HELP Fuel Pump Relay EKP/Engine Wiring Schematic

[sapote]

You are clearly not reading my posts, I posted my sources in post #31.....

George, I had read your post and I had said that I didn't have access to the training document. Just want to see the full section or pages where it describes the fuel pump PWM feature. Can you post the copy of the pages?

[George Hill]

Maybe, but I doubt the logic. I don't think there is any gas bubbles of fuel vapor in the pressurized fuel, as if there is, then the injectors cannot reliably meter the amount of injected fuel for a proper mixture. Especially at 72 psi it's not easy to have vapor.
The fuel delivery system is an sealed air tight system, and so even with more vapor formed in the tank, none of this is released into the atmosphere. Vapor due to the fuel being moved with engine running is nothing compare to when car parked under the hot sun.

I still am interested to see the source information of the PWM controlled fuel pump.

You are clearly not reading my posts, I posted my sources in post #31... I am done with this until Lou posts whether or not the EKPS fixed his car...

[sapote]

My thought is that less fuel pump speed means less fuel is being moved. Less fuel being moved means less fuel temp and less vapor, less vapor that now has to be collected and dealt with (i.e. less emissions).

Maybe, but I doubt the logic. I don't think there is any gas bubbles of fuel vapor in the pressurized fuel, as if there is, then the injectors cannot reliably meter the amount of injected fuel for a proper mixture. Especially at 72 psi it's not easy to have vapor.
The fuel delivery system is an sealed air tight system, and so even with more vapor formed in the tank, none of this is released into the atmosphere. Vapor due to the fuel being moved with engine running is nothing compare to when car parked under the hot sun.

I still am interested to see the source information of the PWM controlled fuel pump.

[George Hill]

Why do you think I was trolling? Who said that the relay was near the fuel or onside the tank? Fuel can leak and flamable vapor, and I was saying perhaps the US DOT required the relay to be semiconductor to avoid generating sparks. As about PWM or not, what I know from TIS is that it mentions nothing about PWM in the system description. I asked for your source of the PWM information as I don't have access to BMW MS S54 Training manual. If I called someone's wrong, or trolling, I will provide a readable or accessible source to prove it, not just saying or quoting it by myself.

Because whether the relay is in the trunk or cabin its no more exposed to fuel vapor than any other relay in those areas.

Blame the TIS as it listed for the Coupe, see pic below:

TIS is notoriously inconsistent unless you physically identify a car. When you manually select a car by its features (or even VIN) lots of time it is missing info or outright incorrect. The pic clearly shows its inside the cab because of the speaker and the white dot over the roof of the car in the lower left.

I don't think the pump PWM control is for emission reasons, as the DME already uses PWM to control the injector injection duration which directly affects the combustion mixture. So I do think PWM control the pump speed -- if it is true -- is to save power: use less pumping energy for low fuel demand at low rpm or idle.

My thought is that less fuel pump speed means less fuel is being moved. Less fuel being moved means less fuel temp and less vapor, less vapor that now has to be collected and dealt with (i.e. less emissions).

[sapote]

I can't decide if you are trolling or not... the EKPS and FP relay are both located inside the passenger compartment, they are nowhere near the fuel itself.

Why do you think I was trolling? Who said that the relay was near the fuel or onside the tank? Fuel can leak and flamable vapor, and I was saying perhaps the US DOT required the relay to be semiconductor to avoid generating sparks. As about PWM or not, what I know from TIS is that it mentions nothing about PWM in the system description. I asked for your source of the PWM information as I don't have access to BMW MS S54 Training manual. If I called someone's wrong, or trolling, I will provide a readable or accessible source to prove it, not just saying or quoting it by myself.

You literally posted a picture of the location for convertible which is behind the RR "door" panel

Blame the TIS as it listed for the Coupe, see pic below:

OK... well here's how it works. The pump on US cars is PWM controlled by the EKPS, Euro cars have a plain jane relay ******(I imagine this is for emissions reasons, tougher standards over here)******,

I don't think the pump PWM control is for emission reasons, as the DME already uses PWM to control the injector injection duration which directly affects the combustion mixture. So I do think PWM control the pump speed -- if it is true -- is to save power: use less pumping energy for low fuel demand at low rpm or idle.

[George Hill]

OK... well here's how it works. The pump on US cars is PWM controlled by the EKPS, Euro cars have a plain jane relay ******(I imagine this is for emissions reasons, tougher standards over here)******, I just can't recall if the DME sends a PWM signal to the EKPS or not.

I can't decide if you are trolling or not... the EKPS and FP relay are both located inside the passenger compartment, they are nowhere near the fuel itself.

Continuing on as others reading may be interested, this is from the *****BMW MS S54 Training manual:******

"The fuel ....

BMW Tis says US relay is in the trunk and not passenger compartment. I'm interested to know more about PWM controlled fuel pump as you said. Could you provide the source of your information? Also, how does the DME control the European M3 mechanical pump relay with PWM, as I don't think a mechanical relay could respond to the 100 Hz PWM, and it would make a lot of clicking noise too? Unless the PWM pump speed control is only for US cars, then why such a wonderful feature was left out for EU cars?



Tis didn't say anything about PWM controlled fuel pump:

You literally posted a picture of the location for convertible which is behind the RR "door" panel, the coupe is located in the trunk. Are you even reading my posts?

