There are many fuel alternatives that one can take for BMW when swapping an M30 Engine. The good news is that swapping for an upgraded fuel pump is unnecessary, even when running a turbocharged E30 M30. For the imperative (minimum required), Enhanced, and superfluous styles of modification, I’ll help guide you toward the best method for each.
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Simply remove the fuel return and the fuel send from the M30 engine and hook it up to the E30 fuel return and fuel Send.
Please see the pictogram below for the overall fuel system on the M30. The picture also helps to explain where the fuel supply/return is located on the M30.
Looking from the driver’s side of the car the M30 fuel send line is on the right (red tape) and the return is on the left.
You can use the stock E30 fuel pump (unless it needs replacing), even good for turbo applications. I also think it’s a good time to replace the fuel filter as well.
As shown above in Figure 18, you can see where on the E30 the fuel send and return lines reside on the driver side frame rail where it comes up to the engine bay.
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Here, you can add a few options. This includes an adjustable fuel pressure regulator, replace the fuel filter, and add a larger Walbro 255 Fuel Pump.
The adjustable Fuel Pressure Regulator can be found at many outlets, but for a direct plug into the M30, I recommend the Bavauto Adjustable Fuel Pressure Regulator as shown below in Figure 19. Get more power and better throttle response from your BMW. This adjustable rising rate fuel pressure regulator enriches the fuel mixture as you accelerate to increase power and improve mid-range throttle response. Maintains stock fuel mixtures at idle.
The Walbro 255 Fuel Pump is a great enhancement for anybody looking to get more fuel reliably in all conditions. While the existing E30 fuel pump is adequate, it is old and likely tired. Therefore, I recommend putting in a Walbro 255 Fuel pump. Below in Figure 20 shows how it is adapted for the E30. At this stage, it is plug and play.
To install this, you must do the following, in order:
1. Remove the Existing E30 Fuel Pump & Fuel Level Sender.
2. Use the supplied hose & clamps to install on the E30 fuel pump holder.
3. Wire the positive to the Positive and the negative to Ground.
a. This may or may not include soldering, depending on the quality of your existing fuel pump housing.
Take note that this Walbro Fuel Pump will use more than your existing E30 fuse is prepared to handle. You are very unlikely go to over 90psi, so it is recommended to change the fuse rating on your E30 Fuel Pump Line from 7.5A to 15A as shown in . The existing wiring is setup to handle 15A as the wiring gauge is 16 Gauge.
The Fuel Filter is a simple in/out filter used to remove any debris or rust from the fuel lines before it goes into the sensitive pintels of your fuel injectors. The fuel Pump looks like that of Figure 21.
It’s a simple replacement involving a small flat head screwdriver & 8/10mm socket. On the E30, it is located IN FRONT OF the driver side rear wheel.
1. Remove the cowling that covers the fuel filter. This involves 8mm & 10mm socket
2. Remove the clamps holding the rubber fuel lines to the fuel filter. Use a flat head screwdriver.
3. Installation is the reverse or removal.
Finally, it might be a good idea to check the APR by getting an adjustable fuel pressure regulator. It goes in the fuel send line right before it hits the fuel rail. Check out the picture and you can see if you want to do this. If you plan on upgrading the car for tuning capability, no better time than now to put it in the line. I just put a tee in the fuel send line and routed it to a fuel pressure gauge (0-100psi). See Figure 22 below.