The Hisun Sector 750 side-by-side (SxS) is one of the most popular utility terrain vehicles (UTVs) on the market today. With its beefy 750cc V-twin engine churning out 60HP, dual-range transmission, locking differentials, and 3500-pound towing capacity, it’s built for rugged adventures. But like any machine, the Sector 750 can develop its share of problems.
So what are the most common Hisun Sector 750 issues owners need to watch out for, and how can you diagnose and fix these potential UTV problems?
In short – issues with the engine, electrical system, transmission, drivetrain, and suspension are among the most reported Sector 750 troubles. However, with some basic troubleshooting and mechanical skills, most common problems on the Sector 750 can be promptly addressed.
This in-depth post will uncover the most prevalent Hisun Sector 750 problems reported by owners, along with troubleshooting tips and repair solutions to get you back on the trail. We’ll cover:
- Common Hisun Sector 750 engine problems and how to diagnose and fix them
- Electrical issues that can leave your SxS dead in its tracks
- Transmission problems like slipping, hard shifting, and noise
- Drivetrain and suspension troubles
- Maintenance and preventative care
- When to seek professional Sector 750 service
So whether you already own a Hisun Sector 750 or are considering purchasing one, read on to learn how to handle its most common issues and keep your powerful UTV running in tip-top condition.
Table of Contents
Background on the Hisun Sector 750 UTV
Before diving into problems and fixes, let’s take a quick look at the Sector 750 and what makes this utility vehicle tick.
Introduced in 2014, the Hisun Sector 750 is one of the most popular models in the company’s SxS lineup to date. It’s built on a tubular steel frame and features:
- A 749cc 72-degree V-twin engine pumping out 60HP
- Electronic fuel injection (EFI)
- CVTech fully automatic CVT transmission with high, low, neutral, reverse
- True on-demand AWD and 4WD modes
- Hydraulic disc brakes
- Double A-arm independent suspension
- 3000 lb towing capacity and 1000 lb cargo bed capacity
It has enjoyable Power Steering, comfy bucket seating for driver and passenger, digital gauges, and sealed storage. The alloy wheels and Maxxis Bighorn tires provide good traction even on rough terrain.
With its responsive V-twin engine, rugged construction and versatile performance, it’s no wonder the Hisun Sector 750 has become a favorite workhorse UTV for farmers, ranchers, hunters and off-roading enthusiasts alike.
But even well-built side-by-sides like the Sector 750 can start exhibiting problems over time, especially if regular maintenance is skipped. So let’s look at some of the most common issues reported by owners and how to get them fixed.
Common Hisun Sector 750 Engine Problems and Repairs
The stout 60HP V-twin engine provides the motivation to get your UTV moving. But like any powerplant it can sometimes struggle with issues. Here are some of the most prevalent Hisun Sector 750 engine problems and how to troubleshoot them:
Overheating is one of the most reported engine troubles on the Sector 750. Typical causes include:
- Clogged radiator fins – Mud, debris and insects can congest the radiator cooling fins. Use compressed air to gently clean between the fins. Avoid high pressure washing which can bend fins.
- Faulty radiator cap – The cap needs to hold pressure to raise the coolant boiling point. Replace cap if old/cracked.
- Insufficient coolant – Low levels can cause overheating. Check for leaks. Top up with a 50/50 antifreeze/water mix.
- Failed water pump impeller – The plastic impeller can shear and reduce coolant flow. Replace water pump.
- Thermostat failure – Stuck closed thermostats prevent coolant flow to the radiator. Replace thermostat.
- Cooling system air pockets – Trapped air reduces coolant circulation. Bleed cooling system.
If overheating only occurs under load it could signify insufficient airflow to the radiator. Check for debris blocking airflow or a defective cooling fan.
Loss of Power
Lack of throttle response and diminished top speed are other common complaints:
- Clogged air filter – Replace filter immediately if excessively dirty.
- Fouled/damaged spark plugs – Inspect. Replace plugs if worn or heavily carbon fouled.
