Fuel Pump Priming Timer
for vehicles with
BOSCH L-Jetronic Fuel Injection
(Fully Assembled Module)

Product Use

This 12 VDC Timer Module is especially developed for Automotive use.
It is intended to be used on all vehicles with BOSCH L-Jetronic Fuel Injection System.

It is also used in OKA modular Fuel Injection System for Small Engines.

The 12 VDC Timer Module primes the Electronic Fuel Injection System (EFI) to full fuel pressure prior starting the engine, and this allows easy and instant starts no matter for how long the vehicle was parked or if it is hot or cold.

The BOSCH L-Jetronic Fuel Injection System as originally designed only switches on the Electric Fuel Pump once the Fuel Injection Control Unit senses "Air Flow" signal from the Air Flow Meter.

Also the BOSCH L-Jetronic Fuel Injection Systems Fuel System is designed to "hold" Fuel Pressure (usually at about 36 PSI) when the engine is turned off.

On older vehicles, or vehicles that have been parked for extended period of time, this Fuel Pressure is eventually "lost" and this makes the starting more difficult, especially at temperature extremes both hot or cold.

When "Ignition ON" signal at a typical automotive system voltage (10 VDC to 14.4 VDC) is applied to the 12 VDC Timer Module the Output is automatically turned ON for pre-set time interval through a high current Relay, and then goes OFF for as long as the "Ignition ON" signal is applied.

The 12 VDC Timer Module is used to provide power signal (12VDC +), which is used  to prime the fuel pump when Ignition switch is first turned ON and before the engine is cranked to be started.

There is Status Indicator LED located on the Module:

Red LED is ON when the Timer Module is operational.

The 12 VDC Timer Module contains five to seven second Electronic Timer which is directly connected to electro-mechanical Relay with N/O 20A power contacts.

Timing is shorter, but net less than 5 second, when the module is hot, and longer, but not longer than 7 seconds, when the module is cold.


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Fuel Pump Timer Module


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Fuel Pump Timer Module Schema


  1. Vbb = 12 VDC + Battery (connect through 20A fuse)  Brown/White
  2. Ign (Ignition ON Signal 12VDC +)  Yellow/Red
  3. OUT = To Fuel Pump +  Green/White
  4. GND (Common System Ground) Black

Product Specifications

Power Supply Voltage (min/max) VBB 8 / 18 V
OUTPUT Load current (max) IL 20 A
OUTPUT Signal Voltage (min/max) VOut VBB - 0.25 V DC
Power Consumption (ON) Pon 300 to 320 mW
Operating Temperature Ton  0 to 170
-18 to 76
Dimensions 108 x 53 x 30
Weight - Standard Module
Weight - HD Module


US $55.00 each - Standard Module

Standard Module is intended ONLY for installation on inside of the vehicle.
Standard Module is not suitable for high humidity or high vibration environment.
Fully potted HD Module, which is moisture and vibration proof is available for $75.00

Inquire for pricing and availability on purchases of 100 units or more


This Autotronic Module is used in OKA EFI System for Small Engines.

This Autotronic Module can be also used in any of the following vehicles OEM equipped with BOSCH L-Jetronic Fuel Injection:

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