3TJ runs for a couple of miles & duhduhduhh fuel pump?

[quinny-fzr4003tj]

Evening all!

My little 3tj is giving me some jip, which i secretly love :)

Rides fine & doesnt miss a beat but, after a couple of miles she stalls when ticking over at junctions & the like.

All fuel lines & the inline filter have been changed aswell as giving the tank a good clean out when i first got her some months back.

I've also replaced the stator as it wasnt sending a charge to my now binned battery which has obviously been replaced.

I've come to the conclusion that it is a fueling issue...maybe wrongly.
so my question tothe lovely people of 400GreyBikes is this:

Does the fuel pump run constantly if not what triggers it?

Cause to me (still alot to learn ) its only getting the initial pump when flipping the switch, and runs fine until my carbs are emptied??

the only other thing i could imagine is maybe my coils are overheating? <-- is that stupid?

Look forward to any replies as this giving me a sore head :))
Cheeers!

[Taggyd]

could just be dirty carbs/jets as you say it's more at idle so try cleaning the idle jets/checking the adjustment and mixture?

the fuel pump works until it gets enough pressure then stops. It should cut in as soon as the pressure drops (the fuel is used) if possible you could run it until it stops, open the carb drain to see if there is fuel in there. If not it's not getting enough fuel to the carbs so suspect the pump or wiring connection, but also the floats may not be letting enough fuel in (cutting it off too soon)
Try wiring the pump directly to the battery and taking it for a spin so that it is constantly fed power , this should show you if it the pump or the wiring that is the issue, my race bike did exactly the same and ended up doing this through a switch and in line fuse as the wiring has an issue with intermittent power and it gives me the option to shut it down to run the carbs dry if needs be.

[Evilchicken0]

Have you renewed the fuel filter ???
Might be an idea if you haven't.
Check the fuel filter on top of the fuel tap as well.

The silly thing could be the idle needs turning up a little - the floats could be a bit low. can you smell petrol at all - that could be the float bowl gaskets leaking slightly.

[blueranger]

Fuel pipe is kinking under tank if not the case then the fuel tap filter is blocked.... then try changing the fuel relay and then rule out the fuel pump..

[oollit]

Before you go mental stripping everything down to its base components, try opening the fuel cap after the bike stops to see if there is a vacuum inside the tank.
Might just be a blocked breather.

[quinny-fzr4003tj]

Thanks for the swift response guys!
all fuel filters & hoses have been changed fuel runs through these at a decent rate.
the original pipes did kink under the tank & werent a particularly nice fit. I thought changing those would solve it, does run alot nicer now though for the 3 or so miles it does haha

couldt smell any fuel atall before i took the tank off and the inline filter dripped abit so id say no to that one evil.
& it idles just around 1k which i thinks about right? it idles fine to start off with but it does start to fade and splutter after a while which again points towards fueling.

I've wired the pump up directly to a spare battery i have in my garage and runs fine, the connections seem good at both ends.. but then again i cant see in the loom but i doubt there would be an issue there 8) x-ray specs please?

I did intend on taking the carbs off and cleaning out the bowls due to the sate of the tank when i got it, but boys will boys ..couldnt resist getting her back together & on the road :] in the long run...wrong decision. Could i find any manuals info on the mukini carbs used on the 3tj? believe their something like bdst32's. Ihave looked in the past but no joy all i could get was the timing.

Think i'll give the carbs a thorough checking over tomorrow have some fun in the garage :)
but before that i think i'll try Oolits idea before i do (:

Still going to do the carbs though, want her to be at her best afterall.

Once again guys
NICE ONE (:
I'd be lost without this forum

[quinny-fzr4003tj]

ARGHHHH

today i added hose clips to the fuel lines just to ensure no air was entering or fuel leaving the system..

Removed the carbs and cleaned the blows & jets then reassembled and put back onto the bike.

she runs still but cuts out on tick over imediatley aswell as anything below 2k ..:/
electrical?????

[bendy3]

I had a similar problem, the fuel pipe was kinking when the fuel pipe got warm from the engine heat making the pipe go soft and then it would kink. Maybe something to think about?

[Evilchicken0]

Have a look at the tank breather.
So when the bike cuts out do the revs rise at all - that would the mixture weakening.

[quinny-fzr4003tj]

definately something to think about maybe i'll have to buy molded fuel lines. no change in the revs evil just dies instantly if it drops below 2k..ish.

I've ordered some coils so i'll try those and fiddle with the the fuel lines making sure its not kinking when theres heat put into them.

other than that im baffled, CDI units dont really go wrong do they?