YM1700 injector timing question

[careyo63]

Looks like when I first cold start the YM2000 after It's been sitting a week or so. After I let the Decompression go and it hits the first couple of times. You can see the moisture Grey/White smoke come out the exhaust the first few hits and then Bang! it comes to life. Always done it and it clears right up with minimal smoke. I set the Throttle for no higher than 2000 Eng. Rpms. and then slowly lower it to 1200 for a min..
That amount of Grey/white looks to be a compression problem Head gasket etc.. Clean the fuel tank out and new Fuel/FuelFilter and see it it helps! Cheap and easy to check first. NAPA. #3262 filter

 

[goose117]

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Peter - I agree the smoke isn't really that black after looking at it again. I did check for bubbles and oil in the radiator and I don't think I'm getting either.

Careyo63 I did empty the tank and put a new filter in. Didn't seem to change the behavior.

One thing I noticed with a clear tube between the fuel bowl and the injector pump is that after bleeding at the fuel bowl, pump, and injectors I could see there were no bubbles in the clear line. When I started up I saw a lot of bubbles filling that clear tube. I even saw a few small bubbles generated just while turning over to start. I hadn't put much fuel in the tank in case I needed to empty again for some reason. I looked in the fuel tank while the tractor was running and could see the fuel "fountaining' up from the tank drain. See around 10 s into this video. It seems like one way to avoid this would be to just have more fuel in the tank (which I'll try) but should this be happening?

Fuel fountain in fuel tank

Bubbles in tank and fuel line tank half full

 

[bmaverick]

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Peter - I agree the smoke isn't really that black after looking at it again. I did check for bubbles and oil in the radiator and I don't think I'm getting either.

Careyo63 I did empty the tank and put a new filter in. Didn't seem to change the behavior.

One thing I noticed with a clear tube between the fuel bowl and the injector pump is that after bleeding at the fuel bowl, pump, and injectors I could see there were no bubbles in the clear line. When I started up I saw a lot of bubbles filling that clear tube. I even saw a few small bubbles generated just while turning over to start. I hadn't put much fuel in the tank in case I needed to empty again for some reason. I looked in the fuel tank while the tractor was running and could see the fuel "fountaining' up from the tank drain. See around 10 s into this video. It seems like one way to avoid this would be to just have more fuel in the tank (which I'll try) but should this be happening?

Fuel fountain in fuel tank

Bubbles in tank and fuel line tank half full

WOW

So, the fuel bowl and o-ring are new? This condition has been seen before when a hair-line crack in the fuel bowl or the o-ring doesn't seat well. The fuel pump is pulling fuel and the suction is so much, air from the outside comes in thru the cracks, thus the bubbles.

Additionally, Does this machine have a thermo-start? The device at times is feed from the fuel tank and not a small reservoir. If there are leaks or bad lines there, then air is getting in.

 

[thepumpguysc]

Good video of the “problem”..
That is indeed odd..
Is there any way to reroute the return.??
Is that the fuel outlet, to the filter, directly under the return bubbles.??
Just as a test, grab a spatula, preferably off the grill, and see if u can block off the bubbles from the outlet..

 

[thepumpguysc]

That test will tell u if the bubbles are coming from the return fuel or a hairline crack like bmav. suggested..

 

[goose117]

The fuel bowl assembly is new. The tractor doesn't have a thermo-start.

The fuel jumping up in the tank in the video is directly over the outlet that runs to the fuel bowl. It almost seems like there is some back pressure into the tank at the outlet being viewed in the video but there is a net flow of fuel to the injector pump.

I may try an auxiliary tank directly to the injector pump to see if that bypasses the bubbles.

I like the idea of some sort of deflector above the gas tank fuel outlet too to see if that reduces the turbulence and bubbles.

 

[ponytug]

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Peter - I agree the smoke isn't really that black after looking at it again. I did check for bubbles and oil in the radiator and I don't think I'm getting either.

Careyo63 I did empty the tank and put a new filter in. Didn't seem to change the behavior.

One thing I noticed with a clear tube between the fuel bowl and the injector pump is that after bleeding at the fuel bowl, pump, and injectors I could see there were no bubbles in the clear line. When I started up I saw a lot of bubbles filling that clear tube. I even saw a few small bubbles generated just while turning over to start. I hadn't put much fuel in the tank in case I needed to empty again for some reason. I looked in the fuel tank while the tractor was running and could see the fuel "fountaining' up from the tank drain. See around 10 s into this video. It seems like one way to avoid this would be to just have more fuel in the tank (which I'll try) but should this be happening?

