Forum › Forums › Tractor Troubleshooting › Jinma 284 fuel Injection problem
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June 5, 2014 at 12:06 am #37020
What is your low idle speed? Should be around 650 r/m.
Are you getting black exhaust smoke at anytime?
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June 5, 2014 at 9:43 am #37022
The idle speed is not too low. It idles well and picks up RPM fine before it has run long enough to starve. There is no heavy blue or black smoke, even when it is starving. I would like to figure out a way to determine if the cylinders are flooded with fuel, but it is not smoking. My test is to run it up the driveway a bit, which is uphill. When I stop and throttle down it immediately starts starving, so I put the tractor in reverse and back down the hill. With the help of gravity it is easy to get it revving again and it responds to the throttle, but back at the bottom it will not even get close to idle in neutral without struggling to run at all (but if I keep the RPM up it is o.k.). Once I let it idle down it starves and opening the throttle makes little difference, pumping the manual lift pump makes no difference. Sometimes I can hold the throttle open and it will very gradually pick up a little speed, but not much.
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June 5, 2014 at 11:03 am #37024
Still sounds like its starving for fuel, Did you take the sediment bowl completely off ? There is a screen on top of it inside the fuel tank ?, Also the bolt that holds the rubber fuel line to the bottom of the primer pump has a screen inside of bolt ? did you check it ?
Tommy
Affordable Tractor Sales
“Your Jinma Parts Superstore”
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June 5, 2014 at 12:41 pm #37027
If it isn't smoking and there are no perceivable loud knocks there is no over fueling (there is no flooding in a diesel engine – no carburetor
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There is no direct mechanical connection between the hand throttle controls and the fuel rack. The fuel rack is operated through the governor flyweights. All the hand throttle does is control the flyweights via the speeder spring. You may have a sticking rack, which is not uncommon, or you may have a weak speeder spring, very uncommon. Since it is a brand new unit, I suspect a sticking rack. What oil are you using in the injection pump?
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June 5, 2014 at 12:45 pm #37028
Tommy,
I just re checked the screen on the intake to the primer pump and it is perfectly clean and diesel pours out the hose when I turn on the valve at the sediment bowl. The screen in the sediment bowl was just changed when I replaced the sediment bowl.
It will keep pulling as long as you want without starving, but will immediately starve when you stop pulling.
/Jon
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June 5, 2014 at 2:05 pm #37029
Try, turning the valve on the sediment bowl only half open see if the reduced amount of fuel flow helps ???.
Tommy
Affordable Tractor Sales
“Your Jinma Parts Superstore”
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June 5, 2014 at 6:17 pm #37031
Tommy,
I took off the hose and noticed where I can position the valve to get just a trickle of fuel. Ran the test and it still starves. It might be my imagination, but it seemed like it was slightly better. I held the throttle open and after awhile it gradually started to pick up RPM. Once it was revving it was responsive, then I let it idle back down and it was starving badly again.
I am wondering if this could be a timing problem how can I be sure where the correct timing is. My timing gear with centrifugal advance was, I'm guessing, an off the cuff design change that might not have been documented or adjusted for with different timing marks on the front pulley. I have a TDC mark preceeded by two marks closer together. It would not surprise me if these marks were for the engine before the centrifugal advance was used and I'm wondering if they are still in the right place. Does anyone know if the timing is set the same with or without the centrifugal advance? I currently have the spill stop spilling just as it gets to the first before TDC mark, but I have also had it start to spill there, as well as a hundred other places. Any ideas on how to eliminate or confirm if it is a timing related problem? I checked with an injector shop and they told me they almost certainly would not be able to test this injector pump.
/Jon
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June 6, 2014 at 8:13 am #37033
Sounds like it may be the timing then, I have not set the timing on one with the advancer on it, not sure how to do it.? Hopefully someone on here has and can help
I'm surprised that the fuel injection shop you went to could not help, these pumps are Bosch design, and we have had several people take them to injection shops, only to find they could buy a new pump for less than the cost to rebuild and re-calibrate the old pump would be.
In your case it seems like the pump is working, did you replace it ? how did the timing get off ?
Tommy
Affordable Tractor Sales
“Your Jinma Parts Superstore”
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June 6, 2014 at 10:00 am #37034
Tommy,
Yes, the pump was replaced. The old one sheared the key. Is there any way the pump could work normally, then starve? Is there any governor mechanism that could be malfunctioning?/Jon
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June 6, 2014 at 11:54 am #37035
Yes they all have a governor that could malfunction but you should see if you can find a tractor repair shop to take a look at it.It could be something minor, send me a pic of your pump ,to see it I can see anything from looking at it
tommy@affordabletractorsalesco.com
Tommy
Affordable Tractor Sales
“Your Jinma Parts Superstore”
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