feat: Add CrankNoStart issue for ATV no-start problem
- Document crank no-start condition with suspected carburetor issue - Include battery drain issue as related problem - Create diagnostic procedure: verify spark and fuel before assuming carb problem - Add parts list and repair procedure for systematic troubleshooting - Prevents jumping to carburetor rebuild without confirming root cause
This commit is contained in:
John Loper II
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# Issue: Crank No-Start Condition
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> **See main overview:** [README.md](../README.md)
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---
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## 📋 Quick Summary
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**Issue:** ATV cranks but will not start
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**Date Reported:** 2026-03-22
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**Mileage/Hours:** TBD
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**Severity:** Medium - ATV unusable for work/recreation
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**Status:** 🔍 INVESTIGATION - Need to confirm spark and fuel
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---
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## 🚜 Vehicle Details
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- **Year/Make/Model:** 2001 Polaris Sportsman 500HO
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- **Engine:** 497cc V-Twin 4-stroke
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- **Serial Number:** TBD
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- **Current Mileage/Hours:** TBD
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---
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## 🔍 Problem Description
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**Symptoms:**
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- ✅ Engine cranks normally
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- ❌ Engine will not start
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- **Fuel delivery:** Unknown - needs confirmation
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- **Spark:** Unknown - needs confirmation
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**Related Issue:**
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- Battery consistently dies on this ATV
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- May indicate charging system issue or battery problem
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**When it Occurs:**
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- [TBD - When did this start?]
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- [TBD - Does it happen every time or intermittently?]
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- [TBD - Any conditions that affect it?]
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---
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## 🎯 Initial Assessment
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### Suspected Cause
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- **Carburetor issue** - John suspects carb problem but has no confirmation
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- **Battery/charging issue** - Battery consistently dies
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- **Could be multiple issues** - No spark AND no fuel possible
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### Diagnostic Priority
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1. **Verify spark** - Confirm ignition system is working
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2. **Verify fuel delivery** - Confirm fuel is reaching cylinders
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3. **Check battery/charging** - Address battery drain issue
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4. **Carburetor inspection** - Only after confirming spark and fuel
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---
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## 📊 Diagnostic Findings
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### Current Status
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**NOT YET TESTED** - Need to perform diagnostics
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### Test Results
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| Test | Expected | Actual | Status | Tested At (YYYY-MM-DD HH:MM) |
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|------|----------|--------|--------|------------------------------|
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| Check for spark | Spark present | TBD | ⏳ Pending | TBD |
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| Fuel delivery | Fuel reaching cylinders | TBD | ⏳ Pending | TBD |
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| Battery voltage | 12.6V+ (fully charged) | TBD | ⏳ Pending | TBD |
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| Charging system | 13.5-14.5V while running | TBD | ⏳ Pending | TBD |
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| Carburetor sync | Synchronized | TBD | ⏳ Pending | TBD |
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| Air filter condition | Clean | TBD | ⏳ Pending | TBD |
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| Spark plug condition | Good | TBD | ⏳ Pending | TBD |
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### Diagnostic Data Collected
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- [ ] Spark plug removed and inspected
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- [ ] Spark tester connected to plug
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- [ ] Fuel flow verified
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- [ ] Battery voltage measured
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- [ ] Charging system tested
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---
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## 🎯 Theories & Root Cause Analysis
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### Most Likely Causes (ranked by probability)
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1. **Carburetor Issues**
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- **Why:** Most common cause of no-start on carbureted ATVs
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- **Evidence:** John suspected this, but needs confirmation
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- **How to confirm:** Remove carb, inspect jets, check float level, clean thoroughly
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- **Common problems:** Stuck float, clogged jets, old fuel, water contamination
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2. **No Spark**
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- **Why:** Engine needs spark to ignite fuel
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- **Evidence:** Not yet confirmed
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- **How to confirm:** Remove spark plug, ground to engine, crank and check for spark
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- **Common problems:** CDI module failure, ignition coil failure, kill switch issue, spark plug fouled
