyne, Powerkleen)

After it making a big difference to an old engine, I am a fan of Tuffoil for when things are sticky and just "ADR" ("ain't doin' right"). I'm not generally a fan of additives, but that one is always in my personal toolbox for getting things to run more smoothly. A little goes a long way.

All the best,

Peter

 

[CoyPatton]

I agree about additives, typically I am not a fan. That said there are times they area must! Some that come to mind with fuel are 1) older diesels that were designed around high sulfur fuel and today’s ultra low sulfur fuels—sulfur was a great lubricate in fuel, terrible for the air as an exhaust. Use an additive for extra lube 2) anti-gelling—summer fuel will have very little if any, it is a pain to need your tractor in a winter day and fuel gelled in the lines. 3) I have rebuilt a few older engines designed around high lead content in fuels of the day. The non lead fuels of today are hard on these old engines. If you have one, get the additive!
I running a lube additive in my early 80’s model diesel tractor with every tank full. Plenty of brands out there for you to pick from.

 

[Brokeodie]

Hi Peter,

I am already using 20% biodiesel and will put in some Opti-Lube. The fuel pump is a fresh rebuild and the injectors are new. Because it runs fine at high rpms I don't think its a fuel starvations issue. So I am left with, governor, throttle linkage, or lines causing minute air bubbles. When I took the inspection plate off and fuel pump to send it off I was surprised how clean the interior was. There is some slop on the linkage going into the motor and even that could be the cause but am trying to rule out all of the outside things before I go inside.

But as always appreciate the comments as they always help keep me going.

 

[ponytug]

Having the inspection area and fuel pump look clean is certainly a good sign, whatever the issue is.

I am assuming that you don't have any existing fuel wet spots.

When you go over the fuel system looking for leaks, I would suggest loosening and then tightening each fitting sequentially from the fuel tank onward and listen if the engine has a problem. I would also disassemble and double check the fuel filter gasket and gasket surfaces for any crease, scratch, grit, or hair. It is a common place to get an air leak because of the vacuum. The same on the pressure side, loosen each nut, let diesel weep out and tighten it. Sometimes, it is a little grit on the fitting surface and cracking the fitting open flushes diesel out under high pressure and dislodges the offender. At the same time, if you loosen a fitting and it doesn't get worse, but the corresponding ones do, that suggests that that particular fuel line/fitting is your problem child.

Wear gloves when working on the high pressure side for protection against any high pressure streams of fuel.

All the best,

Peter

 

[Pearlsnaps]

Mine was air in the fuel. After replacing all of the lines, emptying the tank to clean it, and starting over with new diesel and new lines.... I also made this contraption based on some other threads i read with "ghost" air in the lines. Basically, I couldn't locate where the air was coming from prior to the injector pump. New fuel filter after this photo as well.
Just ran for over an hour for the 1st time in 9 months... The top line is Teed into the fuel return line going back to the tank. Hope this helps ya.

 

[Brokeodie]

So quick update:
I may have figured out the problem. The fuel filter assembly was missing o-rings on the bleeder screws and the fuel shut off lever's o-ring had some flat spots. Going to harbor freight to pick up an o-ring kit and hope there are some that will fit as i can't seem to find the proper size in the parts catalog.

 

[bmaverick]

So quick update:
I may have figured out the problem. The fuel filter assembly was missing o-rings on the bleeder screws and the fuel shut off lever's o-ring had some flat spots. Going to harbor freight to pick up an o-ring kit and hope there are some that will fit as i can't seem to find the proper size in the parts catalog.

Whoa, make sure you buy o-rings that are rated for diesel fuel. You don't want them to turn mushy and chemically melt away in the fuel. You'll have a gummy up mess.

You must understand o-ring compatibility before just running down to H-F.

Buna-N or Nitrile is highly resistant to hydrocarbons. The greater the nitrile content in the material, the greater the resistance to decay in a hydrocarbon environment. It's one of the most highly used seal materials in the oil and gas industry. Long as your o-ring is the correct size, buna-n should hold up just fine to diesel fuel.