Kei Truck Won't Start: A Decision Tree (Cranks but No-Start, and Dead)
The short answer
If a kei truck cranks but won't fire, check in order: spark, then fuel pressure, then compression — each one cheaper and quicker to check than the next, and together they narrow the cause down fast. If it won't crank at all, the cause is almost always the battery, the starter circuit, or a safety switch, not the engine itself.
These engines are simple — three cylinders, minimal electronics compared to a modern car — and that simplicity cuts both ways. There are fewer things that can go wrong, which means a methodical check genuinely narrows a no-start problem down fast, often in about 20 minutes with basic tools. This page is that method.
There are two completely different problems hiding under “won’t start”: the engine cranks but doesn’t fire, or the engine doesn’t crank at all. Figure out which one you have first, because the diagnostic paths don’t overlap.
Path A: engine cranks but won’t fire
If the starter is turning the engine over but it never catches, work through these three checks in order — cheapest and quickest first.
1. Spark?
Remove a plug, ground it against the engine block, and crank while watching for spark. You’re looking for a fat, blue spark. Weak, orange, or no spark at all points to an ignition issue.
On the F6A and older Acty engines, check the distributor cap and plug leads specifically — these are the documented weak points for that generation, covered in more depth on the F6A distributor cap page. On the R06A and later K6A variants, the ignition is coil-on-plug, so a failed coil is the equivalent suspect.
Check at inspection
If you’re working on an Acty with intermittent gremlins — stalling and hard starts that come and go rather than a clean, consistent no-start — suspect the ECU capacitors first. That symptom pattern is different enough from a straightforward ignition fault that it’s worth ruling in before you start pulling plugs.
2. Fuel pressure?
If spark checks out, move to fuel. ⚠️ On the K6A, the reference spec is roughly 38-44 psi key-on and 31-36 psi running — treat these as K6A-specific reference values, since fuel pressure specs vary by engine, and verify against your model’s service manual rather than assuming they transfer directly to a different engine.
Common culprits behind low fuel pressure are a failed fuel pump relay, a weak fuel pump, or clogged injectors. On the Hijet specifically, a worn fuel pump is a known and common no-start cause — also check the model’s rust-prone fuel lines for leaks while you’re in there, covered on the Hijet cooling air-lock page alongside its other known quirks.
3. Compression?
If spark and fuel both check out and it still won’t fire, check compression. Low or zero compression points to a timing or internal issue.
On interference engines — the F6A, E07A, EF-series, and EN07 — the first thing to suspect is a snapped timing belt. Check the belt before assuming internal damage; see the age-and-import-condition cornerstone for why these specific engines are interference designs and why an unverified belt is treated as overdue. On the chain-driven K6A and R06A, a badly worn or skipped chain can also drop a cylinder — see the K6A timing chain rattle page for the warning signs that usually show up before it gets that far.
Green flag
A truck that passes spark, fuel, and compression cleanly but still has an intermittent no-start is unusual — and usually points to something that only shows up under specific conditions, like a marginal sensor or a heat-soak issue, rather than a hard fault. Document exactly when it happens (cold, hot, after sitting) before chasing parts.
Path B: dead, won’t crank at all
This is a different problem entirely — if the starter isn’t even trying to turn the engine over, work through this instead:
- Battery voltage below roughly 12.6V at rest → check the battery and its connections first. This is the most common cause by a wide margin and the cheapest to rule out.
- Starter doesn’t engage at all → check the starter relay and the neutral or clutch safety switch. Kei trucks commonly have a clutch start switch that must be fully depressed before the starter will engage — a switch that’s worn, misadjusted, or not being fully depressed will produce exactly this symptom.
- Starter spins but the engine doesn’t turn over → suspect the starter bendix or the ring gear teeth it engages with.
Walk away if…
Don’t keep cranking a starter that’s clearly not engaging properly — repeated attempts on a failing bendix or worn ring gear teeth can make the problem worse and turn a starter repair into a starter-and-flywheel repair.
If it still won’t fire after all three Path A checks
Suspect cam timing specifically — not just belt or chain condition, since timing can be off by a tooth even with an intact belt or chain — or a flooded condition from repeated failed start attempts. Both are less common than the first three checks, but they’re the right next step once spark, fuel, and compression have all come back clean.
Verdict
These engines reward a methodical approach precisely because they’re simple. The three-question sequence — spark, fuel, compression — genuinely narrows a cranks-but-won’t-start problem down in about 20 minutes with tools most owners already have. Don’t skip ahead to the expensive assumption before you’ve ruled out the cheap ones in order.
This page is owner-maintenance information to help you diagnose a no-start systematically. It is not a substitute for a qualified mechanic, especially once a check points toward something like a timing belt or internal engine issue.
Related pages
Affected engines & models
Frequently Asked Questions
- My kei truck cranks but won't start — where do I begin?
- Work through three checks in order, cheapest and quickest first: spark, then fuel pressure, then compression. This sequence narrows the cause down fast with basic tools, and you generally don't need to move to the next check until the previous one comes back normal.
- My Acty has intermittent stalls and hard starts that come and go — is this the same decision tree?
- Not exactly — that specific pattern, where symptoms move around and don't map to one clean cause, points toward ECU capacitor failure before anything else on the Acty. Check the ECU capacitors first rather than starting the spark/fuel/compression sequence from scratch.
- My Hijet won't start and makes a growling noise when cranking — what does that mean?
- A growling noise on cranking, paired with a no-start, points toward the fuel pump on the Hijet — a worn fuel pump is the documented leading no-start cause on this model. It's worth checking the fuel pump and the rust-prone fuel lines before working through the full decision tree.
- My Carry DA16T with a CVT won't move or goes into limp mode — is that a no-start issue?
- Not strictly — that's the CVT's temperature-protection (fail-safe) mode, usually caused by incorrect transmission fluid, not an engine no-start at all. If the engine itself starts and runs but the truck won't move properly, look at the CVT fluid rather than the ignition/fuel/compression sequence.
- My kei truck won't even crank — what should I check?
- That's a different problem from cranks-but-won't-fire. Check battery voltage first (you want at least roughly 12.6V at rest); if the starter doesn't engage at all, check the starter relay and the neutral or clutch safety switch, since kei trucks commonly have a clutch start switch that must be fully depressed to allow starting. If the starter spins but the engine doesn't turn over, suspect the starter bendix or ring gear.
- I've checked spark, fuel, and compression and they're all fine but it still won't fire — now what?
- At that point, suspect cam timing specifically (not just belt or chain condition — the timing could be off by a tooth even with an intact belt or chain) or a flooded condition. Both are less common than the first three checks but are the next things to rule out once the basic sequence comes back clean.
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