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3. **Fuel Delivery Issue**
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- **Why:** No fuel = no start
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- **Evidence:** Not yet confirmed
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- **How to confirm:** Disconnect fuel line, check flow; remove carb bowl, check fuel level
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- **Common problems:** Fuel pump failure, clogged fuel filter, empty tank, old/degraded fuel
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4. **Battery/Charging Issue**
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- **Why:** Weak battery may crank but not enough for proper spark
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- **Evidence:** John reports battery consistently dies
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- **How to confirm:** Battery load test, charging system test
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- **Common problems:** Old battery, failing stator/charging coil, bad rectifier
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5. **Air Restriction**
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- **Why:** No air = no combustion
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- **Evidence:** Unlikely but possible
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- **How to confirm:** Remove air filter, try starting (temporary test)
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- **Common problems:** Clogged air filter, debris in intake
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### Common Failure Points for 2001 Polaris 500HO
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1. **Carburetors** - Dual Mikuni VM carbs need sync and cleaning
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2. **CDI module** - Can fail and kill spark
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3. **Stator/charging coil** - Charges battery and powers ignition
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4. **Rectifier/regulator** - Converts AC to DC for battery
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5. **Fuel pump** - Mechanical diaphragm pump can fail
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6. **Spark arrestor** - Can clog in exhaust
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7. **Kill switch** - Can fail and cut ignition
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### Historical Context
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- **Battery issue:** Consistently dies - indicates charging problem or weak battery
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- **No-start:** Could be related to battery (weak spark) or separate issue
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- **Age:** 2001 model - 25 years old, components may be worn
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---
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## 🔧 Tools Needed
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### Basic Tools
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- [ ] Spark plug socket (18mm or 21mm for ATV plugs)
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- [ ] Multimeter
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- [ ] Spark tester
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- [ ] Fuel line clamp
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- [ ] Catch container for fuel
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- [ ] Basic wrench/socket set
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- [ ] Carburetor sync gauge (if available)
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### Safety Equipment
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- [ ] Safety glasses
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- [ ] Gloves
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- [ ] Work stand or center stand
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---
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## 📦 Parts & Materials
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### Parts to Consider
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| Part | Part Number | Cost (OEM) | Cost (Aftermarket) | Status |
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|------|-------------|------------|-------------------|--------|
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| Spark Plug | NGK BR8ES or equivalent | $5-10 | $5-10 | 🔍 Inspect first |
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| Air Filter | Polaris aftermarket | $15-30 | $10-25 | 🔍 Inspect first |
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| Fuel Filter | Polaris | $5-10 | $3-8 | 🔍 Inspect first |
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| Carburetor Kit | Rebuild kit for Mikuni VM | $25-40 | $20-35 | 🔍 May need |
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| New Carburetors | If rebuild fails | $200-400 | $150-300 | Last resort |
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| Battery | 12V ATV battery | $80-150 | $60-120 | Likely needs |
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| Stator/Charging Coil | If charging fails | $100-200 | $80-150 | If needed |
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| Rectifier/Regulator | If charging fails | $80-150 | $60-120 | If needed |
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### Materials
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- [ ] Carburetor cleaner
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- [ ] Brake cleaner
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- [ ] Electrical contact cleaner
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- [ ] Dielectric grease
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- [ ] Fresh gasoline (no old fuel!)
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- [ ] Engine oil (if changing)
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---
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## 📚 Resources
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### Video Resources
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- 📺 [YouTube: Polaris Sportsman 500HO no start diagnosis]
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- 📺 [YouTube: Polaris 500HO carburetor cleaning]
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- 📺 [YouTube: Polaris ATV spark plug check]
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- 📺 [YouTube: Polaris ATV charging system test]
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### Written Guides
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- 📖 [Polaris Service Manual - 2001 Sportsman 500HO]
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- 📖 [Mikuni VM carburetor sync guide]
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### Parts Sourcing
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- 🔗 [Polaris parts catalog](https://www.polaris.com/parts)
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- 🔗 [RockAuto ATV parts](https://www.rockauto.com/en/catalog/polaris,2001,sportsman,500ho,1234567)
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- 🔗 [ATV parts specialists: ATVTrax, Quadboss, etc.]
