Fuel Pump has no power

dallasf · 1 Fuel Pump has no power - lost Sun Nov 22, 2020 4:11 pm

dallasf

Silver member

Number of posts : 129

Hi,

So I am very new to the world of the BMW K's and motorbikes in general (technically). Have always ridden and enjoyed bikes but never really pushed myself to learn what is "underneath".

I searched for quite a long time to find the right bike and came across a beaten up k100 RS SE 1989. It had been stored in a garage for about 4 years and looked like it has potentially been dropped, with only minor damage. The bike is a non-starter and that's kind of what I wanted to really learn.

Please excuse the below information it may seem incorrect as it may well be. I tried to follow the guides and forum posts best I could. The overall issue I have is that the fuel pump is not getting any power. I have checked the following:

New Battery

Bike is on the center stand - side stand is up

Bike is in neutral

Bike cranks no problem with ignition on, no key as key lock was jammed. I juts use a screw driver to turn it on.

Cleaned grounding points – were filthy

Removed fuel pump and connected 12v and had a steady stream of fuel. This did not occur whilst in the tank.

Replaced fuel filter

Water temp light is NOT on

12v multimeter test connection at the fuel plug which connects to the tank on all 4 pins when starter active, I hear this can be the cause – reads:

White 7.9
Yellow 7.4
Brown .23
Green 10.26

Tested wires from fuel pump connection to external pin connection, no issues, no wires broken.

All fuses are tested and working

Fuel Pump relay tested, can hear it open and shut with 12v, check via multimeter and appears to be working fine.

FI Relay - Put the red lead of my tester on pin 30 of the socket and the black one to a good ground - all clear

FI Relay - Put the red lead of your tester on pin # 86 and the black one to a good ground. When I turn the ignition key ON I was reading 12v on the meter.

FI Relay - Put the red lead of the tester to the positive (+) of the battery and the black lead to pin # 85 of the socket. When I press the starter button read 12v on voltmeter. IT READS ABOUT +10.9

Next step is to check the power from the relay to fuse #6 (I apply 12v to test the pump. To do so, I reconnect the relay. Got a good ground on the black lead voltmeter and when pressing the starter button, touch each side of the fuse with the red lead. Worked with 12v

Power from ECU connector to FI relay 85 registers nothing but 86 reads 12v - might be the cause?

I placed the multimeter (12v) on pin 12 of the EFI connector and then to the injector, which returned no results, thoughts??

Remove the FI relay again and got the voltage at pin #30 of the socket - All fine, correct voltage.

Got an LED and attached the LED to the injector and started the bike, this starting flashing at me. I hear if the injectors don't start the pump won't.

Guys I am lost, I have read the flow diagram but I am really scratching my head as I do not really under the instructions all that well.

I do apologise if the above seems not "technically" correct.

Your help is much appreciated.

Thanks, Dallas

Last edited by dallasf on Sun Nov 22, 2020 10:28 pm; edited 3 times in total

robmack · 2 Re: Fuel Pump has no power - lost Sun Nov 22, 2020 5:38 pm

robmack

Life time member

Number of posts : 2334

Have you looked at the tank connector itself. The contacts are prone to deforming which can interrupt the connection. I would use a small jeweller's screwdriver to slightly close the female contacts and try again. The important ones are the Green / White and Brown.

dallasf · 3 Re: Fuel Pump has no power - lost Sun Nov 22, 2020 5:44 pm

dallasf

Silver member

Number of posts : 129

robmack wrote:Have you looked at the tank connector itself. The contacts are prone to deforming which can interrupt the connection. I would use a small jeweller's screwdriver to slightly close the female contacts and try again. The important ones are the Green / White and Brown.

Yep, had a good look at those, cleaned them and tested the connection. I hadn't tried closing them to get a better connection, will try this week.

dallasf · 4 Re: Fuel Pump has no power - lost Sun Nov 22, 2020 11:29 pm

dallasf

Silver member

Number of posts : 129

If my ignition turns on the dashboard lights and can power the starter, I can assume that the ignition is not faulty?

robmack · 5 Re: Fuel Pump has no power - lost Sun Nov 22, 2020 11:58 pm

robmack

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Number of posts : 2334

No, you cannot make that assumption. The ignition sequence is involved. The indicator lights powering up and the started turning over are only parts of the sequence and other events have to happen at the right time for the engine to start. Read about the sequence at this page:

https://www.kforum-tech.com/electrical/EFI/bike-wont-start-EN.htm

A description of the start sequence is about halfway down the page.

dallasf · 6 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 5:48 am

dallasf

Silver member

Number of posts : 129

Thanks for helping me out, I really appreciate it.
I am following the process flow diagram in that link, the first item to test is "power from ignition switch to pin 86". I am assuming I am removing the relay, grounding my multimeter and attaching the other to pin 86 and running the starter. This will tell me if the ignition and power to relay is good?

