• Welcome Guest! If you are already a member of the BMW MOA, please log in to the forum in the upper right hand corner of this page. Check "Remember Me?" if you wish to stay logged in.

    We hope you enjoy the excellent technical knowledge, event information and discussions that the BMWMOA forum provides. Why not take the time to join the club, so you can enjoy posting on the forum, the club magazine, and all of the discounts and benefits the BMWMOA offers?

    Want to read the MOA monthly magazine for free? Take a 3-month test ride of the magazine; check here for details.

  • NOTE. Some content will be hidden from you. If you want to view all content, you must register for the forum if you are not a member, or if a member, you must be logged in.

fuel pump failure?

aapasquale

aapasquale
fuel pump failure? VICTORY!!!

Hi all-
Just got back from a trek to Bob's BMW in Maryland. Had SS braided brake cables and bar-backs installed on my 1994 R1100RS--drove back and forth from east end of Long Island (about 600 miles)--when within 1/4 mile of my home, bike just stopped and would not restart--battery good, fuses good--cranks well but doesn't turn over--when turning switch on, I don't hear that familiar whirring sound of fuel pump bringing fuel line up to pressure--I'm assuming this is a fuel pump problem--bike has 40,000 miles--any other suggestions before I call Beemer Boneyard and others for a replacement? Thanks in advance for your input.

Tony

PS--Bob's is very good--worth the trip--traffic in that area is unbelieveable!
 
Last edited:
Hi all-
Just got back from a trek to Bob's BMW in Maryland. Had SS braided brake cables and bar-backs installed on my 1994 R1100RS--drove back and forth from east end of Long Island (about 600 miles)--when within 1/4 mile of my home, bike just stopped and would not restart--battery good, fuses good--cranks well but doesn't turn over--when turning switch on, I don't hear that familiar whirring sound of fuel pump bringing fuel line up to pressure--I'm assuming this is a fuel pump problem--bike has 40,000 miles--any other suggestions before I call Beemer Boneyard and others for a replacement? Thanks in advance for your input.

Tony

PS--Bob's is very good--worth the trip--traffic in that area is unbelieveable!

First thing, check the fuse 6.

Second thing, swap the fuel pump relay with the load relief relay.

Next, make sure the connector on the right side, just below the fuel tank, is fully seated. Since that is what was taken apart to do the SS brake lines, that's the first place to look.

RB
 
If the fuses and fuel pump check out OK, I would look to the Hall Effect Sensor (HES). The HES itself doesn't usually go bad in bikes of this age but the wiring insulation can become embrittled and cause the failure. The bike will crank just fine but will not start.
 
Hi all-
Just got back from a trek to Bob's BMW in Maryland. Had SS braided brake cables and bar-backs installed on my 1994 R1100RS--drove back and forth from east end of Long Island (about 600 miles)--when within 1/4 mile of my home, bike just stopped and would not restart--battery good, fuses good--cranks well but doesn't turn over--when turning switch on, I don't hear that familiar whirring sound of fuel pump bringing fuel line up to pressure--I'm assuming this is a fuel pump problem--bike has 40,000 miles--any other suggestions before I call Beemer Boneyard and others for a replacement? Thanks in advance for your input.

Tony

PS--Bob's is very good--worth the trip--traffic in that area is unbelieveable!

LLOOOOVEEEE Bob's!!! Sister lives in Annapolis and I always build in time to stop!!
 
I'm not sure about your bike, but my 96 R1100RT, the load relief relay and the starter relay are different. On mine, the starter relay has a diode in it and it's BMW proprietary. I've cooked two in the last few years and now I have a spare for myself or my buddies. All the other relays can be swapped by part number from NAPA. You can do some detailed troubleshooting of the pump and hot wire as well. Pin 2 is power and Pin 1 is ground. You should have less than a tenth of an ohm to ground and between Pins 1 & 2, around 3 ohms is good. That number can be a bit higher to almost 10 ohms depending on temperature but 0 ohms be bad. :beer
 
If the fuses and fuel pump check out OK, I would look to the Hall Effect Sensor (HES). The HES itself doesn't usually go bad in bikes of this age but the wiring insulation can become embrittled and cause the failure. The bike will crank just fine but will not start.

