Sudden death

[TIV]

Hi folks. Spring is unusually late on the south/west cost off Iceland where I live, and we are enjoying the first day's out on our bikes. Today me and my wife decided to visit my mother, she lives in a small town about 50 miles from Reykjavik. My wife was riding her Yamaha FJ1200 and I was riding my beloved K75RT.

When we had only a mile or so left to my mothers house and I had just finished, with a certain air of superiority, overtaking a couple of Harley´s with "ape hangers", my bike died without a warning! I just about managed to save my face, by pretending I was stretching and enjoying the scenery, while the Harley pair rolled by. :2thumbup: Fortunately my mother has a garage and I left my baby there and got a ride home on my wife´s back seat.  :yow

It is obvious that the fuel pressure is gone. The fuel pump is dead. The fuse is OK. I´m pretty sure that it´s a electric failure of some sort. The thing is that this winter I renewed all rubber hoses internal and external, put in refurbished injectors, a new fuel pressure regulator and fuel filter. I also renewed the rubber and plastic rings on the pump, and the mesh filter at the bottom of it. I did not renew the electric loom that feeds the pump 12 Volts (presumably) inside the tank, it looked OK. I also cleaned out the tank. I have only driven it for about 100 miles since I did this and it has never run better. Until now..........  :eek:

This bike is 22 years old, but it has only about 20.000 miles on the clock from new. I would think that the pump should last longer than that? We have a relatively clean gasoline here I think.

Any suggestions where to start and how to go about it? I can´t get any spare parts here, so I´ll have to order everything from the UK or Germany. I hope it´s not the pump itself, it´s very expensive. Shipping, import taxes and VAT on top of everything can up to double the price I pay the seller. All suggestions appreciated.  :clap:

[Grim]

Is it priming when you turn the kill switch on?

Does the temp light come on when you turn on the kill switch?

The temp light along with the injectors are all powered when the kill switch is turned on. If the light doesn't come on you defiantly have a problem with the switch or the relay it activates.


Reseat the ECM plug and see what happens.

There is a thread k75 hesitation. Some good links were posted in that thread that has diagnostics.

[Grim]

Link I think will help

http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/bike-wont-start1.htm

[Inge K.]

Grim, K 75 have Jetronic, not Motronic.....and quite different symptoms.
I would have started with checking the four pole tank connector (common problem source).

[JamesInCA]

When the bike died, did the lights on the dash come on (brake, charge, oil pressure)?

If so, that would indicates what you had was a total electrical failure, rather than just a failure of the fuel pump; either is quite possible.

Try turning on the ignition and kill switch, and press the start button. Even while it's cranking, and for just a fraction of a second after, you should hear the pump buzz or whine. If it does, the pump is probably fine.

Also, change the fuel filter. Perhaps you had some old gas or maybe some water accumulated in the fuel pump well.

Has the rubber vibration damper around the pump ever been replaced? These decay and clog fuel filters regularly.

I'd say the first things to do are to determine if the fuel pump is even powering on (by listening), replace the fuel filter, and drain the tank/refill with known fresh gas.

[vesku]

I'm with Inge K. on this one. The tank connector might be loose.

[Grim]

Grim, K 75 have Jetronic, not Motronic.....and quite different symptoms.
I would have started with checking the four pole tank connector (common problem source).

The link I posted is for jetronic on a k100 and it is going to be fine for a k75. The only major diff is the coil set up and that is covered in the link. It has great diagrams and very well written. 

[TIV]

Thanks a million folks for all your great advise. PLEASE KEEP'EM COMING. This Forum is a treasure when something like this happens.  :musicboohoo:
I will not be able to go make some tests and try to repair it until the weekend. I will take a printout of this thread, and http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/bike-wont-start1.htm (great thread) with me and try if I can get it up and running over at mom's place. If not, I will have to haul it over to my garage and dig deeper.

[mystic red]

Grim, K 75 have Jetronic, not Motronic.....and quite different symptoms.
I would have started with checking the four pole tank connector (common problem source).

Inge, does the 75 have a side stand switch? If so, check that after the tank connector.

[JamesInCA]

Grim, K 75 have Jetronic, not Motronic.....and quite different symptoms.
I would have started with checking the four pole tank connector (common problem source).

Inge, does the 75 have a side stand switch? If so, check that after the tank connector.

No side stand switch.

Assuming the pump is not turning at all, the connector Inge referred to is the place to start. You can try applying 12V there directly to see if the pump turns. If not, the issue may be either the pump or the connection of the wires through the fuel level sender, i.e. through the plate at the bottom of the tank.

After disconnecting the connector, you could remove the pump and (taking care to stand well away from the pump, which will have fuel left in it), apply 12V to it on a bench to see if the pump itself is dead. You likely would already know to do this, but in any case: Attach the wires to the pump first, before attaching to the power source. Move away from the pump to attach them to the power source to avoid igniting any ejected fuel with arcing from the power source. Don't stand in line with either end of the pump.

[TIV]

Is the wiring through the "fuel level sender" a part of the unit, or is it possible to replace the wiring separately?

Is the "fuel injection relay" a special part or is it a universal part that can be bought at auto stores?

