RiderSite.com - Motorcycle Forums

More of a whinge as there are lots of posts about this but maybe something I say will trigger a thought in someone.

Fuel pump has lost power - it's not the pump - it's not the relays - it's not the tilt switch - not the kill switch - not the sidestand. I guess I'm down to a failed loom or ECU.

The weird thing is that I can measure a voltage across the pump's power supply terminals but it won't power a 3w lamp, I can't even detect a single mA passing through it with a bulb there. If I make a ground to the frame then it's all fine, bulb lights, pump runs.

If I check continuity between the battery and the pump's negative supply it's open circuit - SO HOW CAN I MEASURE VOLTAGE THERE?

Baffled tbh. Printing out a big copy of the wiring diagram to see where that negative supply wire goes. There is a post on Apriliaforum where someone has seen similar behaviour but I'm woolly on what their fix was.

Over the past few weeks the Fut's had a lot of use and has been intermittently stuttering and over-idling when warm, so I'm hoping those behaviours are a symptom of this failure and all will be well again for a few more weeks once resolved!

Any and all contributions are welcome!

diode pack?

I had something similar with the Falc a few years ago , it was indeed fuel pump failure.
Everything seemed fine, full voltage everywhere, all relays functioning, everything seemed in perfect order but the pump would cut out when it got warm and then re start when it had cooled.
Every time I removed the pump to bench test it it worked for prolonged periods.
The pumps internal earth had broken down, it worked on a bench test as I was providing an independent earth when bench testing.
It was sussed out by Griff@AP who told me the above and I stood no chance of working it out without diagnostics !
It was a major head fuck for me for months, see the above !
Hope this helps, try a substitute pump , good luck

I had something similar with the Falc a few years ago , it was indeed fuel pump failure.
Everything seemed fine, full voltage everywhere, all relays functioning, everything seemed in perfect order but the pump would cut out when it got warm and then re start when it had cooled.
Every time I removed the pump to bench test it it worked for prolonged periods.
The pumps internal earth had broken down, it worked on a bench test as I was providing an independent earth when bench testing.
It was sussed out by Griff@AP who told me the above and I stood no chance of working it out without diagnostics !
It was a major head fuck for me for months, see the above !
Hope this helps, try a substitute pump , good luck

fatboy wrote:I had something similar with the Falc a few years ago , it was indeed fuel pump failure.

I do have a brand new pump to hand but it really "appears" as if the return earth is being compromised by the ECU. Quite why it routes back there is anyone's guess (this is to a SAGEM ecu like the Capo uses as well). Maybe it's to monitor load or just for error logging? I do have the TuneECU harness that lets us lucky Fut and Capo riders have a proper delve. I'll see if I can get it to work with my new phone.

Laters and thanks

I traced the earth for the fuel.pump back to the Ecu - no problems there so the ECU is what's disconnecting it.

But here's the best lead I've had - apparently if there's any problems with the injector relay the pump won't run. Have a look at this:

https://photos.app.goo.gl/k89eP1JF7cM6oWbc8

Messy in there huh? I see if I can clean it up - of not Ultimate Parts is just a bus ride away.

Ropey as it is the disturbance has revived it. Pump's a pumping. I'll get a new one all the same.

https://photos.app.goo.gl/uvW7zHYfghGi5L1B6

Glad you nailed it, ( but you have got good at tracking down the weird ).
Relays do seem to suffer from dementia, no not moving/ might move when I can be arsed /will switch in an instant just to confuse you.
repeat the above in an intermittent order, just to confuse.
There is a way of checking relays/the speed they switch but after a 50 hour week and some beers my powers of recall are F/A

very good find mate, well done. I'd never have thought that sort of corrosion could get into a sealed relay.