Fuel pump or red Herring ???

[Spud]

2003 Twin Spark GS adventure...
Had occasional issues with non starting and no fuel pump priming noises...
Being ridden down the road and just spluttered a few times then Died.

Power at the oblong connector (12v) for approx 1 second on initial ignition turn on.
No fuel pump prime or noise.

Fuel pump replaced with used one from Sherlocks, fault remains the same ..
Old pump tested on 12v and works ok. Tested circuit from plug to pump and shows continuous circuit ...

Any suggestions as to probable cause, or what to test next ?
Hall sensor wiring ? Scratching head a little

Thanks in advance

 

[NeilDD]

Spud,
The sequence as I understand it is;
Power on- 12V supplied to pump to prime the system
Then when engine starts the pump is governed by HES and Motronic

This points to the pump being questionable, check the condition of the flat 4-way connector on the RHS of the tank, looking for corrosion etc but there is a potential problem with the HES,
Have a careful look at the wiring from the HES, especially if it is the original, as the OEM spec will go brittle with age.

Best of luck

 

[Spud]

Spud,
The sequence as I understand it is;
Power on- 12V supplied to pump to prime the system
Then when engine starts the pump is governed by HES and Motronic

This points to the pump being questionable, check the condition of the flat 4-way connector on the RHS of the tank, looking for corrosion etc but there is a potential problem with the HES,
Have a careful look at the wiring from the HES, especially if it is the original, as the OEM spec will go brittle with age.

Best of luck

Thanks Neil. Tried two pumps with the same result. Definite 12v on initial ignition on, but no priming noise. Tested the first pump (replaced) and it works fine with 12v directly applied to it.....

 

[NeilDD]

Deffo sounds as if the HES has died.
Have a search for NOID light, it will show you how to make a simple tester for the HES

 

[Ian J Hartley]

You need A good 12v and a good earth. Without either the pump won’t run.

You seem to have checked the 12v, have you checked you have a good sound earth at the tank connector.

 

[Ian J Hartley]

The initial priming of the fuel rail has nothing to do with the HES. It’s a function of the Motronic to provide initial fuel pressure prior to start.

Once the engine rotates, then the HES comes into play........

 

[Ian J Hartley]

Also while I’m thinking about it, swop the fuel pump relay. It might have poor contacts and gone resistive. Which would have a greater effect dropping more voltage with the higher current draw of the pump as opposed to measuring with a DVM.

That’s it for now.

 

[West coast gser]

2003 Twin Spark GS adventure...
Had occasional issues with non starting and no fuel pump priming noises...
Being ridden down the road and just spluttered a few times then Died.

Power at the oblong connector (12v) for approx 1 second on initial ignition turn on.
No fuel pump prime or noise.

Fuel pump replaced with used one from Sherlocks, fault remains the same ..
Old pump tested on 12v and works ok. Tested circuit from plug to pump and shows continuous circuit ...

Any suggestions as to probable cause, or what to test next ?
Hall sensor wiring ? Scratching head a little

Thanks in advance

Side stand switch playing up ? Kawasaki used to be bad for that ..or neutral switch playing up..?

 

[Beak Freak]

DAMHIK!

Have you checked the wiring loom that goes round the headstock? I had a similar issue and it was a break in one of the wires there. You can sometimes get it to work by turning the handlebars, not a solution, but it does give a good sign.

Sorry, to add to your list of possible issues, electrics!

 

[Spud]

A big thanks to everyone, this wasn't my bike, but we did get it sorted. Ian gets the prize, as after swapping the pump relay out of mine into the "poorly' bike, it fired first time. !!

Now a question, as I'm not the greatest with electrical stuff..

Why did we get an initial (1 second or so) 12 volts at the supply leads when we tested it, but the pump didn't work ? I'm a little confused.

 

[Andi_archer]

It may be the contacts are worn or prone to vibration which affects the supply voltage under load .

 

[Spud]

Hi Andi,
Thanks for the reply. Having just done some digging into older threads, I think the issue here is that there wasn't 12v constant when you pressed the starter motor, which is apparently what you should have (I missed, but I'm learning !!)

Still confused why no response from the pump to the initial momentary 12volts though ......

 

[DrFarkoff]

Hi Andi,
Thanks for the reply. Having just done some digging into older threads, I think the issue here is that there wasn't 12v constant when you pressed the starter motor, which is apparently what you should have (I missed, but I'm learning !!)

Still confused why no response from the pump to the initial momentary 12volts though ......

volts not amps ...

You Always test with a load e.g. a bulb not an LED

12 V at very minimal amps will show on a Mutlimeter but it will not light a bulb so basically it sends the voltage but there is no oooomph behind it to spin the fuel pump

 

[Ian J Hartley]

Thank you Spud for coming back and letting us know how you got on.

Many don’t which is annoying to say the least.

Anyway glad to hear it’s all sorted and your mates back on the road.


Ian