1989 mercedes 300ce.new fuel pump,filter and relay,have fuel pressure at distribution block but nothing at delivery pipes to nossles when cranking any help ????alan 0221039734

First start with the basics check fuses relating to fuel and or injectors make sure there is voltage next look into your crank sensor usually if it fails the computer doesn't know you are trying to start the vehicle because the signal the sensor is supposed to give out to the computer is not there due to a faulty sensor once the computer senses the signal from the crank sensor then the computer will send a command to the injectors to start pulsating gas let me know how this turns out for you.
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have you change fuel filter ? check lines to make sure they arenot blocked..is pump working ,can hear it run ? do have enough fuel in it

Relay isnt usually the issue. The Klima relay should be on the passenger side behind the battery. Also another relay is under the screwed down cover behind the fuses. Normally the comprssor will not engage due to low pressure or bad pressure switch on the drier. Could also be the speed gage integrated to the compressor. Leak of the freon is normal but f it comes out as fast as it goes or just fast then the evap in the dash is most likely bad.

Checking for spark is really simple while fuel delivery is more complicated because of the the way it is metered for delivery. On VW's a fuel pump relay is used and a jumper cable connected to relay box. This controls the fuel pump to deliver fuel manually. With a fuel pressure gauge connected to the line from the pump continued withing the system, you assess whether you have correct fuel pressure, maintain it within a specif duration. Electronic fuel injectors do stick or stay open causing very poor or no start condition. Make sure you have fuel delivery since you are positive that spark is present.

Fuel filter is by the fuel pumps under rear passenger side of car. There is a plastic cover there. Also Look into your coil being bad, also wires, plugs cap and rotor. Ignition issues also can be caused by the OVP relay, the box with a fuse in it by the battery.

fuel pump relay

It sounds like a fuel delivery issue. Mercedes recommends replacing the fuel filter every 60k. If it has been longer than thast since the filter change start there. Fuel pump relays are another common problem on this era. They are located behind the battery. Remove the plastic cover and you will se 2 black relays( yours may have a mass relay if it is a 90 model year, it will have a plastic knob on top that you turn to the left to unsecure it) IT will say kickdown on it the climate control is the other relay and it will say klima. Look for signs of corrosion on the solder pins. If your fuel pump(located at the right rear) is very noisy when it operates I wouild recommend replacing it. During this era of Benz about the only way to diagnose this would be to run a bunch of fuel pressure tests and to drive vehicle with a meter on the relay and on the pump to see if the relay cuts out or the pump cuts out. I always recommend to do both pump and relay because they can cause one another to fail. good luck.

The fuel pump relay needs to be replaced. it is behind the battery and the fire wall.

I had the same problem, took to a benz dealer, it was the fuel pump relay, cost for repair $200.

sounds like you have a problem with your fuel pump relay. there is an underhood power distribution box, will be a plastic box with a lid on it. relay is in this box. it just unsnaps and a new one snaps in. the power distribution box might be on the fender or the firewall, but i'm sure you will find it.replace that relay and see what happens, think that will fix it. if it doesn't then i would suspect the wires to the relay. hope that helps