Go BottomCrank but no start
 | Piper2023
Join Date: Jul 2025 Posts: 2 Texas 
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2025-07-20 201899
2008 3cyl diesel cub cadet utility tractor will start then immediately die when let go of key. Good fuel was running fine. Researched here and replaced fuel selinoid on pump. It will run with selinoid removed. Can’t find a wiring diagram for that tractor. Only has 65 hrs. Any help???
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Add PhotoCrank but no start
| Tractorpoint
Join Date: Oct 2006 Posts: 20 NJ
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2025-08-01 201902
It absolutely sounds like the hold circuit (run-position coil) on your fuel shut‑off solenoid isn’t being energized, even though the pull‑in circuit (start coil) works fine — hence it runs while you're holding the key in “Start” but dies the moment you release it
🔌 What’s going on internally:
Most diesel fuel shut‑off solenoids have two internal coils:
Pull (Start) coil – energized only while cranking to open the valve.
Hold (Run) coil – keeps the valve open during normal engine run after releasing the key.
The hold coil draws less current and is powered only in the Run key position
From your description: removing the solenoid completely allows the engine to run — indicating that the pull-in coil works when cranking, but no power is being sent to the hold coil in the Run position.
✅ Steps to troubleshoot:
1. Test for voltage at the solenoid when key is in RUN
Unplug the solenoid and use a multimeter or test light.
Crank the engine (key at Start). You should see ~12V on the "start" coil feed.
With the engine running and key in Run (not Start), check the hold coil terminal — it should have ~12V. If it doesn’t → wiring or ignition switch issue.
2. Inspect the ignition switch and connections
Corrosion, wear, or a failed ignition switch can cause no power in Run position.
Many tractor models (e.g., earlier Cub‑Cadets) combine the switch and small circuit board → a failure there is common
3. Follow wiring from solenoid to switch
Trace the hold circuit wire back from the solenoid to the ignition switch connector.
Inspect connectors, relays, and any interlocks (seat switch, PTO safety) in series—which may interrupt hold-power when in Run.
4. Check for blown fuse, relay, or safety interlock behavior
Some machines route the solenoid hold circuit through safety switches (seat, PTO, transmission neutral). If not engaged, no hold power.
Also supply fuse or relay may feed this, check for blown fuse or bad relay
🧰 Summary of focus areas
Component What to check
Hold coil terminal (solenoid plug) With key in Run: should show 12 V
Ignition key switch Does it supply +12 V to hold circuit in “Run”?
Wiring harness Broken connection, corrosion, loose connector
Safety interlocks Seat switch, belt, PTO – must be engaged to complete circuit
Fuse / relay Blown fuse or bad relay on the hold circuit line
What to do next
Confirm the hold-coil isn’t receiving voltage in Run.
If no voltage, check ignition switch and wiring.
Clean and re-seat connectors, apply dielectric grease.
If the ignition switch is old or exposed, consider replacement—even if hours are low.
Test all safety interlocks and replace fuse/relay if found faulty.
This isn’t a carb or injection problem since it runs fine without the solenoid. Instead, the symptom perfectly matches a missing 12 V hold signal for the solenoid. Passing current through that hold circuit keeps fuel flowing.
If you can access a multimeter, these voltage checks are your best diagnostic route. ....
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