Fuel not reaching my carbs

16-05-2015, 09:32 PM

Hello
1998 600cc monster feul issues.
fuel not reaching the carb. have removed the pipe to the carb and blown down it and have heard bubbling noise from tank, can't suck fuel from it. so therfore for it is not a blocked pipe, (which i have replaced most of as this is a revamp job - 4 years in the prossess off)

so that is question 1

to make sure the engine was OK i feed the pipe to the carb with fuel with a makeshift pretend tank and bingo it sprang into life - happy days

But

when i kept filling my pretend tank i think once the float chambers where full it just dripped from what i imagineis an overflow - does this mean the floats aint floating?

So that is question 2

Question 3:

Are question 1 and 2 linked

16-05-2015, 10:06 PM

Re-read your post. Can you suck fuel when the fuel filler cap is open?

utopia · 17-05-2015, 01:59 AM

Is the fuel tap on this bike the manual or the vacuum/diaphragm type ?
If it has the vacuum operated tap then no fuel will flow until the engine is turning (on the starter) which then creates the vacuum to open the tap.
I haven't actually seen the innards of the tap, but I presume there's a diaphragm in there and, if there is still no petrol flow even when a vacuum is applied, then this may have split or perished due to the bike being unused for 4yrs.

The carbs sound like either the float ain't floating as you say or, more likely perhaps, the float valve itself is faulty.
This could again perhaps be due to the rubber tip on the float valve being perished through being dry for 4yrs, though this is by no means the only possible cause.

So while they are two distinct problems, there could be a link in their origin......... or not.

17-05-2015, 01:30 PM

It is a vacuum/diaphragm type. It doesn't work/produce fuel with the motor turning on the starter, so this could be the issue.

Question: the fuel goes through a fuel cock - what does the fuel cock do?

Carbs need closer inspection, i did replace the jets but failed (schoolboy error) in replacing the rubber tip or checking that the floats float. - note to self - do not do again

Looking on the positive side, it seems lucky that the fuel pump wasn't workong otherwise the contents of the tank would be sitting on my drive.

@wildfire - fuel didn't flow with the cap open.

17-05-2015, 02:29 PM

Is the fuel cock fully open?
I once shut mine off when doing some work on the bike and then spent half an hour figuring why it would not start!

17-05-2015, 02:34 PM

Quote:

Originally Posted by Nick Peace

It is a vacuum/diaphragm type. It doesn't work/produce fuel with the motor turning on the starter, so this could be the issue.

Question: the fuel goes through a fuel cock - what does the fuel cock do?

Carbs need closer inspection, i did replace the jets but failed (schoolboy error) in replacing the rubber tip or checking that the floats float. - note to self - do not do again

Looking on the positive side, it seems lucky that the fuel pump wasn't workong otherwise the contents of the tank would be sitting on my drive.

@wildfire - fuel didn't flow with the cap open.

the fuel cock switches the fuel on and off ie. engine stopped fuel is switched off, engine turning/running , fuel is switched on.
After you had it running on the remote temporary fuel tank, did you try to start it when you reconnected the main tank?

Dennis menace · 18-05-2015, 11:53 AM

The vac pump relies on the 'vacuum' (drop in pressure) created by the pipe connected to the inlet manifold. Make sure that pipe is clear and sealed. I had a problem where the vent pipe to the tank was blocked and used an air line to blow it out from the top of the tank inside where the filler cap sits. One hole is the overflow/spill return, the other is the air vent. Does fuel flow to the pump under gravity?. That is, if you pull off the fuel pipe from the bottom of the pump does fuel flow with the fuel tap open? it is not easy to get to that pipe unless you unbolt the pump from the frame. Does the pump 'click' when you turn the engine over (you may 'feel it more than hear it).

utopia · 18-05-2015, 12:36 PM

And, just for clarification, I think what Dookbob is getting at is that the float bowls do take quite a while to refill via the pump if the carbs are empty from the start.
Sometimes its necessary to crank the motor repeatedly before the float bowls are properly full.
.....your gravity fed temporary system should overcome this though (as long as the makeshift "tank" is placed high enough to fill the float bowls under gravity alone.
.....though obviously, the fuel tap will still need to be confirmed as definitely being open, or else bypassed entirely.
So ....if it starts ok on the std fuel feed after having previously started on the temp tank, then the problem was merely the float bowls not having had time to fill completely.

I guess it wouldn't hurt to make sure that the fuel filter isn't blocked too.

22-05-2015, 01:56 PM

I turned the engine over with the fuel pipe disconnected and it didn't flow,

I couldn't hear/feel the pump tick - but wasn't aware it did, so wasn't really hearing for it

I will be taking it back of again this weekend to make sure all pipes & fuel filter are clear. Also taking off the float bowls to see what's up there! Lucky it's a bank holiday

22-05-2015, 07:17 PM

disconnect the pipe from the pet cock outlet, and turn it over on the starter, that will verify the pet cock is either OK or Kaput.

23-05-2015, 10:45 AM

thanks Dookbob - that's a good starting point. Did I see a post from you a while back about fuel pump innerds?

Did that work out OK?

http://www.ukmonster.co.uk/monster/s...fuel+pump+kits

04-06-2015, 09:17 PM

My Monster 600 was pretty much the same as I bought it as a non-runner. It turned out to be the fuel pipe from the tank outlet to the filter under the tank was slightly kinked preventing the fuel from flowing (as well as the carb bowls full of 'treacle' and what looked like algae). now the fuel flows as it should and the bike now runs. MOT time next once I've inspected/replaced the cam belts............. Good luck!

