bluesguitarboy Posted February 18, 2011 Share Posted February 18, 2011 Ok so it's 64 degrees in february in Ohio and I'm dreaming of putting at least 150 miles on the bike today. I start the bike put it in gear let out the clutch and it dies. I go to restart it and it just cranks. so I figure it's either a spark or a fuel problem. I take off the spark plug wires insert a tester in each side. Ground the tester and crank. A bright beautiful spark on each side. That leaves fuel. I open the air box douse it with starting fluid, turn on the ignition. Crack open the throttle to let the engine breath. It starts for 4 seconds and dies. So it is fuel. My guess is fuel pump. The bike has only 38000 miles. Is this common. What else might kill the fuel. If the hall effect sensor is bad will the computer cut fuel. Whats the best way to test the fuel pump? Any help will be appreciated. Link to comment
dirtrider Posted February 18, 2011 Share Posted February 18, 2011 Evening Anson First thing put your ear to the fuel tank then turn the key on—Can you hear the pump run for about 3 seconds? If so your problem is probably not the pump (maybe fuel injectors or power to the injectors, or other electrical) If you can’t hear the pump run than probably a pump problem or power TO the pump problem. Do a little more testing then get back to us with a little more specific info and we can guide you from there. Link to comment
bluesguitarboy Posted February 18, 2011 Author Share Posted February 18, 2011 Okay I found an excellent wiring schematic on the bmwmoa forum. I turned on the ignition and checked pins one and two. These are the wires which provide the fuel pump with 12v battery power when the ignition is on. I got 12 volts of power at the connector. I also listened for the fuel pump to cycle when you turn on the ignition all I heard was the brake servos activating (I hate the servo assisted linked brakes but thats another posting). So I'm leaning to fuel pump. Next I'll take the fuel pump out and bench test it. Link to comment
OlGeezer Posted February 18, 2011 Share Posted February 18, 2011 Okay I found an excellent wiring schematic on the bmwmoa forum. I turned on the ignition and checked pins one and two. These are the wires which provide the fuel pump with 12v battery power when the ignition is on. I got 12 volts of power at the connector. I also listened for the fuel pump to cycle when you turn on the ignition all I heard was the brake servos activating (I hate the servo assisted linked brakes but thats another posting). So I'm leaning to fuel pump. Next I'll take the fuel pump out and bench test it. Maybe before you go to all that trouble, you might check the fuel pump relay. I recently blew one. Link to comment
dan cata Posted February 18, 2011 Share Posted February 18, 2011 +1, and check the fuse also Dan. Link to comment
dirtrider Posted February 18, 2011 Share Posted February 18, 2011 Morning Anson If the terminals you checked are the (1) & (2) ( shown in your wire print) those are in the fuel pump connector feeding TO the tank itself so no need to bother checking the fuse or the relay. That area is post fuse and post relay so if you have power there the fuse and relay are working. If your pump doesn’t pass the bench test maybe try using a dental pick or small wire to see if you can reach in and spin the pump impeller (sometimes they corrode up due to moisture or moisture/alcohol in the fuel during storage. In any case if you bench run that pump only do it for a nano second as those pumps are internally cooled by fuel passing through them so it is easy to damage a pump by running it at high RPM with no fuel running through it. Link to comment
bluesguitarboy Posted February 19, 2011 Author Share Posted February 19, 2011 Okay benched tested the fuel pump for just a nano second (thanks D.R.) and it is not the problem. The problem is in the wiring to the fuel pump relay. I tested the relay it works fine. The wire which runs between the kill switch and the relay has a short. Using the diagram I determined that with the ignition and the kill switch in the on position if I pull the relay and ground the connection between the relay coil and the kill switch I should be getting 12v of power. This should close the relay and send power to the fuel pump. I am getting no power to the relay coil. I am getting 12v to the fuel pump fuse (fuse 6 (10A). I am not getting 12v when I ground the coil connection at the relay. I have no idea why. Tomorrow I will pull the fuse box and check the wiring harness to see whats going on. I swear I just want to ride. Link to comment
bluesguitarboy Posted February 19, 2011 Author Share Posted February 19, 2011 Also I almost forgot. There should be continuity between the coils of the mototronic relay and the fuel pump relay. I have none. gotta be a short or a loose wire. I'm tired will try again on Monday. Link to comment
