Odd one....

King Rat

Well-known member
UKGSer Subscriber
Joined
Nov 18, 2006
Messages
12,070
Reaction score
1,430
Location
Uttoxeter, England
Bike running perfectly sweetly.
Parked up for 2 days... come to restart and there is no fuel pump hum.
Battery not brilliant, so on charge all day.
Try this evening, lights bright, still no fuel pump hum, but bike spins very rapidly, so plenty of electrons available to really whizz the starter motor.
Scratch head, check fuses. All fuses fine - checked by eye but also with a buzzer tester. Fuel pump is number 6, that fuse swapped with the other red one - still no fuel pump hum.

Can a fuel pump really fail while it is switched off? Working perfectly , then next time to fire up just fail completely... is that a common thing with them, or do they normally fade away with a bit of warning? Trouble is there is 28 litres of fuel in the damn tank, because I fuelled up just before getting home last time and the petrol pump is only about 800 yards from home! Typical.

Ignition switch is fine - all functions are fine with that.

What would your bets be on guys?
 
Or no supply to it.

So, where does the fuel pump connector live? Is it the big one on the right that you have to release to take the tank off? I know there are a plethora of wires going to and from it, but no idea what they are for (I gave my manual to the guy who bought my other one :blast )
 
Next one - where is a good place to get a fuel pump from please? Just in case I have to buy a new one... I need the bike to get to work next week. Pray the 650 works
 
Could be pump,could be hall sensor,
4way block connector R /h side under plastic side panel.
Thick brown wire is earth
Other thick wire is pump feed,(can’t remember colour.)test light or meter to this wire and crank the motor should have 12v.
Check this 1st.
 
Next one - where is a good place to get a fuel pump from please? Just in case I have to buy a new one... I need the bike to get to work next week. Pray the 650 works


You can get a replacement pump for notalotacash,it’s the same fitment as some Audi,s
Look up the original pt no ,and search on eBay.
 
Did you check the supply to the pump as suggested it may be the safety circuit is preventing the pump running
 
Had exactly same problem on my lads 1150. If the Hall Sensor goes awol the safety stops the fuel pump working ... otherwise it would be spinning the motor over and filling the cylinders with petrol :eek:

The Hall Sensor 'produces' the spark at the right time ... it's located under the front cover, wire up to under the tank if I remember correctly. I went and obtained one, returned to son and fitted at the side of the road :D

:beerjug:
 
Before you go jumping down rabbit holes check the fundamentals.

Have you checked there is 12v supply to the fuel tank connector when you crank the engine as “Mikeyboy” suggests.

If No, then swop the Fuel pump relay, and try again.

To confirm a pump failure

Try and feed 12v direct to the Fuel pump at the tank connnector. If the pump doesn’t run then it’s the pump or a break in the tank wiring.

If the pump runs with direct feed of 12volts, then your fault is else where.

Ian
 
Before you go jumping down rabbit holes check the fundamentals.

Have you checked there is 12v supply to the fuel tank connector when you crank the engine as “Mikeyboy” suggests.

If No, then swop the Fuel pump relay, and try again.

To confirm a pump failure

Try and feed 12v direct to the Fuel pump at the tank connnector. If the pump doesn’t run then it’s the pump or a break in the tank wiring.

If the pump runs with direct feed of 12volts, then your fault is else where.

Ian

I agree with the above advice:thumb..................Grizzly:beerjug:
 
Before you go jumping down rabbit holes check the fundamentals.

Have you checked there is 12v supply to the fuel tank connector when you crank the engine as “Mikeyboy” suggests.

If No, then swop the Fuel pump relay, and try again.

To confirm a pump failure

Try and feed 12v direct to the Fuel pump at the tank connnector. If the pump doesn’t run then it’s the pump or a break in the tank wiring.

If the pump runs with direct feed of 12volts, then your fault is else where.

Ian

How do I check if it has 12V ? You need special instruments to do this.
When you say swap the fuel pump relay - what with?

I am off to Foley Motorcycles in Stoke in a minute. Andy now owns it and I have his trailer. He was an RAF weapons and electrical technician - he has all sorts of fancy testing kit, oxilloscopes for measuring micro currents and all sorts of stuff... way beyond my understanding. I am just getting my breath back - I dropped the bike trying to push it onto the trailer. I'm knackered from picking it up. It is on now and strapped down. I shall tell him all your suggestions. I have written them down and will take them. They might help.