How do you go about testing the fuel pump? Does it have to be removed from the tank or is there a test which can be done externally? How does one go about testing the Hall Effect Sensor?

I checked the #6 fuse on my bike this morning and it is fine. I pulled apart the connector under right side of fuel tank and it is perfectly clean. I will hook up a voltmeter and Ohmeter and see where things lie. Will check relays during the next couple of days as well and will report back. I love this stuff!
 
How do you go about testing the fuel pump? Does it have to be removed from the tank or is there a test which can be done externally? How does one go about testing the Hall Effect Sensor?

I checked the #6 fuse on my bike this morning and it is fine. I pulled apart the connector under right side of fuel tank and it is perfectly clean. I will hook up a voltmeter and Ohmeter and see where things lie. Will check relays during the next couple of days as well and will report back. I love this stuff!

Two things activate the fuel pump. Turn the key on - all other interlocks such as the sidestand, neutral switch, kill switch, etc) closed - the Motronic energizes the fuel pump for a few seconds without any signal from the Hall Effect Sensor. So if the normal key on routine is not starting the pump there is no reason to suspect the HES.

I don't know the pinouts on the connector on the tank, but applying 12v to the 12v pin and ground to the ground pin on the tank side of the connecting plug should make the pump run. You will need to find the schematic and have a couple of 2 foot jumper wires to the battery to perform this test.

Before I did anything else I would check the fuse, check the relay, unplug and inspect the tank connection and unplug and check the big plug at the Motronic. I would also check, and jumper if needed, the sidestand switch. My bet is it is either a loose connection or the sidestand switch.

PS: When I installed Motolights on an R1100RS I used a switched circuit that was killed with the sidestand switch as the trigger for the Motolights switch and relay coil. It has caused a couple of panics when the Motolights didn't come on because the sidestand was down, but it sure makes troubleshooting the sidestand switch easy if I remember.
 
How do you go about testing the fuel pump? Does it have to be removed from the tank or is there a test which can be done externally? How does one go about testing the Hall Effect Sensor?

I checked the #6 fuse on my bike this morning and it is fine. I pulled apart the connector under right side of fuel tank and it is perfectly clean. I will hook up a voltmeter and Ohmeter and see where things lie. Will check relays during the next couple of days as well and will report back. I love this stuff!

If your fuel pump isn't coming on at key on, I don't see how that would be caused by a failed HES. At that point the engine isn't turning.

Next, as you've said you plan to, swap the Load Relief and Fuel Pump relays. OR pull the fuel pump relay and jumper pin3 to pin5 in the socket. The fuel pump will run even with the key off.

The other day while doing some testing, I had the bike on the sidestand, and in first gear, turned on the key to power up the fuel pump for 2 seconds so I could check power at the injectors (also from the fuel pump relay) ... NOTHING.

On your R1100, in order for the Motronic MA 2.2 to energize the fuel pump relay, the Motronic Relay must work and be energized. That circuit requires that Fuse 5 is good. Also the Kill Switch and Sidestand Switch must be working (if your RID comes on with Key On then those two switches are okay. Therefore if swapping the Load Relief and Fuel Pump relay don't make a change, check Fuse 5 and swap the Load Relief with the Motronic Relay (consult your manual so you know which relays are which).
 
First thing, check the fuse 6.

Second thing, swap the fuel pump relay with the load relief relay.

Next, make sure the connector on the right side, just below the fuel tank, is fully seated. Since that is what was taken apart to do the SS brake lines, that's the first place to look.

RB

thanks Roger--
fuse #6 is good--switched load control and fuel pump relays..no go (I suppose that could mean both are good ....or bad!)--checked electrical connector to fuel pump/sender...clean as a whistle and solid--

--is there an external test to check fuel pump so I don't have to remove it?
--new fuel pumps are available from ReCycle for half the price of OEM and I don't mind opening up the bike to replace it, but I'd like to be sure that is the problem.

--are there checks to determine if Hall Effect Sensor is functioning? Also, have friends who have had this problem on RTP's and have had to replace computers--is there a check which would show this up?

When this problem is rectified, I'll be in touch concerning our previous discussion of surging issue--thanks again for the use of your booster plug

Tony
 
If your fuel pump isn't coming on at key on, I don't see how that would be caused by a failed HES. At that point the engine isn't turning.

