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I have a 2005 Jinma 284 with the “EPA” Laidong engine. The injector pump seized and the timing gear sheared the key and turned on the shaft. I have found the correct position for the timing gear on the new injector pump and have carefully spill tested to find what I believe to be the correct timing, but have a problem that I have not been able to resolve. The engine sounds like it is running well and seems to pull o.k., but when allowed to idle down after running for several minutes it acts like it is starved for fuel. Pumping the manual lift pump has no effect, and I can hear the fuel being pumped into the tank. The amount of diesel that squirts out of a loosened injector line appears the same when the engine is “starving” as when the engine is running normally (not in the starving situation). Once in this situation the engine has to sit for a while before it is ready to run again, otherwise there is practically no response to the throttle and the engine can barely keep itself running with no load. I have checked that the pressure building valve on the bypass exit from the injector is working properly and is in the right place and have swapped it with the old one, but this makes no difference. I have changed the filters, fuel lines and sediment bowl. I have changed the timing a little at a time through its entire range, even tried a tooth over on the timing gear. This timing gear has a centrifugal advance with weights that change the timing as they spin faster. I have changed the starting position of these weights many times and verified that they do change the timing when the motor is spinning. Nothing I do seems to affect the problem. I have come to the conclusion that the engine might not actually be starving for fuel, but flooding. Maybe the fuel is being injected at the wrong time and builds up in the cylinders to the point where it no longer ignites and burns properly. Does anyone know what might be causing this, or what troubleshooting techniques I can use to narrow down the cause of the problem?
/Jon
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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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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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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
).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?
Account deleted.
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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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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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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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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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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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