- Clogged fuel injectors – Run fuel injector cleaner additive through fuel system.
- Low engine compression – Perform compression test to pinpoint compression issues from worn piston rings, leaking head gasket, valves etc.
- Limp mode – The ECU may limit engine power to protect from damage if issues like overheating occur.
- ECU/sensor problems – Faulty electronics can affect performance. Scan ECU for trouble codes.
Be methodical isolating the source of power loss problems. Check easy things like air filter and plugs first before diving deeper.
Excessive Oil Consumption
Burning more than around 1 quart per 20 hours of operation indicates abnormal consumption. Causes include:
- Worn piston rings – Allows oil blow-by into combustion chamber. Inspect rings, cylinders for wear and glazing.
- Failed PCV system – Blocked crankcase vent hoses pressurize crankcase, pushing oil past seals. Inspect, clean/replace PCV components.
- Leaking seals/gaskets – Valve seals, timing cover, and rear main seal are potential leakage points. Replace worn seals and gaskets.
- Cracked engine case – Can be caused by overheating issues. Have inspected at machine shop.
Oil leaks are messy and potentially hazardous. Repair drips and weeping promptly. Always use correct weight/grade oil for operating conditions.
Blue smoke usually means oil is burning while white smoke points to water/coolant entering the combustion chamber:
- Worn valve seals/guides – Allows oil to leak past into cylinder. Replace seals, ream guides.
- Damaged piston rings – Pistons need proper ring seal for combustion pressure. Inspect piston/cylinders walls for scoring and glazing issues.
- Head gasket leak – Blown head gasket can allow coolant and oil to mix. Retorque head; replace gasket if needed.
- Cracked engine block/head – Can cause serious internal leaks. Have inspected at machine shop, pressure tested.
Smoking needs to be cured ASAP to avoid further engine damage. Identify smoking color and under what conditions it occurs to isolate root cause.
Some engine noise is normal, but knocking or tapping noises are more alarming:
- Excessive valve lash – Valves out of adjustment can cause tapping sound. Recheck/adjust valve lash clearance.
- Worn camshaft – Excessive cam lobe wear allows valves to close too late. Replace camshaft if worn.
- Low oil pressure – Can result in valve train noise on startup. Verify oil pressure. Change filter, check pump and relief valve.
- Piston slap – Noisy piston movement in the cylinder from excessive clearance. Inspect pistons/cylinders for wear and damage.
- Rod bearing failure – Knocking noise at higher RPMs. Check bearing clearances. Rebuild bottom end if bearings are worn out.
Mechanical knocking and tapping sounds demand prompt attention to avoid catastrophic failure. Isolate noise sources and repair.
Hard Starting/Stalling Issues
Difficult starting and random stalling can have several possible causes:
- Battery problems – Weak/defective battery struggles cranking the starter. Load test battery, recharge fully or replace if necessary.
- Loose/corroded connections – Poor electrical contact prevents proper starting system function. Clean terminals thoroughly.
- Faulty fuel pump – Pump may not build adequate fuel pressure for starting. Verify pump operation and pressure output.
- Clogged fuel filter – Restricted filter reduces fuel flow to injectors. Replace filter.
- Failed injectors – Clogged or leaking injectors disrupt fuel delivery. Test injector resistance and performance.
- Air leaks – Vacuum leaks mess with fuel mapping causing a lean condition. Check for cracked intake components.
- Ignition faults – Issues like bad plugs, faulty coil or CKP sensor can cause misfiring and stalling. Diagnose ignition parts.
Use basic diagnostic steps to methodically pinpoint no start and stalling causes. Bad gas or water in fuel are other potential culprits.
Lack of Top Speed
The Sector 750 is capable of over 60 MPH in high range when unrestricted. Lack of top speed can signify:
- Drive belt slipping – Glazed/worn belt loses traction. Replace belt, check pulleys for issues.
- Throttle restrictions – Sticking throttle body or bad TPS sensor can limit WOT. Check throttle operation and sensors.
