Mercedes R107 fuel pump relay+first start in years

In this is video we attempt to start our 1975 Mercedes 280SL, which we’ve been restoring for the last year. This car has the earlier D-Jetronic fuel injection system and a low pressure Bosch fuel pump. The video shows how to bridge the fuel pump relay and also where to get a new D-Jetronic fuel pump should you need one.

[@takeaflight]

Thanks

[@MikesMercsandothercars]

My pleasure. Mike

[@markbuck7082]

Grest video

[@MikesMercsandothercars]

Thanks...getting ever closer to getting this baby driving. Mike

[@jonnybigpotato4263]

Another interesting video Mike, thanks. Inspired by your videos I have my 450SLC injection system apart now having noticed the hoses were cracking. Injectors all sent off for a refresh and I have all the plumbing for the front. But I was at an event last weekend for my other car (Citroen) and comparing what their injection systems were like and Iwondered on the D Jetronic fuel pump question whether just a generic pump (eg Facet) could be used with a fuel regulator to get the pressure at the rail low enough. I saw that set up on someone’s Citroen (albeit a carburetor car) and just wondered whether you had a view? Not that my pump has an issue at the moment, it just needs all the plumbing replacing but it would be helpful from a spare viewpoint.

[@MikesMercsandothercars]

Thanks for your comment. That arrangement would definitely work...but remember that the original D Jetronic pump has a check valve in the pump to filter that is suppose to maintain fuel pressure when you stop the engine. I think (but I'm not sure) that there is also an over pressure mechanism within the pump that limits the flow of fuel if the pressure gets above 3 bar. I'm intrigues to see if the Nissan 280Z pump arrives form USA and if it is correct. Mike

[@Ghost0104]

Hey Mike I’m in need of ur help my car has been sitting over 10 years now🙏🏽🙏🏽🙏🏽🙏🏽

[@MikesMercsandothercars]

Hi - I am no expert but just drop me a comment here with what you need and I will try to help. What make model and year is the car? Mike

[@sljgroup3229]

Mike I changed my 2 rubber O rings on my fuel pump car was running great before I changed the O rings put everything back went to turn on key did not here the fuel pump come on went and checked not power to pump any thoughts...fuses look good cant image the relay is bad any thought 73 450 sl

[@MikesMercsandothercars]

Hi - sorry to hear you have a problem. That is weird. I seem to recall having a similar problem when I did the fuel pump video. Tested everything at home, put it all back on the car...and then nothing.. I think (but I could be wrong), I cured the issue by priming the pump eg getting it to run by lifting the canister of fuel higher up. Before we go any further....I am assuming you connected the +ve and -ve terminals on the pump up the right way. Stupid question I know but its worth checking. If the pump is on the car, I would be tempted to discount the rubber hose from the pump outlet and aim it into a canister. Then I would disconnect the existing electrical connections from the pump and run a couple of wires directly from the battery to the pump. It is better to remove the battery from the car and use jumper cables to do this. If you accidentally touch the positive of the battery to the chassis, there is a chance you could fry the ECU or ignition control module. Does the pump run and pump fuel in this configuration. If so, put it all back together and see if it now runs with the key. Mike

[@sljgroup3229]

Mike thanks I did connect the pump on the 73 the wires can only go on the fuel pump one way. There are different sizes eyelets for each wire it can only go on each specific post on the pump. It is odd it was running fine I disconnected the battery before starting and now no power getting back to the pump. The battery shows 12 volts but when I turn the key to the 2nd position should have power for a second at the pump before the motor starts but put a multimeter on the lead going to pump no power.

[@sljgroup3229]

Sorry I ment disconnected the battery before starting the project.

[@sljgroup3229]

I think this must be an electrical issue....I also check the fuses they are good need to test the relays

[@sljgroup3229]

May have to jump the relay to see if pump works