Hi I’m a new member here. I recently brought home a JD650 and have what I believe to be a fuel injection pump issue. I now need to find someone that rebuilds and calibrates these little pumps or has them available to swap out with my core.
And I look forward to bringing my little tractors future problems here!
If your JD650 engine runs poorly or not at all and you suspect the
fuel injection pump, here are the most likely issues:
Possible Problems:
- Stuck or gummed-up internal parts – after sitting for a long time, diesel residue (varnish) can cause the internal plungers and governor to seize or move sluggishly.
- Worn delivery valves or plungers – this leads to low injection pressure and uneven fuel delivery.
- Failed pump seals or return check valve – can cause fuel leakage back to the tank, making starting difficult.
- Timing or calibration off – if the pump was previously removed or adjusted, even a small misalignment can affect power and smoke
Fastest and Most Efficient Solution:
1.
Do a quick fuel system check:
- Confirm that the fuel is clean and the filters aren’t clogged.
- Bleed all air from the system up to the injector lines.
2.
Tap test (for mechanical inline or rotary pumps):
Sometimes a light tap on the pump body while cranking helps free a sticky governor — if that temporarily improves response, internal cleaning is needed.
3.
Remove and send the pump to a diesel injection specialist:
It needs to be
bench-tested and recalibrated on a test stand.
A professional rebuild includes cleaning, new seals, setting plunger delivery, and calibration to OEM specs.
If you can’t find a local shop, many aftermarket service centers accept
core exchanges (you send yours, they send a rebuilt one).
For compact equipment users, we’ve had good results using
Fairy Deer’s precision-calibrated gear-type transfer pumps — they’re designed to match small diesel injection systems and can often restore stable fuel delivery without the need for a full pump replacement if the issue is just low supply pressure.
