Fuel Issues - 2003 3.0L
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Cargo Master
Joined: Nov 2015
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From: Fort Worth, TX
Fuel Issues - 2003 3.0L
My wife's Escape was showing signs of a failing fuel pump (hard starting, wanting to stall at stoplights) so I scanned it with AE and found no codes but the "fuel pump duty cycle" PID showed 100%. I figured the pump was just worn out, and at 300k I figured it was time for a new one, so I replaced it. So far the car starts and runs fine, and fuel pressure at the rail measures 60psi with a test gauge with the engine running. When I stop the engine the pressure drops to 50psi immediately, 40psi after a few minutes, and 20psi after a few hours. I just replaced the fuel injectors 6 months ago with Motorcraft parts. Could they already be leaking that badly? Or would a faulty fuel rail damper cause this?
Also, the fuel pump duty cycle is still showing 100%. I did a voltage drop test at the pump and the power side had a drop of 0.9 volts. It seems that with a significant drop like that, the engine wouldn't be getting enough fuel and not the other way around.
Also, the fuel pump duty cycle is still showing 100%. I did a voltage drop test at the pump and the power side had a drop of 0.9 volts. It seems that with a significant drop like that, the engine wouldn't be getting enough fuel and not the other way around.
Hotshot
Joined: Jan 2004
Posts: 19,762
Likes: 1,079
From: St Louis
On an 03, fuel pump duty cycle is always 100% unless the pump is OFF (then it's 0%). It's not a variable duty cycle pump.
Most likely, you have a pressure regulator on the pump module. Did you replace the whole unit or just the pump motor?
If you had an injector problem, you would know it (hydrolock, gas in oil, black smoke on startup). The damper cannot cause your issue.
Most likely, you have a pressure regulator on the pump module. Did you replace the whole unit or just the pump motor?
If you had an injector problem, you would know it (hydrolock, gas in oil, black smoke on startup). The damper cannot cause your issue.
Senior User
Joined: Dec 2016
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I wouldn't worry about that leakdown of pressure over that time period at all. Likely it is entirely normal back drain through the pump when off. Gas is an incompressible liquid so that pressure drop represents a tiny volume of fuel draining back through the pump assembly.
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Cargo Master
Joined: Nov 2015
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From: Fort Worth, TX
I replaced the whole sender unit.
I called Delphi's tech support line. They said to bleed down the pressure to 10psi, and if it drops more than 2psi in any 5 minute period then it fails.
I also asked about the duty cycle and at first he said 100% is normal, it's "like a light switch", then after explaining my reasoning, he said the voltage should vary. I think he was caught up in the thought that the car has a fuel pressure sensor on the fuel rail, even I told him it doesn't. Then he said to check the fuel pump control module. I called Ford, gave them the VIN, and they said it doesn't have one.
After reading your replies I feel better, the wife feels better, and I"m not going to worry about it. Thanks for your input guys!
I called Delphi's tech support line. They said to bleed down the pressure to 10psi, and if it drops more than 2psi in any 5 minute period then it fails.
I also asked about the duty cycle and at first he said 100% is normal, it's "like a light switch", then after explaining my reasoning, he said the voltage should vary. I think he was caught up in the thought that the car has a fuel pressure sensor on the fuel rail, even I told him it doesn't. Then he said to check the fuel pump control module. I called Ford, gave them the VIN, and they said it doesn't have one.
After reading your replies I feel better, the wife feels better, and I"m not going to worry about it. Thanks for your input guys!
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