dawsieboy84

RAV 4.2 Air in fuel system!

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Afternoon all, got an old 4.2 d4d rav4 and have come to the conclusion I have an air leak in the fuel system. Power loss and hesitation despite having the SCV changed. 

The primer on the fuel filter always needs re-doing and you can hear an audible squelch as you plunge! aftwe a few days it needs doing again?

Any suggestions on where to look and what to check?

It was suggested to me the intank pump filament may be blocked, I cannot hear the pump buzzing as I have on other cars when the ignition is turned on? should I?

 

Thanks in advance!

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There is no pump in the tank fuel is sucked through from the High pressure pump this is aided by the fuel primer holding the fuel up in the fuel filter, as you say you are having to prime the filter all the time it suggests you have an air leak, look for a fuel leak if you find one fix it if there are no external leaks then the diaphragm in the fuel primer has failed and it is allowing the fuel to drain back slowly to the fuel tank ( not unheard of on a 4.2 )

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This used to be a problem on the older Peugot/Citroen diesel engines, where the injection pump had to suck the fuel direct from the tank.  The suggested method of tracing the suspect joint was to smear the joints in grease, though I'm not sure how easy this was in practice.  Have you disturbed/remade any joint in the fuel line recently?

Is there a fuel filter in the tank?  if so, it might by now be coated in gelatinous gunge, making it difficult for the pump to suck the fuel through.  I assume you have some rubber hose in the fuel line, in which case does it show signs of hardening/cracking?  What's the condition of the fuel primer? 

As Devon Aygo says, any air drawn into the system will allow fuel to run back to the tank.  I'd concentrate on the higher parts of the fuel system first.  Another thought, not so obvious, but there may well be an "o" ring/seal where the fuel line connects into the pump.  Check the easy bits first 😊

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VVT is petrol.

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10 hours ago, dawsieboy84 said:

No they don't if you look carefully at your two examples the Avensis diesel one whilst similar is hollow as there is no lift pump just fuel pick up/returns and the level sender the Rav petrol one is more substantial as it contains a pump

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OK so what I thought was the little mesh filter being blocked, only on petrol so it now appears I was wrong!

So does anyone know any step by step for checking for fuel/air leaks? Is there a schematic for the fuel system anywhere?

This is this amazing cars only problem, and I really want to fix it! Our RAV4 is like an old Nan to us we want to keep looking after lol

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