Stihl 028 AV Super (Troubleshooting Guide)
If your 028 AV Super will not start, do not buy parts yet. Check the stop switch, fuel, air filter, spark plug, and starting method first. Then test for spark and compression if needed. These steps help separate a simple fuel or flooding problem from a fault that needs repair, without relying on guesswork or unsafe carburetor adjustments.
You have pulled the starter cord again and again. The saw still will not catch, and your weekend work is waiting. Before, it feels like every possible part could be bad. After a few careful checks, you should know whether to focus on fuel, ignition, compression, or a safety issue.
I use the same rule on an older saw as on any small engine: test the simple causes first, and change one thing at a time. The 028 AV Super is an air-cooled, single-cylinder, two-stroke saw with about 51.5 cc of displacement. Its age makes careful inspection useful, but age alone does not prove which part has failed.
Equipment Setup and Safety Preparation
Start with a safe, controlled inspection before pulling the starter or removing parts. A chain can move unexpectedly, and fuel vapors can ignite. Work outdoors, away from flames and sparks, with the saw switched off and cool. Wear eye protection and gloves; use the model’s manual for procedures and specifications.
- Set the saw on firm ground. Engage the chain brake for starting, and use the manual’s cold- or warm-start steps. Do not drop-start the saw.
- Check the stop switch, throttle lockout, handles, chain catcher, brake, bar, chain tension, and visible fasteners.
- Keep the bar nose away from people and objects. The upper quadrant near the nose is the kickback zone. A chain brake reduces risk but does not make nose contact safe.
- Do not bypass a safety device to get the saw running.
If the chain moves while the saw idles, switch it off. Do not use the saw until the cause is corrected.
Confirm the saw and its fitted parts
Model identification matters when ordering parts or looking up settings. Older saws may have replacement bars, sprockets, carburetors, or other components. Read the saw’s model markings and the bar stamp instead of assuming every 028 AV Super has the same setup.
A common bar range is 16–20 inches, but use only a combination approved for the saw. Match chain pitch, gauge, drive-link count, and sprocket. Many setups use standard 3/8-inch pitch, not 3/8-inch low-profile; gauge may be .050 or .063 inch. Verify the actual parts before buying a chain.
Troubleshooting a Stihl 028 AV Super That Will Not Start
A no-start diagnosis separates fuel, spark, and compression problems. Begin with checks that take little time and do not alter settings. If a test points to a deeper engine or fuel-system fault, stop rather than trying random parts or carburetor turns.
Check the fuel and air first
Use fresh fuel mixed with two-stroke oil at the ratio specified by the saw’s manual and the oil maker. Do not assume 50:1 is right for every 028 manual or every oil. Never use straight gasoline. If the fuel is old, smells stale, or the mix is uncertain, drain it safely and refill with a known-correct mix.
Next, inspect the air filter. A filter packed with dust can limit airflow and make starting difficult. Clean it as the manual directs, or replace it if damaged. Check that the filter and cover fit correctly before trying again.
| What you observe | First check | What it may indicate |
|---|---|---|
| No response after repeated pulls | Stop switch, starting steps, fresh fuel | Incorrect start procedure, switch issue, or fuel problem |
| Plug is wet after starting attempts | Flooding and choke position | Too much fuel in the cylinder |
| Plug is dry after starting attempts | Fuel supply and carburetor inlet path | Fuel may not be reaching the cylinder |
| Saw fires, then dies | Fuel quality, filter, fuel line, tank vent | Restricted or inconsistent fuel supply |
| Saw runs but chain does not oil | Oil level, oil holes, bar groove | Blockage or oil-system fault |
A wet plug does not prove the carburetor is bad, and a dry plug does not prove it has failed. Treat both as clues, then test the next item.
Check the spark plug and ignition
With the engine off and cool, remove the plug and inspect it. A cracked insulator, heavy deposits, or a damaged electrode can prevent reliable ignition. Use the plug type and gap listed for this saw in its manual; do not guess at a gap or substitute a part based only on appearance.
For a spark check, use an approved spark tester and follow its instructions. Keep fuel away from the test area and do not hold the plug or lead by hand while cranking. No spark can come from the plug, lead, stop-switch circuit, or ignition module. A spark seen in open air does not always prove the ignition works under compression, so test carefully before buying a coil.
If the plug is wet, the saw may be flooded. Set the choke and throttle as the manual directs for a flooded engine. Do not keep pulling with the choke closed. If it remains flooded, let fuel vapors clear in a ventilated area, then follow the manual’s clearing procedure.
Consider compression and internal damage
Compression is the pressure the engine builds as the piston moves. Low compression can make a saw hard or impossible to start, even when fuel and spark are present. A compression gauge can help, but use the correct procedure and compare the result with reliable service information for this model. I would not apply a generic pressure cutoff to an older saw.
If the starter pulls unusually easily, or the saw has little response despite confirmed fuel and ignition, compression deserves attention. A shop or experienced mechanic can inspect the cylinder, piston, rings, and crankcase sealing. Do not keep running an engine suspected of seizure or internal damage.
If It Starts, Then Stalls, Races, or Runs Poorly
A saw that starts briefly has given you useful evidence, but it has not passed its checks. Look for a repeatable cause before adjusting the carburetor. A fuel restriction, dirty filter, air leak, or incorrect setting can produce similar symptoms, so symptom alone is not enough to name a failed part.