dirtrider Posted February 19, 2011 Share Posted February 19, 2011 Afternoon Anson Not sure I understand what you are doing, you talk of a short but think you may instead mean an open (a short means shorted to something like ground or another circuit). Then you talk of removing the relay the grounding something (not sure what you mean here). In any case both the fuel pump relay and the Motronic relay (pull-in coil side) get POWERED from the ign switch (and through kill switch). The Motronic grounds the other side of the pull in coil to energies the relay. Keep in mind the Motronic will only ground the fuel pump relay pull in coil for about 3 seconds at initial key on then it drops the ground until the engine is cranked (or the engine is running). Just sitting there (key on) after 3 seconds the circuit goes open (Motronic drops it’s pull-in coil ground on the fuel pump relay) . Link to comment
bluesguitarboy Posted February 20, 2011 Author Share Posted February 20, 2011 D.R. Thanks for the info about Mototronic relay only grounding for 3 seconds explains alot. What I was trying to say is that if I pull the fuel pump relay and ground the pull in coil pin that leads to the ignition switch through the kill switch my Digital volt meter should read 12v as long as the ignition switch is on and the kill switch is closed. If I understand correctly this power from the battery closes the fuel pump relay and sends power to the fuel pump. My problem is that with the ignition turned on and the kill switch closed the fuel pump relay is not getting power to the pull in coil. The circuit remains open. Do you have any idea what would cause this. It happened suddenly. One second the bike is running the next it is not. Link to comment
Alan D Posted February 20, 2011 Share Posted February 20, 2011 Side stand switch. That's what I was thinking, or clutch switch. I had to wire around the clutch switch on my R1100RT Link to comment
dirtrider Posted February 20, 2011 Share Posted February 20, 2011 Morning Anson I’m still a little vague on what you are doing. Might be you are doing things correctly just explaining what you did in a non automotive way. 1)—“ What I was trying to say is that if I pull the fuel pump relay and ground the pull in coil pin that leads to the ignition switch through the kill switch my Digital volt meter should read 12v as long as the ignition switch is on and the kill switch is closed” You can’t/shouldn’t ever try to ground that side of the relay circuit as it powered by 12 volts so that would be shorting that 12 volt power (directly) to ground therefore overloading the circuit. Maybe you (mean) you are measuring the circuit at that point “to ground “- but actually grounding it should never be done. (2)- If I understand correctly this power from the battery closes the fuel pump relay and sends power to the fuel pump” The “battery” power to the relay doesn’t close the relay, that is the pump power supply side (powers the pump). The F/P relay is operated on the pull-in coil side with power to it from the ign switch through the kill switch. The relay is actually operated (turned on ) when the Motronic grounds the other side of the pull-in coil to complete the circuit and power the relay’s pull in coil. This grounding only happens for about 3 seconds at initial key on. Then again as the starter is cranked or the engine is running. (3)- “The circuit remains open. Do you have any idea what would cause this. It happened suddenly. One second the bike is running the next it is not” Well if I understand what you have been doing correctly you are saying with the key on and kill switch turned on you have no power to the fuel pump relay pull in coil (correct?) Do you have power to the pull-in coil on the Motronic relay? If so your problem probably lies in the green/?? wire Splice of the fuel pump green/// wire to the green/?? Wire going to the Motronic relay, OR a break in the green/?? wire going to the fuel pump relay OR a problem in the terminal connection at the relay OR an open at the side stand switch. So let me ask you this— *Do you have BATTERY power going to the fuel pump relay yes/no * Do you have power to the pull-in coil on the Motronic relay, key on kill switch on yes/no *if you hook a test light to the battery (+) post then test the Motronic controlled terminal on the fuel pump relay at first key on does the light light up for about 3 seconds yes/no *With the fuel pump relay in place do you have power to the fuel injectors with the engine cranking yes/no Link to comment
dirtrider Posted February 20, 2011 Share Posted February 20, 2011 Side stand switch. That's what I was thinking, or clutch switch. I had to wire around the clutch switch on my R1100RT Morning Alan Clutch switch only effects engine cranking not the fuel pump circuit. Even with a faulty clutch switch the fuel pump should still operate just the engine won’t crank unless the trans is in neutral. Link to comment
