Fuel starvation

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davex7id
Posts: 7
Joined: Fri Mar 21, 2008 10:04 pm

Fuel starvation

Post by davex7id »

Hi,

I have a fuel starvation problem and believe I have tried just about everything to solve it, so any new ideas would be gratefully received. My NS400R periodically dies and stops, at which point, the fuel line and carbs are empty. This is easy to check as I have a transparent in line fuel filter fitted and I can see this is empty of fuel. If I wait a few seconds and kick the bike over, the fuel begins to flow again and the bike starts. To try to fix this problem, I have so far done the following:

Cleaned the carbs and checked float heights (in fact I have even tried a different set of carbs with no change)
Replaced the fuel tap with a brand new one (mine was leaking anyway)
Checked the vacuum pipe for leaks
Removed the fuel filter
Checked the vent hole in the fuel cap (I have even drilled an extra hole, to make sure!)

I think I have worked on every element of the fuel system, so if any one can suggest what to try next, I'd really appreciate it.

Thanks for any suggestions offered.

Kind regards,

Dave

Ian
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Re: Fuel starvation

Post by Ian »

Taken the fuel filter out of the tank and inspected/cleaned it?
Confirmed that the new fuel tap diaphram is working properly?

davex7id
Posts: 7
Joined: Fri Mar 21, 2008 10:04 pm

Re: Fuel starvation

Post by davex7id »

Hi Ian,

Thanks for the reply.

When I connect a fuel line from the tap into a container and kick the bike over, a healthy squirt of petrol enters the container, so I think the diaphram is fine and the fuel filter in the tank was new with the fuel tap.

Regards,

Dave

oldstrokers
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Re: Fuel starvation

Post by oldstrokers »

Dave
Have just wrestled with fuel tap related problems- the following might be worth having a look at...
Stick a vacuum on the diaphragm line ( put a pipe on the diaphragm side, suck hard, clamp it off, see if fuel continues to flow).
Run it with cap open
Run it from a container of fuel
Don't implicitly trust a new tap- depends how long it's been sitting on the shelf!
I ended up having to build a tap assembly from one new and two used taps :)
Never buy a 20,000 piece jigsaw without a picture on the box!
http://www.strokers.co.uk

Ian
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Re: Fuel starvation

Post by Ian »

oldstrokers wrote:Dave
Have just wrestled with fuel tap related problems- the following might be worth having a look at...
Stick a vacuum on the diaphragm line ( put a pipe on the diaphragm side, suck hard, clamp it off, see if fuel continues to flow).
Run it with cap open
Run it from a container of fuel
Don't implicitly trust a new tap- depends how long it's been sitting on the shelf!
I ended up having to build a tap assembly from one new and two used taps :)
I would have gone on to say something similar. A new tap could easily be 20 years old now.

oldstrokers
Posts: 55
Joined: Sat Jun 07, 2008 8:43 pm
Location: Deep in the south west
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Re: Fuel starvation

Post by oldstrokers »

Ian wrote:
oldstrokers wrote:Dave
Have just wrestled with fuel tap related problems- the following might be worth having a look at...
Stick a vacuum on the diaphragm line ( put a pipe on the diaphragm side, suck hard, clamp it off, see if fuel continues to flow).
Run it with cap open
Run it from a container of fuel
Don't implicitly trust a new tap- depends how long it's been sitting on the shelf!
I ended up having to build a tap assembly from one new and two used taps :)
I would have gone on to say something similar. A new tap could easily be 20 years old now.
That's true- mine was a "new" tap- the main seal had dried up and was shot. Had to replace it (after drilling out rivets, tapping holes etc, with an O ring rather than lipped seal) - tap now tight to turn but no leaks. The diaphragm was also stuck closed. :x
Never buy a 20,000 piece jigsaw without a picture on the box!
http://www.strokers.co.uk

davex7id
Posts: 7
Joined: Fri Mar 21, 2008 10:04 pm

Re: Fuel starvation

Post by davex7id »

Hi,

Thanks for the advice, I'll experiment with the new tap.

Regards,

Dave

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