I will probably have a go at it this weekend and report my findings here.

[Inge K.]

The wires is soldered to the fuel sender terminals.

The FI relay is not a standard one, different pinout.

The usual problem with the before mentioned connector is that the diameter of
the female contacts have become to big, use a couple of toothpicks  or similar
pointed instrument to gently squeese these contacts back to the former diameter.

[TIV]

Finally got time to bring the bike home and take a look at it. It didn't take long to analyze the fault. The fuel pump is kaput. When I connect it to 12 VDC I can feel that it shivers as it's trying to start up but doesn't. I bench tested it out of the bike with a Variable DC Power Supply and here are the results.

Put it in a bucket so that it would not spit on me if it was OK


Here is the DC Power Supply console before I connected it to the pump


Here is the DC Power Supply console after I connected it to the pump


Guess I'll have to open my wallet!  :dunno

[WayneDW]

That's a cool instrument you have there.   What's the story behind that?

[TIV]

As you can see, the pump loads down the Voltage to 3,48 Volts when connected. This indicates that there is a short in the pump or that it is stuck.

The story on the cool device (Variable DC Power Supply) is that I have electronic background and make boutique guitar tube amplifiers on the side. Have some cool instruments associated with this.

[Grim]

Research before you buy a pump. There is some alternatives to the factory pump including $40 alternatives from common cars. I believe a Ford Mustang has a pump that is the right pressure and can be made to work.

[eyeofcy]

I had that problem with a fairly new pump.  If it's buzzing, that means that it's trying to turn.  I had a piece of debris stuck in the pump, preventing it from turning.

Try reversing the polarity to the pump which will make it run backwards.  Abter doing this several times, the pump freed itself and has been running fine ever since.  Good luck!

[kioolt]

What's the max current available from your power supply?  It my be that your power supply is protecting itself by dropping the voltage to it's max current of 2.4 amp.  I have an older variable DC power supply (probably 40 years old) that will drop the voltage if I either have the current limit set to low or if the current demand exceeds the max current of the supply, whichever is less.

[TIV]

Try reversing the polarity to the pump which will make it run backwards.  After doing this several times, the pump freed itself and has been running fine ever since.  Good luck!

This is certainly a good suggestion. I am going to be away until Monday, I will try this when I get back!

What's the max current available from your power supply?  It my be that your power supply is protecting itself by dropping the voltage to it's max current of 2.4 amp.  I have an older variable DC power supply (probably 40 years old) that will drop the voltage if I either have the current limit set to low or if the current demand exceeds the max current of the supply, whichever is less.

You have a very valid point there. It should of course act as a current limiter! I seldom use this tool because I´m usually working with very high voltages in my tube amps. For that I use a homemade current limiter with a bulb. I´ll have to check what the max current is on this one. Do you know how much current the fuel pump is supposed to draw under normal circumstances? Anyway, I will not buy a new pump until I´m sure that this one is gone south.

[kioolt]

What's the max current available from your power supply?  It my be that your power supply is protecting itself by dropping the voltage to it's max current of 2.4 amp.  I have an older variable DC power supply (probably 40 years old) that will drop the voltage if I either have the current limit set to low or if the current demand exceeds the max current of the supply, whichever is less.

You have a very valid point there. It should of course act as a current limiter! I seldom use this tool because I´m usually working with very high voltages in my tube amps. For that I use a homemade current limiter with a bulb. I´ll have to check what the max current is on this one. Do you know how much current the fuel pump is supposed to draw under normal circumstances? Anyway, I will not buy a new pump until I´m sure that this one is gone south.
[/quote]

Unfortunately I don't know what the proper current is for the fuel pump.  Looking at the pictures of your power supply I can't tell if you have the COARSE and FINE current limit knobs turned to max.  I would think that the max current of that power supply would be at least 5 amp.  It should be marked somewhere.

[JamesInCA]

If there is a question as to whether the pump is not running because the power supply can't deliver enough current, you could answer that by connecting the pump leads to the battery, correct? No need to over-complicate things....

[TIV]

No need to over-complicate things...

James, it's not a question of over-complicating things in this case, it´s a question of analyzing the fault and having fun and learning something new at the same time.  :2thumbup:

The Variable DC Power Supply gives out 0-30 DCV, 3A. I have tried connecting the pump straight to fully charged 32A battery in the bike again and again, forward and backwards and it does not turn. So, it´s gone south, and I´ll have to buy a new one. Motorworks in the UK sell them for 142 Pounds. They told me that they are able to sell these pumps at halve the price BMW does because they source them straight from Bosch. Same pump, different label on the box.

[TIV]

It´s alive! Got the new pump yesterday. It made my wallet considerably thinner. Tonight I installed it, poured in some gasoline and fired it up. Runs like a clock. Thanks to all for input, help and suggestions.  :riding:

[Big_B]

It´s alive! Got the new pump yesterday. It made my wallet considerably thinner. Tonight I installed it, poured in some gasoline and fired it up. Runs like a clock. Thanks to all for input, help and suggestions.  :riding:

Too bad you sprung for a BMW pump. The old ford mustang 4-cylinder pump works great for around $79. Been running one in my K1100 for well over a year with 20k plus miles!