- Engine issues – Compression loss, clogged air filter, bad gas etc affect power. See other engine sections.
- Speed limiter engaged – The ECU may activate top speed limiter function. Scan ECU for codes.
- Transmission problems – Improper shifting or worn components reduce top speed. See transmission section.
Safely test top speed in a wide open area once other causes are ruled out. Gearing, tire size and weight also impact max speed capability.
Diagnosing and Fixing Common Hisun Sector 750 Electrical Issues
Electrical problems can quickly ruin your off-road adventures. Here are some of the most common electrical issues on the Sector 750 and how to diagnose them:
Sector 750 Won’t Start Issues
If your UTV won’t turn over or start, focus on these key areas:
- Dead battery – Weak/faulty batteries fail to engage the starter. Load test battery, recharge fully or replace.
- Loose/dirty battery connections – Inspect terminals for corrosion and tightness. Clean thoroughly.
- Damaged starter solenoid – Bypassing the solenoid is a quick way to test. Tap solenoid case with a wrench to free contacts. Replace if faulty.
- Bad starter motor – Tap starter with a hammer while an assistant turns the key. If it temporarily engages, the motor is likely failing. Test and rebuild or replace starter.
- Blown main fuse – Key fuses protect electrical circuits. Check for continuity. Replace blown fuses.
- Faulty neutral safety switch – Machines must be in Park/Neutral to start. Jump switch temporarily as a test. Replace faulty safety switches.
- Security system issues – Machines with security systems need properly synced keys/fobs. Reprogram system components as needed.
Methodically test components to pinpoint no-start causes. Don’t keep cranking the starter motor without investigating, you can overheat and damage it.
Electrical Accessory Issues
Problems with accessories like power steering, lighting and gauges are also common:
- Blown fuses – Inspect all accessory circuit fuses. Replace blown fuses with correct amperage units.
- Damaged wiring – Inspect wiring harness thoroughly. Repair any chafed or cut wires. Clean oxidation off terminals.
- Ground faults – Clean ground points to chassis frame. Verify accessories have good ground connections.
- Faulty sensors – Many accessories use position, temperature and speed sensors. Test sensor continuity and resistance specs per service manual.
- Bad relay/solenoid – Test switches and relays using a multimeter. Replace defective units.
- ECU issues – The engine control module manages many systems. Scan ECU for diagnostic trouble codes and issues.
Electrical gremlins can be frustrating without a methodical diagnostic approach. Use wiring diagrams and a DVOM meter to isolate faults.
Intermittent Electrical Problems
With intermittent issues components work sometimes but fail at other times. Common causes include:
- Loose connections – Vibration can cause terminals to lose contact intermittently. Inspect connectors, clean and secure.
- Defective switch contacts – Bad ignition switch contacts can cause intermittent power loss. Test switches and replace if faulty.
- Defective ground – Corrosion on ground points can cause contact issues. Clean and test all grounds.
- Damaged wiring – Wires damaged from rubbing can short/open intermittently as they move. Inspect wiring closely.
- Voltage spikes – Bad voltage regulators or alternators can produce voltage spikes that damage components. Test charging system for issues.
- Contaminants – Mud, dirt, dust, moisture can all cause connection problems. Clean connections thoroughly.
Intermittent bugs take patience to isolate. Add dielectric grease to prevent future corrosion issues on terminals.
No Spark Issues
Lack of ignition spark will quickly halt any engine:
- Faulty emergency stop switch – Machines must have circuit continuity through this switch. Test function and continuity.
- Broken starter interrupter – This relay blocks spark during starting. Replace defective interrupter.
- Bad ignition coil – Coil converts 12V to thousands of volts for plugs. Test coil primary and secondary resistance specs per manual.
- Defective CKP sensor – This crank position sensor helps control ignition timing. Inspect sensor, test resistance values.
- Broken spark plug wires – Visually inspect plug caps, wires for cracking/broken conductors. Replace wire set if needed.
