Fuel Pump - intermittent fault

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DavShill · #1 Post by **DavShill** » Fri May 30, 2014 1:14 pm

Hi All - Falco just serviced and new battery and starter solenoid fitted recently. Test ride today and she stalled at the petrol station. I filled up then switched the ignition and I didn't get the usual sound of the fuel pump priming. left it a while, phoned the AA then went back to wait, tried her again and she fired up.

She did it again this morning. Rode for an hour, came home and she stalled on the drive. Switched her off and on again and no sound of the fuel pump priming. Lifted the tank and tried again and the pump primed. Did this a couple of time and it seems, tank down - no prime, tank up and pump primes. Tank down - pump sometimes primes and sometimes doesn't.

So do I bite the bullet and get it in to a dealer to fit a new fuel pump assembly, or do I keep tinkering. Any suggestions before I take it in?

Firestarter · #2 Post by **Firestarter** » Fri May 30, 2014 5:28 pm

Is there a relay on the circuit? Or dodgy wiring? Would look at that first

fatboy · #3 Post by **fatboy** » Fri May 30, 2014 6:03 pm

When the pump primes itself, this is actuated by the ecu, the pump will then cut out until it is under demand (engine running )
Im working my way slowly through wiring issues, the pump would not prime but will pump when power is applied to the pump wiring.
I had killed the pump relay and shut off relay by riding with a severed earth lead on the voltage reg/rectifier, I figured If Id killed the relays with a voltage spike then I probably killed the ecu....
Plugged a working ecu in and bzzzt, the pump primes now.
Thee fact that the bike runs seems to validate the pump relay so look for shit connections

#4 Post by **mangocrazy** » Fri May 30, 2014 8:08 pm

I seem to remember a thread on AF1 (Apriliaforum.com) where some poor guy had huge hassle with fuel pump wiring that was intermittently working. Or not. In the end the wiring fault was found inside the sealed portion of the fuel pump assembly, I seem to recall. Might be worth searching in the Falco section there.

It was a few years ago, I seem to recall.

DavShill · #5 Post by **DavShill** » Fri May 30, 2014 9:07 pm

thanks guys I'll keep searching before handing her over to the "mechanics".

flatlander · #6 Post by **flatlander** » Fri May 30, 2014 9:56 pm

Ok usual warning as in what I know about this stuff could be written on a piece of confetti and still leave room for the manufacturers name adress and family tree :)
That said if it is constant with the tank up and shit with it down I would look for pinched connections or something flexing. Along the circuit.
Now which one I ha FA idea :)

D-Rider · #7 Post by **D-Rider** » Fri May 30, 2014 10:57 pm

I'd certainly suspect wiring before the fuel pump.

As Graham says there was a case reported on AF1 where it turned out to be wiring inside the tank - so if checking the external wiring doesn't reveal it, remember there are more places to look.

A right PITA though.

blinkey501 · #8 Post by **blinkey501** » Sat May 31, 2014 4:56 am

The main plug for the fuel pump is under the riders seat. Check for a good connection there too.

DavShill · #9 Post by **DavShill** » Sat May 31, 2014 8:36 am

thanks, I'll have another look today.

DavShill · #10 Post by **DavShill** » Sat May 31, 2014 5:05 pm

Ok so been out again this afternoon and she ran, started and stopped and restarted fine, hot and cold.

I received Gabro's chip a couple of weeks ago so took the opportunity t fit it this afternoon. When I swapped the chips and turned on the ignition there's a constant clicking from one of the relays under the seat pod..... and its the Fuel Pump relay.

Firstly should it do this just because I swapped the chip and is it just doing some electronic trickery while it recalibrates stuff cos of the new chip? Or is it wrong?

Secondly I'm thinking I may just fit a new fuel pump relay just in case that's the intermittent problem.

Thoughts please.

Swapped the chips back again and she runs just fine on the stock chip.

fatboy · #11 Post by **fatboy** » Sat May 31, 2014 6:34 pm

You are describing very similar symptoms to my own hassles which started after fitting a Gabro eprom but in honesty there were other electrical issues.
I was getting a constant clicking from the shut off relay, it was going mad. This is next to the pump relay, the shut off relay being the first of 2 identical relays. I had a bad earth on voltage regulator and the engine breather pipe dumped oil all over wiring beneath air box...
2 relays,2 ECU's and a tip over switch later...
PS vv easy to test both of the relays
Your problems seem to point to ECU, eprom or wiring, been there,done that this afternoon

Falcopops · #12 Post by **Falcopops** » Tue Jun 03, 2014 3:11 am

Hey Dave,

best to sort out one problem at a time, so I'd suggest keeping the old chip in for the moment until the fuel pump is sorted.

There are documented issues with the wiring failing where it passes through a plug of potting compound into the tank, have a search on AF1, it's happened to more than one person and there were some nice pics of the failure. DIY raipairs are possible and the materials used were also posted.

The fact that there was a difference if the tank was up or down makes me suspect this is the issue mentioned above.

Good luck.

Moose · #13 Post by **Moose** » Tue Jun 03, 2014 8:18 am

Hi Dave,

If all else fails and before "taking to a dealer", I have a spare fuel pump in my garage you could try.

#14 Post by **mangocrazy** » Tue Jun 03, 2014 3:03 pm

Falcopops wrote:There are documented issues with the wiring failing where it passes through a plug of potting compound into the tank, have a search on AF1, it's happened to more than one person and there were some nice pics of the failure. DIY raipairs are possible and the materials used were also posted.

And if you find the thread(s) on AF1, please post them up here. I suspect this may be an accident waiting to happen to a few of us.

fatboy · #15 Post by **fatboy** » Tue Jun 03, 2014 7:15 pm

PLEASE READ THIS before you part with a load of money you don't need to part with...
I have had a fuel pump fail on me, it failed to earth itself internally but worked perfectly every time I removed it from the tank and bench tested it on a remote power supply, never would have found it without diagnostics.
PLEASE NOTE, the pump never failed to prime, only cutting out when it got hot, the pump priming is initiated by the ECU.
As you mentioned the pump primes when you raise the tank you may well have wiring issues.
Before you give a stealer all your cash give Griff aring 01827 285500