The DME has two fuel pump outputs, one is PWM and goes to the EKPS on US cars (X60002 pin #11) the other is to ground the fuel pump relay coil on EU cars and all non-m us E46 cars (X60004 pin #10). ***Because of this you don't have to make any changes to the fuel pump system when doing a S54 swap into a Non-M E46 chassis.

[sapote]

I can't decide if you are trolling or not... the EKPS and FP relay are both located inside the passenger compartment

BMW Tis says US relay is in the trunk and not passenger compartment. I'm interested to know more about PWM controlled fuel pump as you said. Could you provide the source of your information? Also, how does the DME control the European M3 mechanical pump relay with PWM, as I don't think a mechanical relay could respond to the 100 Hz PWM, and it would make a lot of clicking noise too? Unless the PWM pump speed control is only for US cars, then why such a wonderful feature was left out for EU cars?



Tis didn't say anything about PWM controlled fuel pump:

[George Hill]

I believe the EKPS is just a semiconductor relay as oppose to mechanical relay used outside US. One reason I can think up is using electronic relay has no potential of generating sparks by the breaker point, which could cause an explosion in highly combustible gas. Electronic relay can be operated just like the old mechanical relay, not PWM control signal needed. The only reason to use PWM control is when it needs to vary the variables, such as speed (radiator fan), pressure, flow rate (cabin heater coolant).

I can't decide if you are trolling or not... the EKPS and FP relay are both located inside the passenger compartment, they are nowhere near the fuel itself.

Continuing on as others reading may be interested, this is from the BMW MS S54 Training manual:

"The fuel pump supplies fuel when it receives operating voltage from the fuel pump module (EKPS). The DME relay supplies voltage to the EKPS (M3- located in the trunk above the RR wheel well, Vert - behind the RR interior trim panel).

The DME controls the activation of the fuel pump module. After the ignition is switch ON, the DME provides voltage for the EKPS and the voltage is maintained (PWM) with the presence of the engine speed signal.

The high output fuel pump is utilized to match the fuel supply demands of the S54 engine (5 bar). The DME will cycle the voltage signal (0-120HZ) to the EKPS. The EKPS will cycle the voltage to the pump (to reduce the speed). The fuel pump will operate at low speed during idle and part load. The pump will run at full speed during start-up (approx 20 sec) and full load.

The power to the EKPS will be switched off in the event of an airbag activation. The MRS III control module will signal the DME over the K-Bus and CAN bus for this purpose."

[sapote]

I believe the EKPS is just a semiconductor relay as oppose to mechanical relay used outside US. One reason I can think up is using electronic relay has no potential of generating sparks by the breaker point, which could cause an explosion in highly combustible gas. Electronic relay can be operated just like the old mechanical relay, not PWM control signal needed. The only reason to use PWM control is when it needs to vary the variables, such as speed (radiator fan), pressure, flow rate (cabin heater coolant).

[George Hill]

Don't think the pump needs to be modulated with PWM control as there is no reason for doing so. Pump already has pressure regulator. I would make more sense to have a pressure feedback sensor signal to the DME then it could control the pump speed to regulate the pressure.

OK... well here's how it works. The pump on US cars is PWM controlled by the EKPS, Euro cars have a plain jane relay (I imagine this is for emissions reasons, tougher standards over here), I just can't recall if the DME sends a PWM signal to the EKPS or not.

I'm not saying the DME isn't fried, I'm just saying that my experience points to a bad EKPS. I'm not sure why it takes out the EKPS, maybe the coils and fuel pump control share some internal circuit or what not but we'll know soon enough.

[sapote]

Just to add to the sample pool, I also forgot the coil pack ground once and the EKPS was what ended up causing my crank but no start. It also blew out the relay for the A/C.

-Ted

When the 15Kv has no path to discharge, it will zap to anything that have a path to the ground, direct or indirect, and damaged them. This cable is easily overlooked when we're excited to start the engine up after the valve cover is closed.

[sapote]

Off the top of my head, IIRC the DME pulse width modulates the EKPS so checking voltage with a DVOM isn't going to be very accurate. I'll send you a EKPS if you want to try it, send me a PM.

Don't think the pump needs to be modulated with PWM control as there is no reason for doing so. Pump already has pressure regulator. I would make more sense to have a pressure feedback sensor signal to the DME then it could control the pump speed to regulate the pressure.

[t3ddftw]

Just to add to the sample pool, I also forgot the coil pack ground once and the EKPS was what ended up causing my crank but no start. It also blew out the relay for the A/C.

-Ted

[George Hill]

Off the top of my head, IIRC the DME pulse width modulates the EKPS so checking voltage with a DVOM isn't going to be very accurate. I'll send you a EKPS if you want to try it, send me a PM.

[sapote]

I just measured the voltage with the relay disconnected and I see 0.01V at the EKP pin 1. When I hook the relay back and re-measure, I see 0.03-0.05V. I see this voltage till the ECM relay kicks off and then the voltage goes to 0V which I expect.
If anyone would be able to back probe their EKP relay pin 1 under a couple circumstance (engine off key in position 2 and engine running) it would be a huge help.

This confirms the DME failed to output 5v or higher during pump priming.