- Fouled/bad spark plugs – Inspect plugs. Replace per manufacturer interval or if excessively fouled.
No spark equals no start. Use spark tester lights to confirm ignition issues.
Diagnosing and Repairing Common Hisun Sector 750 Transmission Problems
The transmission takes some abuse when towing and climbing hills. Here are some prevalent transmission problems owners experience:
Transmission Slipping Issues
Clutch slipping results in loss of power and acceleration:
- Low clutch fluid level – Inspect reservoir level and condition. Top up with manufacturer specified fluid if low. Fix any leaks.
- Clutch worn out – The high-friction clutch plates can wear over time. Replace clutch kit with new steel and friction plates, springs as needed.
- Weak clutch springs – Upgrade to heavy duty clutch springs if slipping continues after replacing plates and fluid.
- Clutch contamination – Clutch components can get contaminated with metal shavings and debris. Inspect plates and magnet for contaminants during clutch replacement.
Test clutch engagement in high and low gears in an open area. Rebuild or replace the clutch assembly if slipping persists.
Transmission Shifting Problems
Difficulty getting transmission into gear points to issues like:
- Low transmission fluid level – Check reservoir level. Top up with manufacturer specified fluid.
- Damaged shift forks – Forks engage gears. Replace worn shift forks, inspect drum grooves.
- Bent shift rail/shaft – Forcefully shifting can bend components. Remove and inspect shift shafts and rails. Replace bent parts.
- Faulty shift detents – Worn detent springs and balls won’t properly engage gears. Replace detent components.
Erratic shifting behavior needs prompt diagnosis to avoid damaging transmission. Test engaging each gear with engine off to isolate hard shifting issues.
Transmission Noise Issues
Howling, grinding or whining noises from the transmission indicate problems:
- Bad bearings – Worn main shaft and other bearings create noise. Replace bearing kit throughout transmission.
- Damaged/worn gears – Pitted, cracked or misaligned gears cause grinding. Split cases and inspect all gears closely. Replace noisy gears.
- Insufficient lube – Low oil causes gear noise under load. Top up oil level. Use manufacturer specified lubricant.
- Drive belt debris – Belt dust and chunks can accumulate on clutch and gears. Clean all debris, replace worn belt if needed.
Unusual noise emerging from transmission area demands immediate investigation. Catching problems early greatly reduces repair costs.
Oil leaks create mess and lead to insufficient lube:
- Damaged seals – Oil can leak past worn output shaft seals and gaskets. Replace leaking seals and gaskets.
- Cracked housing – Severe leaks indicate a cracked case or transmission pan. Inspect closely, repair/weld housings as able or replace.
- Loose bolts – Ensure case bolts and fasteners are torqued to spec to prevent leaks.
Aggressively diagnose the source of any leaks right away. Keep areas clean to easily spot new leakage.
Common Hisun Sector 750 Drivetrain Problems
Issues with differentials, axles, and 4WD components can also leave you stranded:
- Insufficient lube – Low oil causes wear and noise. Maintain proper levels, change fluid regularly. Use manufacturer spec lube.
- Damaged gears/bearings – Cracked, pitted or misaligned gears create grinding noise. Split cases, inspect gears closely and replace as needed.
- Axle shaft issues – Broken or bent axle shafts are safety hazards needing replacement.
- Locker malfunction – Test differential locker engagement. Repair or replace malfunctioning locking mechanisms.
The drivelines take a beating traversing rugged terrain. Common problems include:
- Worn U-joints – Clicking noises on acceleration point to worn U-joints. Replace bad U-joints immediately.
- Damaged boots – Cracked CV joint boots allow dirt ingestion causing wear. Replace torn boots and inspect joints.
- Bent shafts – Impact damage can bend shafts. Check carefully for vibration and binding. Replace bent shafts.
- Loose hardware – Ensure driveshaft bolts are properly torqued. Check for missing bolts. Replace damaged bolts/nuts.
Listen for clicking noises and look for damaged boots. Catching driveline problems quickly reduces repair costs.