I also read the insert half way down, I believe that both relays are working fine. As for the hall sensor I would have to check.

Thanks again

92KK 84WW Olaf · 7 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 6:03 am

92KK 84WW Olaf

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Number of posts : 7967

You mention no temperature light comes on.

Sort that first and make sure the fault is just the bulb itself and nothing more as there is an inhibit function, if the bike thinks it has overheated.....no start. Most likely to be connections but there is one on the sensor its and its buried behind the radiator.

dallasf · 8 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 6:16 am

dallasf

Silver member

Number of posts : 129

92KK 84WW Olaf wrote:You mention no temperature light comes on.

Sort that first and make sure the fault is just the bulb itself and nothing more as there is an inhibit function, if the bike thinks it has overheated.....no start. Most likely to be connections but there is one on the sensor its and its buried behind the radiator.

Hi, thanks for helping. Is it possible the temperature sensor is right, since the bike hasnt started in months.

Or should I check the sensor no matter as it might be tricking the bike to not start?

92KK 84WW Olaf · 9 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 6:41 am

92KK 84WW Olaf

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Number of posts : 7967

You are more likely to be suffering from an electrical connection issue than a faulty component, so all of the fuses, earths, electrical connections, plugs, pins need to be checked AND cleaned up and that's really just time/patience/methodical approach and no damage to your pocket.

Some issues cause over fuelling but others cause non start.

dallasf · 10 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 6:50 am

dallasf

Silver member

Number of posts : 129

92KK 84WW Olaf wrote:You are more likely to be suffering from an electrical connection issue than a faulty component, so all of the fuses, earths, electrical connections, plugs, pins need to be checked AND cleaned up and that's really just time/patience/methodical approach and no damage to your pocket.

Some issues cause over fuelling but others cause non start.

Ok great, I'll try this as well. Recommendations for cleaning electrical components?

robmack · 11 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 8:05 am

robmack

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Number of posts : 2334

dallasf wrote: Recommendations for cleaning electrical components?

Use an electrical contact cleaner; Deoxit is highly recommended because it cleans and applies a protective coating all at the same time. Spray the cleaner onto the contacts and do several engage/disconnect cycles with the plug so that the pins wipe across the sockets and burnish the metal. This action will remove corrosion and improve electrical contact.

Holister · 12 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 8:40 am

Holister

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Number of posts : 2491

dallasf wrote:

92KK 84WW Olaf wrote:You mention no temperature light comes on.

Sort that first and make sure the fault is just the bulb itself and nothing more as there is an inhibit function, if the bike thinks it has overheated.....no start. Most likely to be connections but there is one on the sensor its and its buried behind the radiator.

Hi, thanks for helping. Is it possible the temperature sensor is right, since the bike hasnt started in months.

Or should I check the sensor no matter as it might be tricking the bike to not start?

The sensor is worth checking out before you go any further imo. It's an easy check. Just measure the impedance between pins #10 and #13 on the FICU plug. If the sensor is reading a closed short ie very low ohms then it's signaling overheated and the start sequence won't initiate. At operating temperature it should be read around 300Ω. At 20ºc you'll get a reading of 2.5kΩ
Good luck Very Happy

robmack · 13 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 8:57 am

robmack

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Number of posts : 2334

Out of curiosity, if you were to separate the tank connector from the harness and measure the resistance between Green/White and Brown on the tank lead, what resistance would it show? I'm expecting in the tens to hundreds of Ohms.

dallasf · 14 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 4:54 pm

dallasf

Silver member

Number of posts : 129

I am assuming that's to ensure there are no breaks to the brown and black leads which connect to the pump?

dallasf · 15 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 4:55 pm

dallasf

Silver member

Number of posts : 129

Holister wrote:

dallasf wrote:

92KK 84WW Olaf wrote:You mention no temperature light comes on.

Sort that first and make sure the fault is just the bulb itself and nothing more as there is an inhibit function, if the bike thinks it has overheated.....no start. Most likely to be connections but there is one on the sensor its and its buried behind the radiator.

Hi, thanks for helping. Is it possible the temperature sensor is right, since the bike hasnt started in months.

Or should I check the sensor no matter as it might be tricking the bike to not start?

