Fuel pump differences?

[Druk]

Fired up the 107 after it's winter hibernation and after an initial easy start, it cut out. Traced it to a seized fuel pump. Replaced (temporarily?) with one from the tandem dual pump setup off a deceased W124 320e. This is a smaller dia pump from the standard. Car started easily and seems to run fine although haven't as yet had it out on the motorway at sustained speed. (K-jetronic injection)

Q? Is there a different pressure and/or flow from the smaller pump and will I damage something using it long term? I've got two of them and it would be a waste to go spend £200 on the correct item when not required.

 

[Number_Cruncher]

The pressure is set by the primary pressure regulator in the metering head, not by the pump.

As long as you have a healthy return flow of fuel to the tank, and the single motor doesn't run too hot, the setup will be OK.

 

[V12]

I agree. Luckily you have a 280, if it were a V8, you would need a double pump setup to have adequate petrol flow.

 

[Druk]

Thanks. Agreed 'lucky it's not a V8'; it would have been gone by now, can't stand the things.

1/ How would I determine if there is sufficient return flow to the tank?

2/ Would it help if I rigged the tandem setup complete from the 320? They run in series.

 

[Dieselman]

If the pump can't deliver enough flow the engine will start to stutter under high load, such as climbing a steep hill in high gear.