4WD System Troubles
4WD issues can leave you unable to shift into gear:
- Low actuator fluid – Check level window while cycling actuator. Top up with manufacturer specified fluid as needed.
- Leaking actuator seals – Replace seals if leaks are causing low fluid levels and pressure loss.
- Jammed actuator – Remove, inspect and clean components if unable to shift. May need actuator rebuild/replacement.
- Broken linkage – Linkages connect the 4WD selector to actuators mechanically. Inspect, repair/replace damaged linkage.
- Shifter problems – Ensure shifter assembly engages properly into each detent position. Repair/replace faulty components.
Cycle through 4WD high and low range modes during testing to confirm proper engagement.
Common Hisun Sector 750 Suspension Problems
Riding over rugged terrain takes a toll on shocks and suspension:
- Leaking shocks – Worn seals cause oil loss and bouncy handling. Replace shock seals or complete shock assemblies.
- Sagging springs – Weak coils allow chassis sinking. Install stiffer replacement springs.
- Worn ball joints – Clunking during cornering signals ruined ball joints. Replace upper and lower joints.
- Bent control arms – Impact damage can bend suspension links. Inspect closely, replace arms as needed.
- Loose hardware – Ensure all suspension hardware is tightened to manufacturer specs.
Listen and feel for clunks, knocking noises and wallowing handling. Address suspension issues promptly for safety and ride comfort.
Best Maintenance Practices for Hisun Sector 750 Reliability
While Sector 750s are quite reliable, regular maintenance is crucial for longevity and avoiding problems:
- Follow service schedule – Stick to factory recommendations for oil changes, filter replacement, fluid flushes, etc based on mileage and hours.
- Inspect frequently – Look for emerging issues like fluid leaks, loose bolts, damaged joints, fraying wires, etc before they cause breakdowns.
- Change filters – Replace air, oil and fuel filters at prescribed intervals to prevent engine issues and power loss.
- Flush systems – Transmission, brake, and cooling system flushes remove contaminants and refresh fluid properties.
- Check pressures – Verify engine compression, fuel system pressure, charging system output and other specs annually. Address low results immediately.
- Clean machine – Pressure wash and wipe down your Sector 750 regularly to remove corrosive mud, dust and grime before it damages components.
- Fix problems ASAP – Address any mechanical or electrical issues promptly to reduce chances of catastrophic failure down the road.
With diligent preventative maintenance and prompt diagnosis of emerging problems, your trusty Hisun Sector 750 UTV will provide years of rugged and reliable performance on the trails.
When to Seek Professional Sector 750 Service?
While routine maintenance and minor repairs can be handled in your garage, bigger issues require qualified UTV shop service and repair:
- Engine overhauls – Rebuilding worn-out engines with piston, ring, valve and bearing replacement/refurbishment.
- Transmission rebuilds – Refurbishing transmissions with new bearings, gears and seals.
- Major electrical faults – Diagnosing and correcting difficult gremlins like intermittent electrical problems.
- Damaged drivetrain – Repairing bent axles, replacing noisy differentials, and rebuilding 4WD actuators.
- Advanced computer diagnostics – Troubleshooting issues with ECUs, fuel injection, sensors and other electronics.
- Suspension rebuilds – Installing new ball joints, control arm bushings, shock seals and springs.
- Performance mods – Handling upgrades like exhaust, intakes, programmers, boosted power add-ons, etc.
Work with an experienced SxS repair shop that knows the Hisun Sector 750 inside and out. Properly diagnosed issues fixed right the first time reduces costs and downtime for your machine.
The Hisun Sector 750 is certainly not immune to problems, but most common issues can be resolved with methodical troubleshooting and mechanical skills. Reference this guide when problems pop up to help get your capable UTV back on the trails quickly. And most importantly, stick to prescribed maintenance schedules and inspections to catch problems early before they snowball into major failures down the road. Your Sector 750 will reward you with years of rugged and reliable fun. Ride on!