Next, as you've said you plan to, swap the Load Relief and Fuel Pump relays. OR pull the fuel pump relay and jumper pin3 to pin5 in the socket. The fuel pump will run even with the key off.

The other day while doing some testing, I had the bike on the sidestand, and in first gear, turned on the key to power up the fuel pump for 2 seconds so I could check power at the injectors (also from the fuel pump relay) ... NOTHING.

On your R1100, in order for the Motronic MA 2.2 to energize the fuel pump relay, the Motronic Relay must work and be energized. That circuit requires that Fuse 5 is good. Also the Kill Switch and Sidestand Switch must be working (if your RID comes on with Key On then those two switches are okay. Therefore if swapping the Load Relief and Fuel Pump relay don't make a change, check Fuse 5 and swap the Load Relief with the Motronic Relay (consult your manual so you know which relays are which).

sorry I didn't see these comments before my previous post--will check this out tomorrow
thanks!
 
Tony,

The HES failure is actually failure of the wiring to the sensors, not of the sensors themselves, and are common in older Oilheads. HES wiring failure is more likely the cause of the bike's sudden death than a failure of the fuel pump. Here's info about the HES and its wiring:http://advwisdom.hogranch.com/Wisdom/oilhead_hall_sensors.pdf In short, the wiring's insulation can't stand up to the heat (the wiring's in a hot place) and eventually fails.

Certainly continue with the diagnostics suggested here. If the pump doesn't ever go on, it may indeed be faulty., But many of us who had HES difficulties on Oilheads (I did on my '96 R1100RSL at ~120K miles) also had fuel pumps that ran without difficulty.
 
As per Paul Glaves suggestion why don't you hot wire the pump itself to check it. They are quite reliable normally and usually the problem is somewhere else. I looked at Doug Raymonds schematic.

http://www.mac-pac.org/tech/electrical-diagrams/

If you put 12 VDC on Pin 2 and ground on Pin 1 the fuel pump should spin. If it doesn't the pump may be your problem or the wiring to it etc. but if it does the interlocks need to be confirmed and you need to trace the voltage back to the fuse/relay box.

Side stand switches are notorious offenders. Just sayin.
 
As per Paul Glaves suggestion why don't you hot wire the pump itself to check it. They are quite reliable normally and usually the problem is somewhere else. I looked at Doug Raymonds schematic.

http://www.mac-pac.org/tech/electrical-diagrams/

If you put 12 VDC on Pin 2 and ground on Pin 1 the fuel pump should spin. If it doesn't the pump may be your problem or the wiring to it etc. but if it does the interlocks need to be confirmed and you need to trace the voltage back to the fuse/relay box.

Side stand switches are notorious offenders. Just sayin.

hi Happy Wanderer--
that test will be done tomorrow morning--seems the most direct to find out whether the pump is the problem or not--then
i'll be troubleshooting from there--Today I take people on shark dives.....really
 
Have checked all fuses and switched appropriate relays around and cross-checked them. All seem to be functioning as they should. hot-wired the fuel pump through large connector under right side of tank. all I hear is a slight click from fuel tank, but nothing turns. Seems to me this would indicate some type of fuel pump failure and not a wiring problem.

question: on this bike, with the sidestand down, would the engine crank and just not start....or.......would nothing happen until sidestand is brought up? I will check this in the A.M. Do not have bike with me this evening.
My next step, after this question is answered, is to remove fuel tank from bike and have at it.

Tony
 
thanks! I certainly am looking forward to having my bike back!

Glad to hear you found the problem. And the clicking sound you hear means the wiring is not the problem! :p

When you get it out try hooking it up to a battery in reverse polarity. Read about that trick here and I think it was Paul Glaves who posted it. Sometimes something is stuck in the impeller and spinning the pump backwards frees it up.

I was not so lucky when mine failed. It sucked in some plastic shards from where I don't know but the filter sock was worn open and allowed the junk to get in there. Gas pumps deliver all sorts of debris to our tanks I guess.

Check out beemer boneyard or Euromotoelectric for inexpensive pump replacements.
 
Thanks for the tip about reversing polarity--will give it a shot--have already ordered a new aftermarket replacement from Re-Psycle in the mid-west--should arrive any day--
Tony
 
Back
Top