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Discussion Starter #1
2005 Taurus with 3.0 DOHC engine.
After a lengthy time off the road I finally finished all the repairs. My first test drive ended in disaster as the engine died with what seemed to be fuel starvation. Start the engine and as you put it in gear the revs would slowly drop until it died. Started and let idle, and after a few seconds again the revs slowly dropped and it died.
I’ve owned enough carbureted cars/bikes over the years to recognize fuel starvation.
Got it towed home and hooked up the ForScan. P0171 & P0174 had set which confirmed a fuel problem. No other codes had set.
Checked for vacuum leaks and a stuck open EGR valve, but everything was fine.
Watching the data stream and it showed the fuel pressure at about 37 PSI and the fuel pump PWM signal was 29% at idle.
During my previous repairs I had changed out the fuel pressure sensor, simply because I dropped something on it and broke it. I had also put in a new fuel filter, which I checked and found to be clear, but I put a new one on anyway as it’s a messy job.
Of course it starts and runs fine now, but I can’t trust it or afford another towing charge.
My question is, what is the failure rate for the fuel pump, which I believe may be the culprit, but I’m not looking forward to dropping the tank and want to rule out any other possibilities.
 

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29% duty cycle on pump at idle is reasonable. What pressure was the fuel pressure PID reporting?

99.9% of the time, 171 / 174 are caused by vacuum leaks, NOT fuel supply issues, especially if you didnt get a P0191 code along with the 171/174 codes.
 
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Discussion Starter #3
37 PSI according to the PID, but I haven't hooked up a mechanical fuel pressure tester yet.
I've been all over the engine, EVAP and PCV system and there are no vacuum leaks.
I let the car sit overnight and it started and ran fine, which is also not indicative of vacuum leaks.
Nothing worse than an intermittent fault.
 

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Always suspect the pump modulator on these cars. Fuel pumps that are modulated last a long time. I have had three Taurus that the pump were going strong after 250k miles.
 

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A month ago I would have dismissed as skeptical what I am about to suggest. Three or four times over the last year I have had a starting problem after shut down and attempt to restart. I did not hear the fuel pump prime and it acted as if it had run out of fuel. It cranked just fine but acted as if no fuel. Similar to vapor lock in the pre fuel injected cars. Waited about 20 minutes and the car would start. No diagnostic trouble codes, fuel pump, Motorcraft brand has about 50,000 miles on it. Recently was getting a trouble code out of the power control module #1233. It was suggested that I clean the grounds like something so simple would solve my problem. I disconnected, cleaned and reattached the grounds, especially the PCM ground. Unbelievably to me my PCM trouble code was gone. I now hear the fuel pump prime loud and clear every time. I also can now listen to some AM radio stations that used to be so full of static it was unlistenable at a park I sometimes spend the lunch hour. If the fuel pump is worn and the problem it will need to be replaced. When mine was going bad had trouble codes about secondary electrical circuit. Try cleaning your grounds, much easier than dropping the tank. I was skeptical but three weeks later the DTC are gone. The fuel pump primes every time, consistent starting. If I have Automender12345 luck I have about 200,000 miles before I need to replace fuel pump.

Scott
 

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Have you checked LTFT values on both banks at both idle and with the engine under load?
 

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Discussion Starter #7
I will check the grounds, but I can hear the fuel pump prime every time. I will admit that the pump is a little on the noisy side, but I'm not sure what others would consider noisy.
As this car has cost me far more money than it's really worth and it looks like even more money now needs to be spent, I'm now leaning towards a conversion to make it hundreds of times more reliable. Convert it into a cube about a yard square, and then buy a Toyota.;)
 

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I have had 2 '03's fail pumps not all that may miles but over a 100K. I got spare module from the JY and switched it out, no fix. Pumps were bad. Not the same but I had '95 pump fail and had to have it replaced out of town, and '92 noisy replaced, and '93 Lin cont replaced due to noise under warranty. My op. Pumps are wear items but life will vary a lot. No reason the module should fail as it is in a very clean place. Grounds are another story. Ford has weak grounds by my experience. Bolting an eyelet over paint just does not get it. (ok off my soap box)
-chart-
 

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Have you ever changed the intake manifold and EGR gaskets? Mine caused my car to lost compression and tripped the oil pressure sensor...
 

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If the gas in the tank is too low, the pump will be damaged. Even a single occurrence of low gas in tank is a pump killer. I knew a Ford service manager who told me that you should never get lower than 1/4 tank. The gasoline in the tank cools the pump. Low gas lets the pump be damaged.
 
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