This 944S2 is U.S. spec and has around 150K miles on the odo.

Lots of fuel injection related parts replaced (plugs, AFM, FPR, damper, ISV, fuel filter, hoses, vacuum Y-connections, O2 sensor, etc.) but the fuel pump itself has never been changed out.

Symptoms: After an hour or so on the highway, as soon as I exit onto twisted roads and start shifting gears, the engine is very weak and begins to die out...The car then refuses to accelerate past 20 mph.

I'm suspecting the fuel pump, but don't know exactly what the symptoms are.

TIA

 

Everytime I have heard one going out it whines pretty loudly. Start your car and walk around the back, see if you can hear it.

 

That's just what I've always thought. However, this pump doesn't make any strange noise at all. I wonder if it could still be failing and not be loud?

Thanks for helping me out.

 

The pressure and volume of fuel delivered to the engine can decrease with age. The pump runs 'normally' but when the engine is under load under fuel supply doesn't meet demand.
Usually one measures the pressure and volume/time at the fuel rail.

 

The only fuel pump failure I have had: it seized up dead with no warning going down the front straight at Road America, at about 120 mph. Car shut off immediately and did not restart.

As mentioned above, checking your fuel pressure should indicate if you have low pressure/weak fuel pump.

 

The pump flows on voltage, maybe you have a lose connection and when you get some G's going the connection becomes worse, maybe the wire rubs on something, and the pump flows less... ? Just a guess.

 

In the haynes manual there is a check to see how it is doing. You unscrew the bolt on the front of the fuel rail, connect a hose that goes to a bucket or clear jug. Measure the amount in a certain time.

 

Not a direct answer to your question... you might want to check the DME relay and the suction filter inside the fuel tank. Check Clark's Garage for more details.

I just replaced my fuel pump over the weekend - it turned out the DME relay went bad. It was easy enough to take the fuel pump out and check. Wish I have done that before I bought the used one. So I now have a spare.