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Replaced both fuel pumps with new Bosch units. Replaced fuel pump relay which was shorted/burned with MB part. Engine cranks but won't start. What else might be the problem? What suggestions ? Thanks, Bill
 

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300CE fuel Pump Relay

It's a 1993 CE300 ID# ending in PB870604. Car does run if I load the MAF port with starter fluid but dies within a few seconds. How can I check power TO the relay base and power FROM relay to pumps? Relay and pumps are new. Thanks, Bill
 

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I wish relay testers were still a common thing at parts stores.

I need to check the relay used and then I can hopefully tell you how to test it with a DVOM or make a jumper to the two correct pins that would power up the pump.
 

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CE300 Fuel Pump

Thanks. It's a new MB relay MB#001-542-96-19 called a K27 in my MB manual. Surprisingly, that K27 number does not show up in my MB260/E300 wiring diagram which I am not sure to be the correct diagram. It's the only diagram that has the E300 designation. The manual is Mercedes Benz W124 1985-1995 which lists the 300E as being included. I'm lost! Do you know if this model has an inertia switch/fuel pump cutoff switch? Thanks, Bill
 

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I do not know if there is a safety inertia switch. I should have access to some MB docs before the weekend.
 

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I have what I think are the wiring diagrams. every time I try to export them as a PDF or .dxf file the drop
10% of their size. I am doing this in VA Ware on a Mac. I hope to get to a real Winderz machine as I have
been told the drivers for VM Ware Fusion are more than likely causing the problem.

From what I can tell in the circuit there is not an inertia switch, but it would not be the first time a wiring
diagram is wrong from a car maker.
 

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Are you sure the pumps are pumping? My guess is they still aren't getting power. Like that burnt relay makes me wonder wth caused it to burn so maybe something else is fried? Of course you checked the fuse right?
In situations like this where I cannot figure out wth is wrong I'll just run a new wire to feed whatever it is directly. At the very least you can do that to troubleshoot by feeding the pump(s) power and see if it starts.
The starting fluid was a good test, so at least you know it has spark and wants to run, it's just missing fuel.
 
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