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Bmw 733I Cold Start Fuel Injectors

Bmw 733I Cold start fuel injectors

Starting at $286.95, AutoBuffy stocks 1 cold start fuel injectors from URO. The cold start injector delivers an extra pulse of fuel during cold cranking to help the engine fire quickly in low temperatures. When it fails or leaks, cold-weather starting becomes difficult and fuel economy or emissions may suffer.

Signs your Bmw 733I needs a new cold start fuel injector

  • Hard to start or extended cranking required when the engine is cold, especially in temperatures below 40°F
  • Engine fires but immediately stalls before the idle stabilizes on first cold start of the day
  • Rough, stumbling idle for the first minute of operation that smooths out once the engine warms up
  • Raw fuel smell from the intake manifold or engine bay, indicating the injector is leaking when not commanded open
  • Black smoke from the exhaust on initial startup due to an injector stuck open flooding the manifold
  • Check engine light with codes related to fuel trim, misfires, or injector circuit faults present at cold startup

Which cold start fuel injector should you buy for your Bmw 733I?

The cold start injector is a single, dedicated injector separate from the main fuel injector set, so fitment to the exact intake manifold port is critical. Your main decision is between an OEM-specification replacement and a remanufactured unit, and whether you want a new or rebuilt injector given how infrequently this component cycles.

OEM-Equivalent New Injector
Best for
Owners who want a direct drop-in with no adjustment and maximum longevity
What you get
Factory-matched flow rate, spray pattern, and connector — installs without modification
Remanufactured / Rebuilt Injector
Best for
Budget-conscious DIYers on an older Bmw 733I where a new unit costs significantly more
What you get
Professionally cleaned, flow-tested, and resealed injector at a lower price point; quality varies by rebuilder
Fuel Injector with Seal/O-ring Kit
Best for
Anyone whose injector body is intact but leaking at the manifold or fuel rail connection
What you get
New injector plus all seals and insulators needed to reseal both ends — avoids leak recurrence
Cold Start Injector Delete / Bypass Kit
Best for
Performance builds or owners of high-mileage vehicles who have upgraded to individual port injectors or a standalone ECU
What you get
Blocks off the manifold port cleanly; appropriate only when the ECU cold-start enrichment is handled another way

Cold start fuel injectors brands we stock for your Bmw 733I

URO
1 option · from $286.95

Replacing the cold start fuel injector on a Bmw 733I

Moderate⏱ 45 minutes – 1.5 hoursMultimeter (for pre-removal electrical testing)Fuel line disconnect tool or small flathead screwdriverSocket set and extensionsNeedle-nose pliers (for hose clamps or retaining clips)Clean rags and a small fuel catch container

Begin by relieving fuel system pressure and disconnecting the battery, then unplug the injector's electrical connector and disconnect the small fuel supply line. The injector is typically held to the manifold by one or two screws or a retaining bracket — remove those, then pull the injector straight out and replace all O-rings with the new ones included in the kit before installing the replacement. Reconnect the fuel line and electrical connector, cycle the ignition a few times to repressurize the system, and inspect for leaks before starting the engine.

Frequently asked questions

How much does it cost to replace cold start fuel injectors on a Bmw 733I?
Parts start at $286.95 on AutoBuffy. Labor is typically modest because the cold start injector is externally mounted on the intake manifold and accessible without removing major components. Total out-of-pocket cost at a shop will depend on your local labor rate, but the job is straightforward enough that many owners do it themselves.
Can I drive my Bmw 733I with a bad cold start fuel injector?
Yes, with caveats. If the injector has simply stopped functioning, your Bmw 733I will be difficult to start in cold weather but may run normally once warm. If the injector is stuck open, raw fuel can wash cylinder walls and dilute engine oil, making continued driving a risk to engine health until it is replaced.
How do I test the cold start injector on my Bmw 733I before replacing it?
Disconnect the electrical connector and use a multimeter to check the injector's resistance against the spec in your service manual — an open or short circuit confirms electrical failure. You can also apply 12V directly during cranking and listen for a click, or remove it and observe spray pattern into a container. A leaking injector can be confirmed by inspecting for fuel in the intake manifold after a long soak.
What causes a cold start fuel injector to fail on a Bmw 733I?
The most common causes are a clogged nozzle from long-term fuel varnish deposits, a failed solenoid coil that stops the valve from opening, and deteriorated O-rings or seals that allow external fuel leaks. The thermo-time switch that controls the injector can also fail, causing the injector to run too long and flood the engine even when warm.
Is the cold start injector the same as the regular fuel injectors on a Bmw 733I?
No. The cold start injector is a single, separately controlled injector mounted directly on the intake manifold or air intake plenum. It is only activated during cold cranking by a thermo-time switch, while the main port or throttle-body injectors handle normal fueling across all operating conditions. They are not interchangeable in most applications.
How long does a cold start fuel injector last on a Bmw 733I?
Because it only operates briefly during cold starts, the cold start injector typically outlasts main fuel injectors in terms of duty cycles. Failures are more often caused by age-related seal degradation, fuel varnish buildup from extended storage, or electrical coil breakdown rather than wear from high use. Many last the life of the vehicle on well-maintained engines.

Shop cold start fuel injectors by year for the Bmw 733I

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