The sensor is worth checking out before you go any further imo. It's an easy check. Just measure the impedance between pins #10 and #13 on the FICU plug. If the sensor is reading a closed short ie very low ohms then it's signaling overheated and the start sequence won't initiate. At operating temperature it should be read around 300Ω. At 20ºc you'll get a reading of 2.5kΩ
Good luck

not home for a few days but will check this out. Thanks!!

robmack · 16 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 6:13 pm

robmack

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Number of posts : 2334

dallasf wrote:I am assuming that's to ensure there are no breaks to the brown and black leads which connect to the pump?

Correct. It could point to connector problems or wire breaks.

92KK 84WW Olaf · 17 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 6:24 pm

92KK 84WW Olaf

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Number of posts : 7967

Fuel Pump relay tested, can hear it open and shut with 12v, check via multimeter and appears to be working fine.

Happy there is 12v coming into the relay pins in the relay box?

dallasf · 18 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 7:10 pm

dallasf

Silver member

Number of posts : 129

hi, not overally happy as per the following tests:

So my testing here was:

FI Relay - Put the red lead of my tester on pin 30 of the socket and the black one to a good ground - all clear

FI Relay - Put the red lead of multimeter on pin # 86 and the black one to a good ground. When I turn the ignition key ON I was reading 12v on the meter.

FI Relay - Put the red lead of the tester to the positive (+) of the battery and the black lead to pin # 85 of the socket. When I press the starter button read 12v on voltmeter. IT READS ABOUT +10.9

Power from ECU connector to FI relay 85 registers nothing but 86 reads 12v - might be the cause? I read that there should be power to #85?

mritz · 19 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 8:15 pm

mritz

active member

Number of posts : 23

Just my 50c here...
I've been trying everything...isolate and tested cables, relays, pump...etc.
After a lot of frustration, I figured that my connector was entering in the wrong position.
All times! Unbelievable. There a grove and a guide...in my case, I was able to connect wrongly 50 times in a roll...

After days fighting...I decided to take another look and PAW... I was connecting 90 degrees wrongly...problem solved, 0$ spent.

92KK 84WW Olaf · 20 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 10:04 pm

92KK 84WW Olaf

Life time member

Number of posts : 7967

mritz wrote:Just my 50c here...
I've been trying everything...isolate and tested cables, relays, pump...etc.
After a lot of frustration, I figured that my connector was entering in the wrong position.
All times! Unbelievable. There a grove and a guide...in my case, I was able to connect wrongly 50 times in a roll...

After days fighting...I decided to take another look and PAW... I was connecting 90 degrees wrongly...problem solved, 0$ spent.

I doubt you are the first person to have done that...as said, being methodical and it doesn't hurt the pocket so you can shell out for a good beer on a clear conscience.

robmack · 21 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 10:07 pm

robmack

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Number of posts : 2334

dallasf wrote:hi, not overally happy as per the following tests:

So my testing here was:

FI Relay - Put the red lead of my tester on pin 30 of the socket and the black one to a good ground - all clear

FI Relay - Put the red lead of multimeter on pin # 86 and the black one to a good ground. When I turn the ignition key ON I was reading 12v on the meter.

FI Relay - Put the red lead of the tester to the positive (+) of the battery and the black lead to pin # 85 of the socket. When I press the starter button read 12v on voltmeter. IT READS ABOUT +10.9

Power from ECU connector to FI relay 85 registers nothing but 86 reads 12v - might be the cause? I read that there should be power to #85?

Your tests are showing normal operation. Why are you disappointed?
I would expect to see:
- almost full battery voltage on Pin 86 (green/yellow) relative to ground with ignition turned on, 0 volts otherwise.
- about 10-11 volts from pin 85 (yellow/brown) relative to ground. Lower reading accounts for voltage drop across the relay coil
- almost full battery voltage on pin 30 (red) relative to ground
- almost zero volts on FI pin 7 relative to ground when activated

make sure you are getting about full battery voltage on both pins 87 (green/red) relative to ground when the FI relay is activated.

dallasf · 22 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 11:01 pm

dallasf

Silver member

Number of posts : 129

I guess I am disappointed (more like scratching my head) because it all seems ok, but still no power to pump.

Based on your last actions, I will try the following: Just a few questions in red.

- almost full battery voltage on Pin 86 (green/yellow) relative to ground with ignition turned on, 0 volts otherwise.
- about 10-11 volts from pin 85 (yellow/brown) relative to ground. Lower reading accounts for voltage drop across the relay coil
- almost full battery voltage on pin 30 (red) relative to ground
- almost zero volts on FI pin 7 relative to ground when activated - Not sure how, where is pin 7 sorry?

robmack · 23 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 11:07 pm

robmack

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Number of posts : 2334

My mistake. That statement is wrong and should ignore it.

Laitch · 24 Re: Fuel Pump has no power - lost Tue Nov 24, 2020 2:01 am

Laitch

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Number of posts : 3262

dallasf wrote:The bike is a non-starter and that's kind of what I wanted to really learn.