If it stalls when you open the throttle, check fuel freshness, filter condition, and fuel delivery before touching the carburetor. If it races or will not settle at idle, shut it off. An air leak or carburetor fault can cause a dangerous high idle. Do not keep running it to see whether the problem clears.
Carburetor settings must come from the correct service information for the fitted carburetor and saw. A commonly published reference is about 2,800 rpm at idle and 12,500 rpm at maximum unloaded speed, but these are not universal adjustment instructions. Confirm the exact specification and use a tachometer. Do not tune by ear, and do not use adjustment to hide a mechanical fault. If the chain moves at idle, stop and correct the problem.
Repair Examples: Use the Symptom to Choose the Next Test
These are diagnostic patterns, not proof that every saw with the same symptom has the same fault. They show how I narrow the checks without replacing parts at random.
- Wet plug after many pulls: Stop repeated attempts and check whether the choke was left on. Follow the manual’s flooded-start procedure, then inspect the plug. If it floods again during a correct start, test fuel and carburetor operation rather than assuming the plug is the cause.
- Fires once, then stops: Confirm fresh, correctly mixed fuel and a clean air filter. If those are sound, check the fuel path and tank vent using the manual’s procedure. A brief fire alone does not identify which fuel-system part is at fault.
- No spark at the tester: Confirm the tester is connected correctly, then inspect the plug, lead, stop switch, and wiring. Replace a component only when testing or inspection supports that decision.
- Runs but does not cut well: Stop and inspect chain sharpness, tension, and bar oiling. A dull or mismatched chain can load the saw. It is not a reason to force the saw through wood or raise engine speed.
The useful result is a testable next step, not a guessed diagnosis. Record what you changed and what happened.
Maintenance, Sharpening, and Carburetor Checks
Routine checks help prevent a simple maintenance issue from looking like an engine failure. With the saw off, inspect the air-filter area, bar groove, oil holes, sprocket cover, and cooling-air openings. Use bar-and-chain oil, and confirm oil delivery by the manual’s approved method. If it fails to oil, stop cutting and clear or repair the system.
Keep the chain sharp and tensioned as directed by the manual. Set depth gauges, also called rakers, to the chain maker’s specification; about 0.025 inch (0.65 mm) is common, but chain type matters. Do not force a dull chain through wood. Hard or dirty wood calls for a sharp chain and controlled feed, not a different chain specification.
A 028 AV Super that still will not start after fuel, air, plug, and spark checks may need service beyond basic cleaning. Carburetor work, air-leak testing, and internal engine checks require the right tools and model-specific information. A qualified repairer may cost more than a plug, but a confirmed diagnosis can cost less than buying several parts that do not solve the fault.
Storage and Seasonal Care
Storage problems often begin with fuel left in the saw or tank. Follow the manual’s fuel-storage instructions, keep fuel fresh, and store the saw in a safe, dry place away from ignition sources. Before the next use, inspect the saw again rather than assuming storage left it ready.
After use, switch the engine off, let it cool, and clean the filter area, bar groove, oil holes, sprocket cover, and cooling openings. Check the chain and bar for damage. If a fault returns, note whether it occurs cold, warm, at idle, or under load; that detail can help isolate the cause.
Frequently Asked Questions
What fuel mix does the 028 AV Super use?
Use the ratio stated in the correct saw manual and approved by the two-stroke oil maker. Do not assume 50:1 applies to every manual or oil. Never run straight gasoline.
Why will my 028 AV Super not start after many pulls?
Check the start procedure, stop switch, fuel freshness, air filter, and spark plug. A wet plug may point to flooding; a dry plug may point to fuel not reaching the cylinder. Test before replacing parts.
How can I tell if the saw is flooded?
A wet spark plug after repeated start attempts is a useful clue. Follow the manual’s flooded-start procedure, clear vapors safely, and avoid repeated pulls with the choke closed.
What should I check if there is no spark?
Use an approved spark tester. Check the plug, lead, stop-switch circuit, and wiring before condemning the ignition module. Follow safe testing steps and keep fuel vapors away.
What bar and chain fit this saw?
Confirm the saw’s approved setup and match pitch, gauge, drive-link count, and sprocket. Common setups use standard 3/8-inch pitch, with .050- or .063-inch gauge, but check the fitted bar stamp.
What idle speed should the 028 AV Super have?
A commonly published reference is about 2,800 rpm, but confirm the exact service specification for the saw and fitted carburetor. Use a tachometer; do not tune by ear. If the chain moves at idle, stop.
Why does the saw start and then stall?
Possible causes include stale fuel, a dirty filter, restricted fuel delivery, or a carburetor or air-leak issue. Check the simple items first. The symptom alone does not identify the failed part.
Why is my saw not oiling the chain?
Check the oil level, bar groove, and oil holes, then use the manual’s test procedure. Stop cutting until oil delivery is restored, because a dry chain and bar can be damaged.
When should I take the saw to a repair shop?
Seek service if spark, fuel, and basic maintenance checks do not find the cause, or if compression seems low, the saw races, or it continues to flood. Avoid running a saw with suspected internal damage or an air leak.
(This article was written by one of our staff writers, Robert Callahan. Visit our Meet the Team page.)