Fuel fountain in fuel tank

Bubbles in tank and fuel line tank half full

Nice videos, but I suspect that this is a side issue, related to basically no fuel in the tank.

While it is possible that there is a leak in your bowl/fuel line that is letting some air in, I would retry this with a tank that is at least 1/4 full. You can get a lack of proper fuel flow if the fuel system has air in it, either issues in the injection pump, or fuel lines to/from it, or in the lines to the injectors, or the injectors themselves. Does the fuel tank weep fuel at all, possibly from the tubing adapter at the base? Once you have the whole fuel system primed, and free of air, I would see if the engine runs any better. If it doesn't, I would pull each injector one at a time and check for a reasonable spray pattern out of the engine.

Since this problem happened to your engine suddenly, I would be looking for a part that failed mechanically; cracked fitting, cracked tubing, broken injector, or an injector pump that had the linkage give out.

I had a problem on an overfueling Yanmar clone engine that turned out to be a minuscule crack fracture at the base of the inlet to the injection pump, making external bubbles of about a 1/16th-1/32nd of an inch in size. The tiny amount of air getting in was enough not to have the injection pump get up to enough pressure that the injector just dribbled fuel into the cylinder.

Good luck, and good hunting!

All the best,

Peter

 

[goose117]

I tried an auxiliary tank sitting on the air cleaner bypassing the fuel bowl and filter. There were no bubbles and the tractor didn't stop on its own. It still is a bit difficult to start and is still smoky but progress. So I think I need to work on the fuel bowl and tank plumbing for the bubble issue.

In one of the earlier posts I mentioned that the tractor had run reasonably well for 20 years and then I couldn't start it. With only occasional windows of time to work on it over the last few years I replaced many parts so it really hasn't run normally since then. I'm optimistic it's getting close though. Thanks all for the feedback and suggestions.

Some posts back are some videos of the injectors firing but not sure that the atomization is what it should be or how much that would effect the current issues.

 

[careyo63]

The low fuel and air bubbles needs to be taken care of. It's gravity fuel fed to the Inj. Pump. If or when the smallest amount of air hits the Inj. pump it looses prime. The bubbles in the tank are normal. Mines shows up with a low fuel level, But no air in the line that I could see. looking hard Esp. before the Inj. pump.
What problem I did have was my Fuel Tank would get Pressured up and I could actually see the air bubbles leaking at the Inj. return line. Were it inserts back into the tank. I would end up with Small Puddles of fuel on top of the tank. A small piece of rubber vacume line and ran the Hard plastic return fuel line through it to and seal up that one. I also vented it with a Filter through the cap. Just a 2 cycle fuel filter from inside the tank. Weedeater I believe.
It's been many Yrs. So things are hard to remember but I keep thinking that There was a problem I noticed going through and cleaning repairing everything of the Fuel tank itself at the fuel line connection was pretty much clogged up. The cut off is on the Fuel Filter Assm. so I knew that wasn't good. Something tells me the oil ring around the fuel bowl basically disintegrated also and had to actually make one fit.
One reason I bought it was Org. and looked as if it just rolled of a boat from Japan! From a local Fredricks supplied dealer. Knowing I could get parts etc. from Fredricks now I'm still all org. with only basic repairs needed to make and keep it that way. Coming up on 1000 Tach Hrs. Mid 900's it's my lawn mower LOL... What I actually bought mainly to use it for.

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[ponytug]

I tried an auxiliary tank sitting on the air cleaner bypassing the fuel bowl and filter. There were no bubbles and the tractor didn't stop on its own. It still is a bit difficult to start and is still smoky but progress. So I think I need to work on the fuel bowl and tank plumbing for the bubble issue.

In one of the earlier posts I mentioned that the tractor had run reasonably well for 20 years and then I couldn't start it. With only occasional windows of time to work on it over the last few years I replaced many parts so it really hasn't run normally since then. I'm optimistic it's getting close though. Thanks all for the feedback and suggestions.

Some posts back are some videos of the injectors firing but not sure that the atomization is what it should be or how much that would effect the current issues.

My apologies. I had forgotten the nice injector spray video that you posted. That one looked great.

Try the bleeding procedure that @bmaverick posted, and see how it goes. If you still have issues, I would be looking at the injector pump. @thepumpguysc any thoughts?

All the best,

Peter