Hopefully it will be something simple and not too expensive - thankfully the 650 fired straight up last night, so at least I can get to work. :thumby:
 
How do I check if it has 12V ? You need special instruments to do this.
When you say swap the fuel pump relay - what with?

I am off to Foley Motorcycles in Stoke in a minute. Andy now owns it and I have his trailer. He was an RAF weapons and electrical technician - he has all sorts of fancy testing kit, oxilloscopes for measuring micro currents and all sorts of stuff... way beyond my understanding. I am just getting my breath back - I dropped the bike trying to push it onto the trailer. I'm knackered from picking it up. It is on now and strapped down. I shall tell him all your suggestions. I have written them down and will take them. They might help.

Hopefully it will be something simple and not too expensive - thankfully the 650 fired straight up last night, so at least I can get to work. :thumby:


Ok well the Fuel pump relay is the small black one indicated. You can swap it with the horn relay, they are Identical.

You could disconnect the tank connector and feed 12v direct to the pump. Brown wire earth Green/white wire +12v. If the pump runs then the pump is good.
 

Attachments

  • 87890318-FA1C-4259-861F-0CEAB02FAC70.jpg
    87890318-FA1C-4259-861F-0CEAB02FAC70.jpg
    234 KB · Views: 391
Had exactly same problem on my lads 1150. If the Hall Sensor goes awol the safety stops the fuel pump working ... otherwise it would be spinning the motor over and filling the cylinders with petrol :eek:

No it wouldn't.. The fuel injectors would need to be permanently open to let fuel past. The injectors also need a signal from the hall sensors in the same way as a spark plug gets a brief electrical signal and sparks to the injectors work in much the same way, the injectors receive a signal and open briefly allowing fuel to pass into the cylinder.

If a fuel pump is permanently running the fuel just get returned to the fuel tank via the mechanical pressure regulator.
That's also how you empty a fuel tank if you need to drain it. A live to the fuel pump with a hose attached to the fuel return pipe and the fuel gets pumped out until empty.
 
No it wouldn't.. The fuel injectors would need to be permanently open to let fuel past. The injectors also need a signal from the hall sensors in the same way as a spark plug gets a brief electrical signal and sparks to the injectors work in much the same way, the injectors receive a signal and open briefly allowing fuel to pass into the cylinder.

If a fuel pump is permanently running the fuel just get returned to the fuel tank via the mechanical pressure regulator.
That's also how you empty a fuel tank if you need to drain it. A live to the fuel pump with a hose attached to the fuel return pipe and the fuel gets pumped out until empty.

We'll see :D

My info came from a BMW Technician ... and was spot on!

Lads bike wouldn't start, just turned over. It had started on the deck of the ferry, got him down to passport control, but then wouldn't start.

Check ... No fuel pump hum, plug out, coil stick back on plug, plug held to earth, no spark = Hall Sensor!

I went and got one, not difficult to fit, had to talk my way back through Passport Control to t'other side :D

Well I did get all round Belgium, Luxembourg and Germany in October with an out of date passport :D

Mark up the position of the Hall Sensor (it's slotted, to fine tune ignition timing) and fit the new one in the same position. Ignition timing will be as near as was to make no difference.

Started straight away.

IF the Hall Sensor packs in the fuel pump will not work otherwise it would fill the cylinders with petrol, with possible theatrical results :D

If you're draining a tank you aren't filling the cylinders, you have a tube from the pump side into the receptacle you're emptying the tank in to!

:beerjug:
 
I'm guessing Mickey removed the exhaust push rods for the cylinders to fill with fuel..........
 
No it wouldn't.. The fuel injectors would need to be permanently open to let fuel past. The injectors also need a signal from the hall sensors in the same way as a spark plug gets a brief electrical signal and sparks to the injectors work in much the same way, the injectors receive a signal and open briefly allowing fuel to pass into the cylinder.

If a fuel pump is permanently running the fuel just get returned to the fuel tank via the mechanical pressure regulator.
That's also how you empty a fuel tank if you need to drain it. A live to the fuel pump with a hose attached to the fuel return pipe and the fuel gets pumped out until empty.


I don't think he heard you :D
 


Back
Top Bottom