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Lhs Cylinder Constantly Flooding


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#1 Beancounter

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Posted 25 August 2014 - 01:23 pm

Hello All,

 

Myself and my mechanic mate are pulling our hair out over this current problem - the left hand side spark plug seems to get flooded and won't spark.  There is also a very strong smell of petrol from the exhaust fumes, I assume because it is unburnt fuel.

 

Problem first occurred last Wednesday night when leaving work.  Engine was running fine as I lef the car park but a few minutes later, whilst pulling away from some traffic lights it felt as though the bike was running out of fuel (which it wasn't).  Had to nurse the bike home on one cylinder.  On my way to my mate's place yesterday, the second cylinder would kick in at around 5k rpm and would run normally.

 

We have checked the following so far:

  • ignition coils - fine and giving a good spark;
  • plug gap - fine
  • float level/fuel height - fine;
  • carb rubbers - no apparent splits;
  • inlet manifold rubbers - no leaks and screws tightening properly;
  • carbs have been blown through at least three times - as far as we can see everything is clear;
  • floats and float needles swapped between carbs - still same problem on LHS only.

The only thing we can now think to check are the valve clearances (last done approx. 15,000 miles ago) but I'd appreciate any steers you guys can give in case we're not seeing anything obvious.

 

Thanks,

 

:)

 

 

 

 

 

 

 

 

 

 



#2 dicky1

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Posted 25 August 2014 - 04:11 pm

I had a similar problem some years ba

ck which turned out to be a dodgy plug lead which only showed the problem when engine was under load.

Try swapping the leads over and see the problem moves to the other cylinder if not that do a similar check by swapping the spark plugs over.


Edited by dicky1, 25 August 2014 - 04:20 pm.

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#3 Studley Ramrod

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Posted 25 August 2014 - 04:15 pm

It could be a faulty/worn fuel pump.  There's a vac pipe that runs from the pump to an inlet stub on the cylinder intake.  If the pump diaphragm is worn or pinholed, fuel collects in the vac pipe and then runs straight into the cylinder, flooding it.


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#4 Beancounter

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Posted 25 August 2014 - 07:41 pm

I had a similar problem some years ba

ck which turned out to be a dodgy plug lead which only showed the problem when engine was under load.

Try swapping the leads over and see the problem moves to the other cylinder if not that do a similar check by swapping the spark plugs over.

 

Good call.  LHS wasn't attached to the plug cap very well so we've replaced both leads.

 

It could be a faulty/worn fuel pump.  There's a vac pipe that runs from the pump to an inlet stub on the cylinder intake.  If the pump diaphragm is worn or pinholed, fuel collects in the vac pipe and then runs straight into the cylinder, flooding it.

 

This might be more like it....  The problem today only reared its head when fuelling through the pump.  If we used gravity from a remote fuel cell straight to the carb, the bike ran fine.  Put if back on to the pump/tank supply and it was back to running only on the RHS cylinder.  We did this a number of times (more than 10) with the same result.

 

We took the fuel pump apart and couldn't spot anything untoward.

 

One question, if the diaphragm was knackered, wouldn't that flood both cylinders?

 

Thanks again folks. :)



#5 dapleb

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Posted 25 August 2014 - 07:49 pm

Beany, ewe can make a test diagramaflam ooot of a sheet of arsey tates.  Worthwhile even if only for testing porpoises.


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#6 bigmick1981

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Posted 25 August 2014 - 08:57 pm

Sound similar to my problem see thread latest tale of woah . Tried running on both on position and reserve ?

#7 TYREDNGRUMPEE

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Posted 25 August 2014 - 10:33 pm

 

One question, if the diaphragm was knackered, wouldn't that flood both cylinders?

 

 

Nope. Bee Crows the vacuum pipe only runs from the lh Carp inlet back to the pump itself.

Worth taking into consideration the suckage between the two, which could be sufficient to suck fuel past.

Any sign of fuel in the vacuum pipe?

The pipes are connected correctly? Wouldn't be the first time.


Edited by TYREDNGRUMPEE, 25 August 2014 - 10:37 pm.


#8 Beancounter

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Posted 27 August 2014 - 08:06 am

Beany, ewe can make a test diagramaflam ooot of a sheet of arsey tates.  Worthwhile even if only for testing porpoises.

 

Thanks dappers. I'm guessing that you just put the acetate over the diaphragm? :)

 

Sound similar to my problem see thread latest tale of woah . Tried running on both on position and reserve ?

 

Aye, same problem regardless of reserve or main. :(  Tis only when by-passing the pump that both cylinders run.

 

 

Nope. Bee Crows the vacuum pipe only runs from the lh Carp inlet back to the pump itself.

Worth taking into consideration the suckage between the two, which could be sufficient to suck fuel past.

Any sign of fuel in the vacuum pipe?

The pipes are connected correctly? Wouldn't be the first time.

 

No sign of fuel in th vacuum pipe and everything looks to be connected correctly.

