Fuel Issue on '99 R1100RT

[cburgdof]

This is a great forum, I've learned a lot the last month since buying a '99 R1100RT. I've put on 1500 miles in the last month, without any problems. Last night I filled up with premium, and had more trouble getting it started at the pump than ever before. Also had a couple skips/hesitations in the first couple miles after fill up. I put on about 100 miles and had a little bit of trouble starting when the engine was warm. When I went to start it this AM, it turned over but wouldn't fire. Figured it was some bad gas. Tried pulling plugs and using starting fluid and it would fire, but die as soon as the ether burned off. I tried dumping in some gas dryer, but that didn't work either. I drained and pulled the tank, checked the fuel filter, could easily blow through it so that seems okay. Then I realized that I hadn't heard the fuel pump whir. So I hooked up the fuel pump wiring harness (tank still off) turned the key on and didn't hear anything (I have checked the FP fuse earlier). So is this a bad fuel pump? Is there a way to test it? Was the problems starting after a fill up just coincidence? Sorry for the long first post, hope someone can steer me in the right direction.

 

[Mark K]

You can pull a fuel line at one of the injectors and turn the ignition on. Please aim it toward a container.

 

 

You should give this thread a read.

 

 

To isolate the problem further, you can apply 12v battery power DIRECTLY to the pump, bypassing the fuel pump circuit. (I hope you still have it opened up if you wish to do this).

 

 

[cburgdof]

I looked at the link you provided.

 

Checked fuse #6, 12v back side, 0v front side.

 

Where is terminal #30 & #87?

 

Direct wired batt to fuel pump and it pumped fine, so FP seems okay.

 

Remembered that I had soaped up the windshield pretty good when I put in gas. Could it be the HES?

[Michaelr11]

One easy check; swap the fuel pump relay with the horn relay. If the fuel pump relay is bad or has a bad terminal connection it will not allow the fuel pump to activate. Also, sounds like fuse 6 is blown; do you have a spare 15A fuse to slide into there?

[cburgdof]

Thanks, switched the horn & FP relays, Horn wouldn't work, but the FP worked. Is that it? Anything else I should check before starting to put it back together?

[cburgdof]

Okay, I sat the tank back on the bike, hooked up fuel lines and elec harness. Still won't fire, switch the relays and now neither one will work on horn. Pull the fuel lines and no pumping. What could have shorted out both relays?

[Michaelr11]

What about Fuse #6? You said it had zero volts on one side...

 

Fuse 6: Blue, 15A; Fuel Pump, Injectors, Timing valve, Lambda sensor, Relay #6 (fuel pump relay).

[cburgdof]

Fuse 6 is good I changed it and verified continuity. I'm stumped on what to do next.

[Galactic Greyhound]

Fuse 6 is good I changed it and verified continuity. I'm stumped on what to do next.

 

Here's how it works:

The battery feeds power (+12v) direct to Fuse#6 then to the Fuel Pump Relay contact. When the Fuel Pump relay is operated, the Fuel Pump Relay contact feeds the power to the Fuel Pump via pin #2 on the Fuel Plate connector (Green/white wire) and also to the Fuel Injectors.

 

When you first switch the Ignition 'On', the Fuel Pump Relay operates and the Fuel Pump runs for about 2 seconds. The ground for the Fuel Pump Relay coil is supplied via the Motronic Unit. After 2 seconds, the Motronic Unit removes the ground from the Fuel Pump Relay causing it to release and so cut the power to the Fuel Pump and the Injectors. The Fuel Pump Relay (and hence the Fuel Pump) will not operate again until the Motronic Unit gets a fuelling signal from the lower (180 degree) Hall Effect Sensor (HES) Ignition Trigger Unit when the engine is turning.

 

Note that the Fuel Pump Relay gets its coil power via the Ignition Switch (On), Kill Switch (Run) and Sidestand Switch (Stand Up)so any break in this safety interlock circuit will prevent the Fuel Pump Relay from operating.

 

What to do:

You need to check that the Fuel Pump Relay operates and supplies power to the Fuel Pump for 2 seconds when you first switch the Ignition 'On' - you can usually hear the pump running to confirm this. If you cannot hear the Fuel Pump then check for power at Plug pin #2 (Green/white wire) on the main loom side of the Fuel Plate Connector which is on the RH side of the bike just under the rear of the petrol tank.

 

If you get power for two seconds at Ignition 'On' and then it goes off that is OK. You now need to crank the engine and check that you get power restored on Plug pin #2 when the Motronic Unit gets the fuelling pulses from the HES and re-operates the Fuel Pump Relay.

 

Attached is a diagram of the Fuel Plate Wiring showing the connector to help things along.

 

Note that Plug pin #1 (Brown wire) is the frame ground to the Fuel Pump so check this ground is OK.

 

See how you get on with the above and report back.

[cburgdof]

I get .22v dc when the key is turned on for 2 sec, then the same (.22v dc) when ignition engaged. Just to verify my multimeter, I get 11.77v dc from my battery terminals.

[Galactic Greyhound]

I get .22v dc when the key is turned on for 2 sec, then the same (.22v dc) when ignition engaged. Just to verify my multimeter, I get 11.77v dc from my battery terminals.

 

Hi cburgdof,

 

Assumed that you are measuring on Fuel Plate Connector Plug pin #2 (Green/white wire) to ground and getting .22v DC within 2 seconds of switching the Ignition 'On'.

 

Assumed that when you say 'ignition engaged' you mean the Starter Button operated to crank over the engine?