bluesguitarboy Posted February 20, 2011 Author Share Posted February 20, 2011 D.R. You are right. I said grounding what I meant was I placed a multimeter between the 12v pin on the fuel pump relay coil side and the negative battery terminal to measure the voltage and got a zero reading. You are also correct on number 2 Im not getting any voltage in the ignition switch, kill switch, fuel pump relay circuit but I think you are on to something. I would turn on the key and then try and measure the voltage. If I'm understanding you correctly that circuit would only be powered for 3 seconds. Tomorrow when I get home from work I will use a test light on that circuit the way you suggested. A couple of questions what does the mototronic relay do? Second question: The ignition sw,kill switch, mototronic relay circuit should this have 12v constantly when the switches are closed or is this only powered for a few seconds. Your help is much appreciated. Link to comment
bluesguitarboy Posted February 20, 2011 Author Share Posted February 20, 2011 D.R. Almost forgot. 1. Yes I have battery power to the fuel pump relay supply side. 2. I am at work now and will measure voltage to mototronic relay tommorrow. 3. Ill do the test light tommorrow 4. How do I measure power to the fuel injectors? Link to comment
dirtrider Posted February 20, 2011 Share Posted February 20, 2011 --- You are also correct on number 2 Im not getting any voltage in the ignition switch, kill switch, fuel pump relay circuit but I think you are on to something. I would turn on the key and then try and measure the voltage. If I'm understanding you correctly that circuit would only be powered for 3 seconds. Afternoon Anson Actually the PULL-IN COIL on the fuel pump relay is supposed to be powered up any time the key is on and the kill switch is on, The Motronic controls the relay by applying ground to the low (ground) side of the relay pull-in coil as needed. The low (ground) side controlled by the Motronic is what operates for 3 seconds at key up or full time engine running. If you aren’t getting any power to the relay’s pull in coil with the key on you have a broken wire or bad connection at a solder joint or at the terminal itself. Added: if your Motronic relay pull-in coil is also without power suspect a bad kill switch or broken wire in that area. You might also wiggle the main wire harness near the steering neck area (near the first tie strap retention area). That is a known area for broken wires. Link to comment
bluesguitarboy Posted February 21, 2011 Author Share Posted February 21, 2011 Okay I'm an idiot. I mixed up the sides of the pull in coil on the fuel pump relay. I was testing the side of the pull in coil that leads to the mototronic control unit for 12v when the key is on not the side that leads to the kill switch. What mislead me is when you test the kill switch side of the F.P.relay pull in coil for continuity with ground with the key off there is continuity. So I assumed this was the ground side. D.R. you steered me in the right direction when you stated the relay is only grounded for a few seconds when the ignition is first turned to the on position. I performed all of the tests you mentioned and they all worked. I replaced all of the relays and checked the connector that leads to the fuel pump for power when the ignition is first turned on. Sure enough the meter registered 12.5 volts at this connector for about 1.5 seconds. It then went to zero. I then hooked the multimeter to the fuel pump connector and cranked the engine sure enough 12.5 while the engine starter was pushed. So now I'm back to square one. I guess I'll check if there is power to the injectors. I am kinda stuck right now. I pulled the fuel pump and realised that the filter had never been changed. Now I am waiting for a filter kit from beemerboneyard. No sense in putting it back together when this has to be done. Any comments on if I should do the external filter mod? Link to comment
bluesguitarboy Posted February 24, 2011 Author Share Posted February 24, 2011 Found the problem. The plastic quick disconnect for the fuel tank supply side was broken. The bike tested out perfectly once I understood what I was checking for (Thanks D.R.) I went to put the tank back on and the Quick connect fell apart in my hand. Now to order the chrome ones from beemerboneyard. Link to comment
AndyS Posted February 24, 2011 Share Posted February 24, 2011 Nice to see you have it sorted now. Andy Link to comment
NonComp Posted February 24, 2011 Share Posted February 24, 2011 Gotta love those OEM quick disconnects. Real time savers (he said with tongue firmly in cheek). Link to comment
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