Mercedes 300 E 1987 does not start

In parts:

The first thing we are going to look at is the gasoline pump drive when putting the contact and during the starting phase, if the contact of the pump between two and five seconds is heard, it means that the pump works. To see if the gasoline pump works during the start, it is enough to touch it while the engine is turned to start, the vibration of it will be noticed when working.

The pump pressure upon reaching the regulator must be between 5.3 and 5.5 bar. This test must be done with the engine stopped, terminals are bridged 30 and 87 of the taquimetric relay. The pump flow must be around two liters per minute.

To check the cold starting injector drive: it is located in the intake manifold. Without taking it out, it will be checked with a voltmeter if it reaches current, this injector only works while the start for a period of between 8 and 15 seconds, then despite continuing to turn with the start, the injector should not receive current.

If the cold starting injector does not reach current, the cause must be sought in the timed thermocontact.

To check the timed thermocontact: it is located in the cylinder head. With an ohmmeter you have to disconnect the plug and measure resistance between each of the two terminals of the thermocontact and mass. In one of them there must be continuity and in the other a resistance of between 25 to 80 ohms. If the resistance terminal is fed with battery voltage, mass continuity will be interrupted in the other terminal after 8 to 15 seconds.

To check the additional air valve: it is located near the probe plate and the gas butterfly, in the intake manifold to check it, you have to disassemble the tubes and look through them to see if the sheet is completely open with the cold engine and the contact removed. To measure the resistance, the plug must be disconnected and measured with an ohmmeter, the resistance value must be between 14 and 21 ohms and check if it reaches current you have to bridge terminals 30 and 87 of the taquimetric relay and measure tension in the connector of the aforementioned valve. After about 4 or 5 minutes, the bimetallic sheet should have completely closed by obtaining the air passage through the tubes.

Mechanical checks:

Adjustment and focused of the probe plate: it is enough to remove the air filter and look below, apart from being centered, by pressing it with the finger, it must have some resistance and show how \ "chillan \" the injectors. The course of the dish must be homogeneous at all times and after moving it several times, the resistance to movement will disappear due to the pressure drop in the regulator.

Pressures:

Apart from the pump pressure that I have already told you how you look, in the K Jotronic system (which seems to me that it is not the one that carries that car) you have to also look at the pressure of the regulator of the heating phase. This regulator is screwed on the left side of the motor block, below, next to the steering box.

The pressure of this regulator must be between 0.8 and 1.2 cold bars and when it reaches operating temperature, it must be around 3.5 bars. If empty in the tube that communicates the regulator with the gas butterfly, the regulation pressure be the temperature will fall to 0.5 bar (which produces an automatic enrichment of the mixture when accelerating).
To verify the current arrival to the regulator connector of the heating phase, the 30 and 87 terminals of the taquimetric relay must be bridged. And to measure resistance, the regulator plug must be disconnected and measured with an ohometer, the resistance value must be between 20 and 30 ohms.

Anyway, I believe that this Mercedes does not carry this regulator, but has a regulator attached to the distributor dosing and that regulator is controlled at all times by the switchboard (KE Jetronic System).

In the KE Jotronic system, the additional air box is replaced by an electromagnetic actuator controlled by the switchboard so that only electrical resistance can be measured between the actuator terminals to verify that the electroman winding is not burned or broken.

All the best.

Thank you megabeat_1, you are like a self -hahaha, are all that they tell me and if you leave the car I swear that I invite you to the party.