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russellbaldwin

Leak from fuel pressure release valve

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Hi

I had a fuel cavitation problem the other day - second time in 25 years!  It was a hot day, the roads were melting but I've driven it through France last year which was much hotter and I had a full tank of fuel.  And I've smelt fuel on startup, so think this was related...

I thought I'd replace the primary filter incase that was blocked.  I ran the fuel pump from cold and found a leak from the pressure release valve pipe that takes fuel to the metering unit.  I can't replicate the leak now the system is up to pressure.  The jubilee clip around the pipe is tight - and I don't want to over tighten and break into the rubber.  

Any ideas if the fix it just tightening the clip or a more complicated problem with the valve?  Sorry if this is a noddy question...

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Try a second jubilee clip with the screw tightener spaced 180 degrees from the current one. And make sure the current jubilee clip is tight.

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Hi Russel,

I do not  recommend the use of jubilee clips on this 105 psi fuel hose (and potentially more). Imagine the hose coming off the ferrule....

If your rubber hose is leaking now, this is a good moment to replace with a suitable hose, with crimped fittings and rated for this pressure/temperature.

Regards,

Waldi

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From my understanding the PRV releases the fuel what is not needed via a pipe

back to the tank or into the fuel filter what ever is routed. Also the metering unit

releases a little bit of leaking fuel back by a pipe back to the tank.

 

Both pipeworks should nowhere be under fuel pressure.

I wonder if I understood something wrong or there is something blocked in the pipework.

As at the front the leaking fule is only isolated by a "Simmering" to the oiled area I would

check what is going on there. Fuel pressure to let a rubber hose drop should not be there.

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Russel indicates the leakage is the pipe from PRv to MU, which is the high pressure side.

Cheers,

Waldi

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Thanks all.  Waldi - thanks for observation on the fixing - hadn't noticed this.  It's been like it for decades - no excuse and now I know about it I'll have to get that fixed.  Thanks for your help  

Cheers, Russell.

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7 minutes ago, Mark69 said:

Shouldn't that pipe be copper not rubber. 

Hi Mark, 

The line from PRV to MU is mainly metal, but the first and last section are rubber hose.

I always thought that a rubber hose is a hose and a metal pipe is a pipe. What is the correct terminology for both? I’m a bit confused now.

Thanks,

Dutch Waldi

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Waldi, your absolutely right with your terminology, I have a high pressure hose from pump to prv then it’s pipe  to high pressure hose attached to the mu.

Mark

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Thanks Mark.

For the foreign non English speaking members it is sometimes a bit difficult, and confusion is just around the corner.

Best regards,

Waldi

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On 7/12/2019 at 12:51 PM, Waldi said:

Hi Russel,

I do not  recommend the use of jubilee clips on this 105 psi fuel hose (and potentially more). Imagine the hose coming off the ferrule....

If your rubber hose is leaking now, this is a good moment to replace with a suitable hose, with crimped fittings and rated for this pressure/temperature.

Regards,

Waldi

I agree with Waldi only use crimped sleeves on HP hoses, in my view it is a dangerous practice to use jubilee clips for this type of application! As they often do not give a full 360 degree clamping force and have to be over tighten to seal the rubber hose, which then damages the hose.

Bruce. 

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Tube is measured by outside diameter,  whereas Pipe is measured by inside diameter.  Important to remember when ordering.   

Gardens might have a hose pipe.  Cars generally use pipes : rigid and flexible.   ie.,  rigid fuel pipe, flexible fuel pipe, pipe clips, etc.

Rubber is often generically terminology used for various sorts of plastics, silicons, and other flexible composites. 

Pipes are used in the design process because it is the internal cross section which is relevant to flow calculations, irrespective of whether it may be used for petrol, oil,  brake fluid, exhaust, screen wash or water pipes to the car's heater.   Oddly, only the radiator has a top and bottom hose . .except in a house - where the radiators have pipes  ..oh dear,  now I'm getting confused  :wacko:

:D

Edited by Bfg

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Thank you for the clarification. Now I’m lost forever:)

Think I need a drink, either from a pipe, hose or tube.

Cheers,

Waldi

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