 

I forgot to mention a couple of things:

 

  1. When we tested the fuel pump to see if it was pulling fuel, at tickover everything looked to be fine with fuel pumping into our catch-jug.  Under load however and the fuel stopped flowing, hence why we thought it was the pump and then proceeded to dismantle it.
  2. A few months ago I suffered hydraulic lock on the same cylinder.  Got to work fine one morning and then that evening the bike refused start, same symptoms as a dead battery.  Managed to bump start and get home.  After testing solenoid, charging battery etc. and on the advice of my mechanic mate I removed the plugs and spun the engin by hand and a few dessert spoons of fuel popped out.  I let the plug and chamber dry andthe bike started.  I've been meaning to investigate further but time has not been on my side and as long as I turned the fuel tap off the bike would start no problem.  FWIW there' been no noticeable drop in fuel economy.
  3. Compression was tested at the weekend, 155psi on both cylinders, down from 170/180 from new so it looks as though new rings are needed.

Once again, thanks for your vauled input. :)



#9 dapleb

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Posted 27 August 2014 - 08:20 am

 

Thanks dappers. I'm guessing that you just put the acetate over the diaphragm? :)

 

The diagramaflam bit should be clear and flat.....but they go clear and flappy.  If it is starting to look bulbous then its pooped.  Takes 5mins to make a new wan once you have some arsey tates.  Teck old oot, put new in....see if it makes a difference.  I am still using my "test" home made diagramaflam prolly 2000miles on now.  Though someone reported that they had problems with leafing theirs in on a permanent basis.  Either way still ferry useful as a test afore splodging oot on a new fool pamp (or not).


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Doin valve clearances? Use dappers valve shim exchange program and the job will be carroty - Free (other than you postin me yer shims) for sporting members.

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#10 Studley Ramrod

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Posted 27 August 2014 - 02:12 pm

:wifgeni:

 

Do you turn the fuel tap off when you park it up ?  Also worth checking that the fuel tap actually stops fuel when it's turned off as the gasket can wear too.


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#11 Beancounter

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Posted 27 August 2014 - 03:33 pm

 

The diagramaflam bit should be clear and flat.....but they go clear and flappy.  If it is starting to look bulbous then its pooped.  Takes 5mins to make a new wan once you have some arsey tates.  Teck old oot, put new in....see if it makes a difference.  I am still using my "test" home made diagramaflam prolly 2000miles on now.  Though someone reported that they had problems with leafing theirs in on a permanent basis.  Either way still ferry useful as a test afore splodging oot on a new fool pamp (or not).

 

Thanks mate.  Will probably have to wait until the weekend to give that a try. :)

 

:wifgeni:

 

Do you turn the fuel tap off when you park it up ?  Also worth checking that the fuel tap actually stops fuel when it's turned off as the gasket can wear too.

 

Never used to but I do now. :)



#12 Beancounter

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Posted 29 August 2014 - 03:45 pm

:wifgeni:

 

Do you turn the fuel tap off when you park it up ?  Also worth checking that the fuel tap actually stops fuel when it's turned off as the gasket can wear too.

 

Fuel tap gasket is fine.  All fingers now point to a knackered fuel pump as there is fuel in the vacuum pipe on the LHS cylinder.

 

ISTR that you can fit an electric fuel pump instead of the mechanical one, sure I saw a thread on it somewhere but for the life of me I cannae find it. :)



#13 TYREDNGRUMPEE

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Posted 29 August 2014 - 03:52 pm

 All fingers now point to a knackered fuel pump as there is fuel in the vacuum pipe on the LHS cylinder.

 

 

 

 

Any sign of fuel in the vacuum pipe?  :yahoo:  :banana:  :yahoo:

 



#14 Beancounter

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Posted 29 August 2014 - 04:17 pm

 

 

 

I thought someone had mentioned that on my thread!  Sorry mate, poor obs on my part. :(



#15 TYREDNGRUMPEE

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Posted 29 August 2014 - 04:36 pm

 

I thought someone had mentioned that on my thread!  Sorry mate, poor obs on my part. :(

 

S'allright.

I do make a point of having a disco now when this happens, Bee Crows, more often than not, a thread will take a circular path over a week or two and my "mystic" insight will get swept unner the carpet.  :cleanup:

There's still a few jigs pending out there yet!



#16 Studley Ramrod

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Posted 29 August 2014 - 05:05 pm

It could be a faulty/worn fuel pump.  There's a vac pipe that runs from the pump to an inlet stub on the cylinder intake.  If the pump diaphragm is worn or pinholed, fuel collects in the vac pipe and then runs straight into the cylinder, flooding it.

 

Ahem !


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#17 bigmick1981

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Posted 29 August 2014 - 05:07 pm

Fuel tap gasket is fine.  All fingers now point to a knackered fuel pump as there is fuel in the vacuum pipe on the LHS cylinder.
 
ISTR that you can fit an electric fuel pump instead of the mechanical one, sure I saw a thread on it somewhere but for the life of me I cannae find it. :)

http://www.carpe-tdm...p?showtopic=201

#18 TYREDNGRUMPEE

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Posted 29 August 2014 - 05:17 pm

 

Ahem !

 

Quite so.  :blush2:

Proving my earlier assertion, if proof were needed, "that a great deal of good advice goes unheeded" in the thread process.  :banana:



#19 Beancounter

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Posted 29 August 2014 - 05:26 pm

 

Ahem !

 

:blush2: :)

 

 

Thanks mate, appreciated. :)



#20 Studley Ramrod

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Posted 29 August 2014 - 05:35 pm

To be fair, fuel isn't stuck in the pipe all the time, it seems to collect there then gets sucked into the cylinder when you fire her up. :)

 

Anyhoos, hope ya get it sorted matey. :good:


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