16-05-2015, 09:32 PM	#1
Nick Peace Guest Posts: n/a	Fuel not reaching my carbs Hello 1998 600cc monster feul issues. fuel not reaching the carb. have removed the pipe to the carb and blown down it and have heard bubbling noise from tank, can't suck fuel from it. so therfore for it is not a blocked pipe, (which i have replaced most of as this is a revamp job - 4 years in the prossess off) so that is question 1 to make sure the engine was OK i feed the pipe to the carb with fuel with a makeshift pretend tank and bingo it sprang into life - happy days But when i kept filling my pretend tank i think once the float chambers where full it just dripped from what i imagineis an overflow - does this mean the floats aint floating? So that is question 2 Question 3: Are question 1 and 2 linked Last edited by Nick Peace; 16-05-2015 at 09:40 PM.. Reason: drunk

17-05-2015, 01:30 PM	#4
Nick Peace Guest Posts: n/a	It is a vacuum/diaphragm type. It doesn't work/produce fuel with the motor turning on the starter, so this could be the issue. Question: the fuel goes through a fuel cock - what does the fuel cock do? Carbs need closer inspection, i did replace the jets but failed (schoolboy error) in replacing the rubber tip or checking that the floats float. - note to self - do not do again Looking on the positive side, it seems lucky that the fuel pump wasn't workong otherwise the contents of the tank would be sitting on my drive. @wildfire - fuel didn't flow with the cap open. Last edited by Nick Peace; 17-05-2015 at 01:44 PM..

16-05-2015, 10:06 PM	#2
Wildfire Guest Posts: n/a	Re-read your post. Can you suck fuel when the fuel filler cap is open?

17-05-2015, 01:59 AM	#3
utopia No turn left unstoned Join Date: Jun 2010 Location: leicester Bike: M750 Posts: 4,546	Is the fuel tap on this bike the manual or the vacuum/diaphragm type ? If it has the vacuum operated tap then no fuel will flow until the engine is turning (on the starter) which then creates the vacuum to open the tap. I haven't actually seen the innards of the tap, but I presume there's a diaphragm in there and, if there is still no petrol flow even when a vacuum is applied, then this may have split or perished due to the bike being unused for 4yrs. The carbs sound like either the float ain't floating as you say or, more likely perhaps, the float valve itself is faulty. This could again perhaps be due to the rubber tip on the float valve being perished through being dry for 4yrs, though this is by no means the only possible cause. So while they are two distinct problems, there could be a link in their origin......... or not.

17-05-2015, 02:29 PM	#5
DrD Guest Posts: n/a	Is the fuel cock fully open? I once shut mine off when doing some work on the bike and then spent half an hour figuring why it would not start!

18-05-2015, 11:53 AM	#7
Dennis menace Registered User Join Date: Nov 2013 Location: Farnsfield Bike: Other Ducati Posts: 300	The vac pump relies on the 'vacuum' (drop in pressure) created by the pipe connected to the inlet manifold. Make sure that pipe is clear and sealed. I had a problem where the vent pipe to the tank was blocked and used an air line to blow it out from the top of the tank inside where the filler cap sits. One hole is the overflow/spill return, the other is the air vent. Does fuel flow to the pump under gravity?. That is, if you pull off the fuel pipe from the bottom of the pump does fuel flow with the fuel tap open? it is not easy to get to that pipe unless you unbolt the pump from the frame. Does the pump 'click' when you turn the engine over (you may 'feel it more than hear it).

18-05-2015, 12:36 PM	#8
utopia No turn left unstoned Join Date: Jun 2010 Location: leicester Bike: M750 Posts: 4,546	And, just for clarification, I think what Dookbob is getting at is that the float bowls do take quite a while to refill via the pump if the carbs are empty from the start. Sometimes its necessary to crank the motor repeatedly before the float bowls are properly full. .....your gravity fed temporary system should overcome this though (as long as the makeshift "tank" is placed high enough to fill the float bowls under gravity alone. .....though obviously, the fuel tap will still need to be confirmed as definitely being open, or else bypassed entirely. So ....if it starts ok on the std fuel feed after having previously started on the temp tank, then the problem was merely the float bowls not having had time to fill completely. I guess it wouldn't hurt to make sure that the fuel filter isn't blocked too.

22-05-2015, 01:56 PM	#9
Nick Peace Guest Posts: n/a	I turned the engine over with the fuel pipe disconnected and it didn't flow, I couldn't hear/feel the pump tick - but wasn't aware it did, so wasn't really hearing for it I will be taking it back of again this weekend to make sure all pipes & fuel filter are clear. Also taking off the float bowls to see what's up there! Lucky it's a bank holiday

22-05-2015, 07:17 PM	#10
Dookbob Guest Posts: n/a	disconnect the pipe from the pet cock outlet, and turn it over on the starter, that will verify the pet cock is either OK or Kaput.

23-05-2015, 10:45 AM	#11
Nick Peace Guest Posts: n/a	thanks Dookbob - that's a good starting point. Did I see a post from you a while back about fuel pump innerds? Did that work out OK? http://www.ukmonster.co.uk/monster/s...fuel+pump+kits

04-06-2015, 09:17 PM	#12
Capstandriver Guest Posts: n/a	My Monster 600 was pretty much the same as I bought it as a non-runner. It turned out to be the fuel pipe from the tank outlet to the filter under the tank was slightly kinked preventing the fuel from flowing (as well as the carb bowls full of 'treacle' and what looked like algae). now the fuel flows as it should and the bike now runs. MOT time next once I've inspected/replaced the cam belts............. Good luck!