fuel issues

Message

XRPhilagain · #1 Post by **XRPhilagain** » Wed Jan 28, 2015 11:02 pm

Hi All, not been on here for quite a while (was XRPhil) the Falco has been parked up for a couple of years, and I am now putting it back on the road.

Having a problem at present in that it wont start, or stay started! it will start and run for around 5 seconds, just while the fuel system primes then instantly dies. I can make it run by spraying brake cleaner in the injectors, but soon I i stop it dies.

I have put on new throttle bodies and injectors, but no difference.
its obviously a fuel issue but i,m not sure where? thoughts are it could be fuel pump, something to do with priming and pressure. could be ECU?
Over to you guys for some ideas or has anyone had the same issues?

Aladinsaneuk · #2 Post by **Aladinsaneuk** » Wed Jan 28, 2015 11:12 pm

You have changed the fuel??

(It degrades very quickly....)

Fresh fuel and some redex

Also, try running with the petrol cap open

GregD-UK · #3 Post by **GregD-UK** » Thu Jan 29, 2015 6:25 pm

Hi all,

Fuel only good for 30 days or so. Suck out the old stuff and replace with fresh...

blinkey501 · #4 Post by **blinkey501** » Thu Jan 29, 2015 6:34 pm

Welcome to the forum Phil.

What they said

XRPhilagain · #5 Post by **XRPhilagain** » Thu Jan 29, 2015 6:52 pm

Changed the fuel, ran it with cap open, changed throttle bodies with injectors and regulator. it only starts if i hit the button as soon as I turn the ignition on- ie whilst fuel pump is priming, then it dies if I wait till pump has primed and then try it will not start, i can run it if I spray solvent into the injectors.
I can only assume its not getting fuel once its finished priming.

XRPhilagain · #6 Post by **XRPhilagain** » Thu Jan 29, 2015 6:55 pm

Oh and thanks for the welcome and hi

i,m not actually a new member as such- was on here before as Xr phil but coulndt sign back in as me! Lol

squadron Nero · #7 Post by **squadron Nero** » Thu Jan 29, 2015 7:01 pm

GregD-UK wrote:Hi all,

Fuel only good for 30 days or so. Suck out the old stuff and replace with fresh...

Really!?

I've never had a problem with fuel going 'stale' on many vehicles / lawn mowers / chainsaws that have sat for longer sometimes a lot, a very lot longer than 30 days.

Obiwan Kenobi · #8 Post by **Obiwan Kenobi** » Fri Jan 30, 2015 9:44 am

Fuel still works after time, but goes stale and can start to turn to gum in fuel lines and carbs.

Sounds like a fuel starvation issue to me: fuel line to injectors gummed up..?

Falcopops · #9 Post by **Falcopops** » Fri Jan 30, 2015 9:56 am

Have a look in the tank as the pump is priming and see if there is a split in the hose on the pump.

There have been known to split and cause problems similar to your's

XRPhilagain · #10 Post by **XRPhilagain** » Fri Jan 30, 2015 7:30 pm

I will check but I presume it would be leaking petrol - which it isnt. problem is I dont know enough about this part of the bike! seems strange that it will run for 5-7 secs whilst it primes then not at all- obviously the fuel supply is `opening` but soon as it finishes priming seems like it closes again.
not even sure if I am looking for a Mechanical or electrical issue.

Running on the basis that every other problem I have had someone else on here has also had hope someone can shed some light on it!

fatboy · #11 Post by **fatboy** » Fri Jan 30, 2015 7:46 pm

Could be fuel pump/ tilt switch or pressure regulator.
As the fuel pump primes it is not the ecu, this is initiated by the ecu.
Check that the sliding contact in the tilt/tip switch is not stuck.
May be starter interlock diode ?
my bike will actually run with tip switch dissconnected but will flash up EFI on dash.

Wally · #12 Post by **Wally** » Fri Jan 30, 2015 11:10 pm

I may be wrong but I think these statements may lead somewhere

XRPhilagain wrote: 1) it only starts if i hit the button as soon as I turn the ignition on- ie whilst fuel pump is priming, then it dies

2) if I wait till pump has primed and then try it will not start,

3) I can only assume its not getting fuel once its finished priming.

1) This proves it will run until the fuel pressure drops. We need to confirm if it does drop? This could be either - a) loss of pressure due to failed pressure regulator returning fuel to the tank but this would probably prevent a start unless the pump can overcome the leak whilst the pump is running. b) loss of pressure due to a leak on the system (which may be inside the tank as mentioned by Falcopops) this again would probably prevent a start unless the pump can overcome the leak whilst the pump is running. c) the pump is not continuing to run after the engine has started.

2) Without the engine running, the fuel pressure after it has primed should hold at around 3 bar for at least 10 mins if all is good. Mine will hold pressure for at least 45 mins. So in theory it should start after say 1 minute of the pump having primed. If yours does not it may be the pressure has reduced quite quickly to an amount that will prevent a start. Again we need to confirm any pressure drop?

3) this could only be because the fuel pressure has dropped due to pump not running. So here we need to conform the pump is still running. Again this could be confirmed by fuel pressure.

There could be other causes but from what you have said I would want to confirm these things first.

Have you any way of checking the fuel pump live supply with a test light? The same live goes to the pump and both injectors from the pump relay, a green/black wire. The green/black wire should become live when the pump primes and go off after the pump stops priming and if the engine has started it should continue to be live. This would be a good first test as without a pressure test valve and gauge it will be dificult to monitor fuel pressure.

Wally

Falcopops · #13 Post by **Falcopops** » Sat Jan 31, 2015 2:15 am

Good call Wally.

I've not tried this, but if you disconnect the fuel return line while your trying to start i'd expect fuel to pump out, this could help confirm if the fuel pump is running. Won't tell you the pressure though.

Make sure you put the fuel line in a clean receptacle so you can reuse the fuel and ensure it's nice and stable or you'll be covered in it.

#14 Post by **mangocrazy** » Sat Jan 31, 2015 1:35 pm

My first port of call would be to try and find a known working fuel pump and perform substitution testing. If that checks out OK, do the same with fuel regulator. If that fails, then I'd suggest replacing the submerged fuel hose in the tank with new fuel hose of the correct specification (i.e. FI submersible hose).

I'd hope that after those 3 steps have been followed the fault would either have been cleared, or a better indication of where the fault lies will have shown itself.

XRPhilagain · #15 Post by **XRPhilagain** » Sat Jan 31, 2015 3:16 pm

This is why this forum is THE BEST. always lots of good answers from people who know what they are talking about! just got dressed up warm as snowing and went to garage for a long session to go through the suggestions-
started with easy stuff, disconected relays at back, then to tip over sensor- gave it a shake, it rattled, didnt expect that but hey presto BIKE STARTED!
It ran for a while then died and returned to old problem, removed sensor and bike working fine now!
Many thanks all

next job, replace seal in clutch slave- anyone know the size? i will have a search and repost it as a new topic, if not- I may even have posted myself as did it one before! that would be Ironic Lol