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---
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## 🔧 Repair Procedure
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### Phase 1: Confirm Spark
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**Step 1: Remove spark plug**
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1. Cool engine completely
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2. Remove spark plug wire
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3. Remove spark plug with socket
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4. Inspect plug condition:
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- **Good:** Light tan/gray color
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- **Fouled:** Black carbon, wet with fuel/oil
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- **Wet:** Drenched in fuel (flooded)
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- **Dry:** No fuel (fuel delivery issue)
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**Step 2: Test for spark**
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1. Reconnect spark plug to wire
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2. Ground plug thread to engine block
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3. Have someone crank engine
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4. **Expected:** Bright blue spark
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5. **No spark:** Proceed to ignition system testing
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**If NO SPARK:**
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- Check spark plug (replace if fouled)
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- Check kill switch (ensure not engaged/broken)
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- Test ignition coil (resistance check)
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- Test CDI module
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- Check wiring for breaks/bad connections
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### Phase 2: Confirm Fuel Delivery
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**Step 1: Check fuel tank**
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1. Verify fuel is present
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2. Drain old fuel if stale (>3 months)
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3. Use fresh gasoline
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**Step 2: Check fuel flow**
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1. Disconnect fuel line at carburetor
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2. Clamp line, direct into container
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3. Turn fuel petcock ON
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4. **Expected:** Steady fuel flow
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5. **No flow:** Check fuel filter, fuel pump, petcock
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**Step 3: Check carburetor**
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1. Remove carburetor bowl
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2. **Expected:** Fuel in bowl
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3. **Empty bowl:** Fuel not reaching carb
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4. **Full bowl:** May be flooded or float stuck
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**If NO FUEL:**
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- Clean/replace fuel filter
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- Check fuel pump (diaphragm test)
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- Clean carburetor jets
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- Check petcock vacuum line
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### Phase 3: Battery & Charging System
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**Step 1: Battery test**
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1. Measure battery voltage (should be 12.6V+ fully charged)
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2. Load test battery
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3. **Weak battery:** Charge or replace
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4. **Good battery:** Check charging system
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**Step 2: Charging system test**
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1. Start engine (if possible with jump start)
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2. Measure voltage at battery while running
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3. **Expected:** 13.5-14.5V
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4. **Low voltage:** Stator/rectifier issue
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### Phase 4: Carburetor Service
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**If carburetor is the issue:**
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1. Remove carburetors
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2. Disassemble completely
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3. Clean all jets with carb cleaner
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4. Check float level and condition
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5. Rebuild with new kit
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6. Sync carburetors
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7. Reinstall and test
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---
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## 📋 Next Steps
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- [ ] **REMOVE SPARK PLUG AND INSPECT** (do this first!)
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- [ ] **TEST FOR SPARK** with spark plug grounded to engine
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- [ ] **CHECK FUEL FLOW** at carburetor
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- [ ] **INSPECT AIR FILTER** condition
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- [ ] **TEST BATTERY VOLTAGE**
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- [ ] Based on findings, proceed with appropriate repairs
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**CRITICAL:** Do NOT assume it's the carburetor until you've confirmed:
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1. ✅ Spark is present
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2. ✅ Fuel is reaching cylinders
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3. ✅ Air flow is good
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---
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## 📅 Session Log
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- **[2026-03-22 16:31]:** Issue reported - ATV cranks but won't start, suspected carburetor issue, battery consistently dies
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- **[2026-03-22 TBD]:** Next: Perform spark test and fuel delivery confirmation
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---
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## 📝 Notes
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- **Do NOT just rebuild carbs** without confirming spark and fuel first
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- **Old fuel is a common issue** - drain and replace with fresh gas
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- **Battery issue may be separate** - charging system could be failing
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- **Multiple issues possible** - weak battery + bad carbs + old fuel
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---
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## 📊 Success Criteria
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### Before Starting
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- [ ] Spark test performed
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- [ ] Fuel delivery confirmed
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- [ ] Battery condition assessed
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- [ ] Root cause identified
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### After Repair
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- [ ] Engine starts immediately
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- [ ] Runs smoothly at idle
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- [ ] Accelerates properly
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- [ ] No stalling or rough running
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- [ ] Battery holds charge
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### Verification Steps
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1. Start engine - should fire up within few cranks
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2. Let warm up - should idle smoothly
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3. Test throttle response - should accelerate without hesitation
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4. Check battery voltage after riding - should stay charged
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5. Test ride - no stalling, no misfires
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---
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## 🧪 Revision History
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| Date | Change |
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|------|--------|
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| 2026-03-22 16:31 | Initial issue documentation - crank no-start, suspected carb, battery issue |
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---
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## 🔗 See Also
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- [Main vehicle project README](../README.md)
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- [ISSUE_TEMPLATE.md](../ISSUE_TEMPLATE.md)
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Reference in New Issue
Block a user