Some times wishes are granted! cheers

dallasf · 25 Re: Fuel Pump has no power - lost Tue Nov 24, 2020 2:10 am

dallasf

Silver member

Number of posts : 129

Laitch wrote:

dallasf wrote:The bike is a non-starter and that's kind of what I wanted to really learn.

Some times wishes are granted!

Definitely learning! Not frustrated quite yet.

daveyson · 26 No go Tue Nov 24, 2020 6:57 pm

daveyson

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Number of posts : 1339

So the pump works when connected to a battery. Does it work when connected to a battery, including a fuse, through the unplugged tank connector?

If so, you have power to the plug, and power from the plug, so it's the plug. Sometimes a mediocre plug can test good, but fail under load.

dallasf · 27 Re: Fuel Pump has no power - lost Tue Nov 24, 2020 7:06 pm

dallasf

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Number of posts : 129

daveyson wrote:So the pump works when connected to a battery. Does it work when connected to a battery, including a fuse, through the unplugged tank connector?

If so, you have power to the plug, and power from the plug, so it's the plug. Sometimes a mediocre plug can test good, but fail under load.

great point, will try that. At work for a few days, so looking forward to getting home and trying all these options out.

daveyson · 28 No go Tue Nov 24, 2020 7:11 pm

daveyson

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Number of posts : 1339

I spose I should have said "power and earth" where I said "power"

dallasf · 29 Re: Fuel Pump has no power - lost Thu Nov 26, 2020 10:47 pm

dallasf

Silver member

Number of posts : 129

Ok, so I have an update and some questions.

I cleaned all the ground connections with Dexoit.

As per suggestions for testing please see the following:

- almost full battery voltage on Pin 86 (green/yellow) relative to ground with ignition turned on, 0 volts otherwise. 10.48 to 11.99
- about 10-11 volts from pin 85 (yellow/brown) relative to ground. Lower reading accounts for voltage drop across the relay coil - 10.4
- almost full battery voltage on pin 30 (red) relative to ground - I do not have a red cable on the connector from the bike to the tank. I have brown, white, yellow, green/white. However, all leads from that connector on the bike to tank returned true values.

make sure you are getting about full battery voltage on both pins 87 (green/red) (green/white) relative to ground when the FI relay is activated. 10.48

So, is there 12v on the green wire at the tank connector or not? Yes, power when I start the bike, when connector on ground to green/white wire connector on the bike (which connects to tank).

continuity between the GREEN wire on the outside to the YELLOW wire on the inside, I have a White, Yellow, Brown and Green connector from the tank to brown and black pump wires. If I do a Ohms test from green to brown I get 0018 to 0000. Not sure if I have performed this test correctly?? I get nothing if connecting green to black. If i do brown to black I get 0018 to 0000.

The sensor is worth checking out before you go any further imo. It's an easy check. Just measure the impedance between pins #10 and #13 on the FICU plug. If the sensor is reading a closed short ie very low ohms then it's signaling overheated and the start sequence won't initiate. At operating temperature it should be read around 300Ω. At 20ºc you'll get a reading of 2.5kΩ - I switched it to 2000ohms and got 1500 then it drops off like there is little connection.

Really sorry if this is vague or language is incorrect.

Trying my best to understand as a noob.

Thanks all.

dallasf · 30 Re: Fuel Pump has no power - lost Sat Nov 28, 2020 3:49 am

dallasf

Silver member

Number of posts : 129

This is resolved. Not sure what eventually solved it but cleaned everything and applied deoxit everywhere. Not kicking over yet, but have to do spark plugs and injectors. Thanks for everyone's help.

Suzi Q · 31 Re: Fuel Pump has no power - lost Sat Nov 28, 2020 3:54 am

Suzi Q

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Number of posts : 1378

Deoxit pretty much has the status of an honorary forum member Fuel Pump has no power - lost 112350

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2 Re: Fuel Pump has no power - lost Sun Nov 22, 2020 5:38 pm

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3 Re: Fuel Pump has no power - lost Sun Nov 22, 2020 5:44 pm

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4 Re: Fuel Pump has no power - lost Sun Nov 22, 2020 11:29 pm

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5 Re: Fuel Pump has no power - lost Sun Nov 22, 2020 11:58 pm

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6 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 5:48 am

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7 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 6:03 am

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8 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 6:16 am

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9 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 6:41 am

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21 Re: Fuel Pump has no power - lost Mon Nov 23, 2020 10:07 pm

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24 Re: Fuel Pump has no power - lost Tue Nov 24, 2020 2:01 am

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