 

Just in case your test ground is faulty, clip the multimeter ground lead to the battery 12v- terminal.

 

If the result is still the same, it is likely that this is caused by the Fuel Pump Relay not operating to provide power on the Fuel Plate Connector Plug pin #2.

 

You now need to measure voltages on the Fuel Pump Relay socket base. Keep the multimeter 12v- lead on the battery 12v- terminal.

 

Pull out the Fuel Pump Relay and look on it for the terminal numbers for the relay pins. You need to relate these terminal numbers to the sockets on the relay socket base. Leave the relay out.

 

First let's see if there is any power to operate the relay coil. With the Ignition 'On', the Kill Switch in the 'Run' position and the Sidestand in the 'Up' position, you should measure +12v on the Fuel Pump Relay socket base terminal 86.

 

Check this out and report back.

 

 

 

 

 

 

 

[cburgdof]

Hi Ced and thanks for your help.

 

Yes to your first 2 assumptions.

 

Clipped Meter ground to bat 12v-. Same result as in last post.

 

I could not find the terminal number 86. My relays have 1, 2, 5, 3 on the terminals. The terminal spades 3 & 5 are forward and perpendicular to the plane of the wheels. Terminal spades (left to right) 2 & 1 are behind and parallel to the wheels. Looking down into the fusebox from the back, (with the - & 1 indicating terminals,) the terminal layout is like this:

 

- #3

- #5

1 1

 

#2 #1

 

I hope that is clear, I could try to send a photo if that would help.

 

Meter still clipped to batt neg, with ignition on, K-switch on run, sidestand up, the front most terminal (#3) gives me 12V; #5 has 0v; leftmost terminal #2 has 0v; #1 has 12v.

 

 

My concern is that I had already seemed to determine that the relays themselves are shorted out. As I said in the post before you started trying to help me, I switched the horn &

fuel pump relay and then the pump started working and the horn did not. But after a cranking the engine a few times (with the horn relay in the FP slot) the fuel pump stopped working and then neither relay would work either the horn or the FP.

 

One thing that might have led to shorting out the switched relay is that by accident I did crank the ignition for about 30-60 seconds with no fuel in the tank (and pump). Could that have destroyed the relay?

 

I am sorry if my description is confusing. Let me know if I can clarify anything.

[Selden]

One thing that might have led to shorting out the switched relay is that by accident I did crank the ignition for about 30-60 seconds with no fuel in the tank (and pump). Could that have destroyed the relay?

Could that have destroyed the fuel pump?

[Galactic Greyhound]

Hi cburgdof,

 

Re the relay terminal numbers - you may have an aftermarket rather than an original relay fitted. I'll pull the relay on my bike and draw up a wiring diagram for the Fuel Pump circuit and relay terminals which will make testing a lot easier - will repost with the diagram in a couple of hours.

[Galactic Greyhound]

Hi cburgdof,

 

My Fuel Pump Relay has the same designations as yours. I agree with your socket base designation positions except for #1 and #2 which are reversed. See the attached R1100RT Fuel Pump Circuit diagram which I have attached. This diagram also shows the relay socket base designations. Have a look at the diagram and it will make things a lot clearer as to what is happening.

 

From your last tests, the rear right most terminal on the socket base looking forward (#2 not #1) showing +12v is correct - this means the safety interlock circuit is supplying power to one side of the relay coil (#2).

 

Keep the relay removed. The next test is to see if the Motronic Unit is supplying the ground (from EKR) to operate the Fuel Pump Relay for 2 seconds only when the Ignition is switched 'On'. To do this test, you will likely need to use a thin wire to pick up one of the base socket terminals unless your meter probes are very thin.

 

Set the meter to read 12v DC. Connect the positive lead to the socket base terminal #2 (rightmost) and the negative lead to socket base terminal #1 (leftmost). Make sure the leads are not shorting. Now you need to be quick and watch the meter here as the voltage is only on for 2 seconds and most digital voltmeters take a second or so to display a reading - switch on the Ignition - the meter should read 12v then fall to zero.

 

Check it out.

[cburgdof]

Hi Ced,

 

Just for a try, I went and bought a replacement relay. I put it in, reconnected all the fuel lines, made sure there was fresh gas and it fired right up. I haven't had a chance to really road test it, but did run it a couple miles without a problem.

 

I think what happened is that I did have bad gas but I blew both relays when I was checking the fuel pump--without fuel in the tank. Luckily, the relays did their job and my stupidity did not result in burning out the FP.

 

Thanks for all your help and advice. I now know a whole lot more about how the fuel system works than I did a couple days ago.

 

CB

[Galactic Greyhound]

Hi cburgdof,

 

Glad to hear you have got a result and hopefully the bike will continue running OK. The Fuel Pump Circuit diagram gives sufficient info to allow you to test your suspect relays on the bench using a spare battery and a testmeter. I'm not sure how you would manage to blow a relay - it may be that just one was originally faulty and that caused a glitch with the testing.

 

The relays for the Fuel Pump, Load Relief, Horn and Motronic are all the same BMW Part Number 61361393412 and are interchangeable.

[cburgdof]

Thanks Ced,

 

I've run it about 300 miles without any further problems.

 

BTW, I ended up finding the generic version of the relay. It was $7, whereas the BMW price is $17.

 

It is made by Borg Warner PN # R3154.

 

Here in the states, Auto Zone has it as PN # 19997 or 41-5154.

Advance Auto is PN # 19970030 and NAPA is PN # AR614.

 

I now have a spare that rides in my on-board tool kit.

 

-CB