E36 fuel pump query

[danieljames]

Hi fanatics. my car just died on me last night and after some testing I've diagnosed it as the fuel pump. I understand the standard fuel pump pumps at 3.5 bar. I intend getting a cheapie so long until I can source one from BMW or a decent aftermarket one. My question though, will getting one that pumps at 3 bar cause any problems on the fuelING side or will I just have a drop in performance?

 

[Major]

Pressure is determined by the fuel pressure regulator not the pump, the pump pressurises the line until the regulator starts to bleed fuel back to the fuel tank. This pressure is 3.5bar with no vacuum on the FPR. Are you sure the pump is only capable of 3bar, or does it only provide flow ratings for 3bar?

 

[danieljames]

Interesting. To be honest I cannot answer your question. When I called the spare shop they mentioned that it's a 3 bar pump. I'm going tomorrow so I'll be able to check which it is. Although logic tells me that the "rating provided" will be pumping capability.

 

[Major]

If the pump isn't rated for anything other than 3 bar, I don't think you should try it. Flow decreases with increased fuel pressure because the pump has to work harder. If your pump isn't rated for 3.5bar, it might be that it gets too hot, draws too much current, or flows worse at any higher pressure. I wouldn't take the chance.

 

[danieljames]

Thanks boet. Ur advice is really appreciated. Big ups for the speedy response

 

[Major]

Did you take a look at that pump today?

 

[danieljames]

Hi boet. Got a replacement pump for the now. Cheapie brand unfortunately. 3.5 bar. Atleast she's running again. What brand would u recommend for a replacement?

 

[Major]

Honestly if you just want a stock replacement go OEM, I think they're Siemens/VDO if you don't want to go through the stealers and can find it somewhere else. Otherwise upgrade your fuel pump to a Walbro/Aeromotive unit, as well as your fuel pressure regulator in case your stock one is on it's way out. Although you might be wasting your money if you don't plan on big power in the future.

 

[danieljames]

The biggest plans for my car would probably be a b30 conversion and i'm sire the stock unit should be able to handle that. Thanks for all the help Major. Big ups