Rentonone
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| posted on 9/10/20 at 12:19 PM |
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Fireblade engine overfuelling problem.
Hi guys,
I’ve got a problem on my 919 Fireblade powered tarmac buggy.
I’ve rebuilt the carbs and the buggy runs absolutely great when the fuel is gravity fed, but due to the fuel tank position it runs out of fuel with
about 3/4 of a tank left in.
So I’ve fitted a Fireblade fuel pump from eBay (not an original)
The pump clicks really fast, and then slows down when the pressure builds up, it then clicks about ever second.
The engine starts and runs ok for about 10 seconds then really starts spluttering, if I switch the pump off whilst it’s running it clears out and runs
fine again.
So it’s definitely the pump over fuelling for some reason, what could this be guys?
I run a fuel tap straight off the tank, with a Fireblade filter and then the pump.
Thanks James
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gingerprince
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| posted on 9/10/20 at 12:25 PM |
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Is the pump definitely for a carbed blade not a later injection blade?
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Rentonone
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| posted on 9/10/20 at 12:33 PM |
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quote:
Originally posted by gingerprince
Is the pump definitely for a carbed blade not a later injection blade?
Yes mate, here’s a link to it.
https://www.ebay.co.uk/itm/151994994988
Cheers James
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Rentonone
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| posted on 9/10/20 at 04:51 PM |
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Is the pump meant to keep clicking? It seems to build up pressure but still clicks every second or so?
I’ve only got it wired to a switch and relay, I might wire it to the coils for its trigger, but it’s still over fuelling when ticking over.
Could it be that it’s a cheap eBay pump, maybe I need an original?
Cheers James
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Schrodinger
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| posted on 9/10/20 at 05:22 PM |
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I've read something recently on another site on a similar theme and it was suggested that on bike carbs there are some o rings in the float bowl
that seldom get changed and will let the fuel by, it could be worth a check.
Keith
Aviemore
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gremlin1234
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| posted on 9/10/20 at 06:30 PM |
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quote:
Originally posted by Schrodinger
I've read something recently on another site on a similar theme and it was suggested that on bike carbs there are some o rings in the float bowl
that seldom get changed and will let the fuel by, it could be worth a check.
and many 'o' rings suffer with modern fuel
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Rentonone
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| posted on 9/10/20 at 06:56 PM |
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quote:
Originally posted by Schrodinger
I've read something recently on another site on a similar theme and it was suggested that on bike carbs there are some o rings in the float bowl
that seldom get changed and will let the fuel by, it could be worth a check.
I’ll check them out Mate, I’ve already fitted new ones, but maybe one has dislodged.
Cheers James
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Rentonone
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| posted on 9/10/20 at 07:36 PM |
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It does run fine when the fuel is gravity fed though, wouldn’t the o rings cause a problem in this case if they were faulty?
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Dingz
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| posted on 9/10/20 at 07:47 PM |
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Could it be one or more float needles not sealing properly? If not you may just need a pressure regulator.
Phoned the local ramblers club today, but the bloke who answered just
went on and on.
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ReMan
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| posted on 9/10/20 at 09:09 PM |
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You should not need a regulator if its the right pump.
Ticking fast then dropping to 1/sec sounds right, but it should stop altogether once the float bowls are full if not running, can you see fule
leaking out?
So if it is not, then likely a needle is not seating and its flooding it, you ought to be able to see tghis with a very wet plug i'd have
thought?
www.plusnine.co.uk
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Deckman001
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| posted on 10/10/20 at 07:41 AM |
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Hi, I can confirm that when Bike engine carbs fed are from a bike fuel pump the pump does run up fast on start up to fill the float bowls, it the
slows to a stop if the engine isn’t kicked into life.
Therefore if your pump is continuously clicking, it must be carrying on pushing more fuel into the carbs as it is pressure triggered so not an
electrical spurred event. So it can be plainly a switched power source so that wouldn’t be my first place to look.
If the pump is at fault, it could only be over pressurising the carbs.
I’d definitely start at the plugs to see if any are wet and over fuelled. Then take the carbs off and check them over again.
Jason
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Rentonone
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| posted on 10/10/20 at 08:31 AM |
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Thanks guys, I’ll fire it up later and check out the plugs.
I might take the pipe off the pump see if it stops pumping with my finger over the end.
James
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Rentonone
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| posted on 10/10/20 at 08:33 AM |
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Also, what is the smaller pipe on the pump for? Is this just a breather? It’s currently just open ended.
James
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