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Discussion Starter #1
Hi all, for a number of years now I’ve been trying to solve a problem with my 2003 2.5l petrol T4 stalling in really hot weather and have ruled out most of the common causes: spark and injector pulse are ok (coil, hall sensor, crank angle sensor ok), replaced fuel pump relay, fuel pump wiring ok, replaced fuel pump, fuel filter replaced regularly.

I’m now convinced it’s a fuel delivery problem – recently discovered that just before the engine stalls, current to the fuel pump suddenly drops from around 5.5 to 1 amp, fuel pressure drops from around 35 psi to < 5 psi, and the fuel pump rpm audibly increases as the amperage and pressure drops. My theory is that the drop in amperage, increase in pump rpm and drop in pressure means that the pump is no longer under load, indicative that it’s running dry, caused by hot fuel vaporising and cavitation occurring in the fuel pump.

Just wondering if anyone has seen this kind of problem with the fuel pump in T4s, or have alternate ideas on what might be happening.

Thanks, Aaron.
 

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Yes, fuel filter has been replaced. Not sure what to look for in terms of leaks, do you mean air leaking into the intake side of the fuel pump? The pump's intake aperture sits directly in fuel in the fuel tank so not obvious how to test or whether an air leak could occur at this point. Doesn't seem to be any leaks in the line from fuel pump to fuel rail - pressure measured just before the fuel rail remains at a reasonable level after turning the engine off and there's no visible leaks or petrol smell.

Thanks heaps for the advice, much appreciated. Aaron.
 

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Yes, fuel filter has been replaced. Not sure what to look for in terms of leaks, do you mean air leaking into the intake side of the fuel pump? The pump's intake aperture sits directly in fuel in the fuel tank so not obvious how to test or whether an air leak could occur at this point. Doesn't seem to be any leaks in the line from fuel pump to fuel rail - pressure measured just before the fuel rail remains at a reasonable level after turning the engine off and there's no visible leaks or petrol smell.

Thanks heaps for the advice, much appreciated. Aaron.
Air leaking into the system on the suction side ie before the pump. I've had the problem whereby the connectors on the top of the fuel filter weren't pushed in fully (they click) and it was allowing air to be drawn in. Rough idle and stalling. Check the filter housing first.
 
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