Fuel Pump Runs after Ignition Off on Occasion - Taurus Car Club of America : Ford Taurus Forum
 3Likes
  • 1 Post By Automender12345
  • 1 Post By sheila
  • 1 Post By chartmaker
 
LinkBack Thread Tools
post #1 of 9 (permalink) Old 04-21-2019, 02:22 PM Thread Starter
Junior Member
 
hrtull's Avatar
 
Join Date: Mar 2019
Posts: 13
Rep Power: 0
 
Garage
Trader Score: 0 reviews
Fuel Pump Runs after Ignition Off on Occasion

2002 Taurus Wagon 3.0 OHV 91k miles. On occasion my fuel pump with run 30 to 40 seconds after ignition is turned off. Most of the time it runs normal. Meaning when switch is turned on pump starts with a smooth hum for a second or two and when ignition is shut off it shuts off. When pump does continue to run longer than normal the pump sounds rough as if it is going bad. I replaced the fuel pump relay and no change, it remains as a random event. OBD shows 40lbs +/- fuel pressure. Car runs fine with good gas mileage. I can only guess at the start up sequence. My guess, ignition on, relay activates pump, pressure sensor shuts pump on and off as required while engine running. If that is the correct sequence I would think pump could not run after ignition shut off. Any suggestions would be greatly appreciated, Thanks HRTULL

Time is a Bandit, it eventually steals everything.
hrtull is offline  
Sponsored Links
Advertisement
 
post #2 of 9 (permalink) Old 04-21-2019, 04:38 PM
Crazy Devoted Member
 
Join Date: Jan 2010
Location: North Canton, Ohio
Chapter: Midwest
Year: 2006
Model: Ford Taurus
Engine: 3.0L 12v Vulcan V6
Posts: 6,404
Rep Power: 63
    
Trader Score: 0 reviews
Maybe a sticking fuel pump relay. You can swap it with another relay in the power distribution box in the engine compartment.
jag1959 likes this.
Automender12345 is online now  
post #3 of 9 (permalink) Old 04-21-2019, 05:50 PM
Crazy Devoted Member
 
Join Date: May 2011
Location: NY State
Chapter: Northeast
Year: 2003
Model: Mercury Sable
Engine: 3.0L 24v Duratec V6
Posts: 9,469
Rep Power: 98
      
Garage
Trader Score: 0 reviews
Quote:
Originally Posted by hrtull View Post
2002 Taurus Wagon 3.0 OHV 91k miles. On occasion my fuel pump with run 30 to 40 seconds after ignition is turned off. Most of the time it runs normal. Meaning when switch is turned on pump starts with a smooth hum for a second or two and when ignition is shut off it shuts off. When pump does continue to run longer than normal the pump sounds rough as if it is going bad. I replaced the fuel pump relay and no change, it remains as a random event. OBD shows 40lbs +/- fuel pressure. Car runs fine with good gas mileage. I can only guess at the start up sequence. My guess, ignition on, relay activates pump, pressure sensor shuts pump on and off as required while engine running. If that is the correct sequence I would think pump could not run after ignition shut off. Any suggestions would be greatly appreciated, Thanks HRTULL
Pump module is powered by a relay and if the relay does not open, there will be power to the module. If the key is off and it is still powered up by the relay, you do not have the signal from the PCM to manage the volts for pressure management by the module. Thus you can have a over pressure. Highly like not the module at fault as it should have no power when the relay opens. The pressure is regulated by adjusting the duty cycle of the negative line to the pump motor. The positive side of the pump motor is powered by battery volts through the relay.


-chart-
Attached Thumbnails
Click image for larger version

Name:	FuelPumpMod.jpg
Views:	10
Size:	240.5 KB
ID:	208555  
chartmaker is online now  
 
post #4 of 9 (permalink) Old 04-21-2019, 10:00 PM
Crazy Devoted Member
 
Join Date: Dec 2006
Chapter: Midwest
Year: 1998
Model: Mercury Sable
Engine: 3.0L 24v Duratec V6
Posts: 22,074
Rep Power: 112
     
Trader Score: 1 reviews
^ Fwiw, he said he replaced the fuel pump relay to avail...
snosaint likes this.
sheila is offline  
post #5 of 9 (permalink) Old 04-22-2019, 06:10 AM
Crazy Devoted Member
 
Join Date: May 2011
Location: NY State
Chapter: Northeast
Year: 2003
Model: Mercury Sable
Engine: 3.0L 24v Duratec V6
Posts: 9,469
Rep Power: 98
      
Garage
Trader Score: 0 reviews
Quote:
Originally Posted by sheila View Post
^ Fwiw, he said he replaced the fuel pump relay to avail...
The only source of power is through that relay and the inertia switch. I would have someone help by turning the key off while the engine is running then I would pull the relay and see if that kills the pump. If so, the source of "run on" is the signal to the relay.


-chart-
snosaint likes this.
chartmaker is online now  
post #6 of 9 (permalink) Old 04-22-2019, 08:11 AM
Technical Advisor
 
Join Date: Feb 2007
Location: Milwaukee, WI
Chapter: Midwest
Year: 2005
Model: Ford Taurus
Engine: 3.0L 24v Duratec V6
Posts: 7,516
Rep Power: 86
     
Trader Score: 0 reviews
Possible intermittent short to ground in the pump relay coil to PCM control circuit.

05 Taurus SEL Duratec - my daily driver
04 Taurus SES Duratec - wifes car - TOTALED
06 Taurus SE Vulcan - wifes new ride
95 Taurus GL Vulcan winter car
Toy #1 - 86 Tbird 5.0 (original owner) - LOTS of mods
Toy #2 - 88 Tbird Turbo Coupe - LOTS of mods
67 Honda 450 Super Sport - completely customized
Jeff K is offline  
post #7 of 9 (permalink) Old 04-22-2019, 07:30 PM Thread Starter
Junior Member
 
hrtull's Avatar
 
Join Date: Mar 2019
Posts: 13
Rep Power: 0
 
Garage
Trader Score: 0 reviews
"I would have someone help by turning the key off while the engine is running then I would pull the relay and see if that kills the pump. If so, the source of "run on" is the signal to the relay."

I assume the signal to the relay would be controlled by the PCM which is activated by the ignition switch. Wondering if ignition switch could be an issue. So I guess that somewhere , some how a signal is being generated to fuel relay, so let the hunt begin. I will try to remove relay as suggested . Am I correct in thinking pump can only be activated thru the relay, if relay removed there is no other power source . Thanks

Time is a Bandit, it eventually steals everything.
hrtull is offline  
post #8 of 9 (permalink) Old 04-23-2019, 07:14 AM
Technical Advisor
 
Join Date: Feb 2007
Location: Milwaukee, WI
Chapter: Midwest
Year: 2005
Model: Ford Taurus
Engine: 3.0L 24v Duratec V6
Posts: 7,516
Rep Power: 86
     
Trader Score: 0 reviews
Correct..... pump is powered, via the FPDM, directly from the FP relay as shown in Charts diagram. Pump can not run with the relay out of the circuit.

05 Taurus SEL Duratec - my daily driver
04 Taurus SES Duratec - wifes car - TOTALED
06 Taurus SE Vulcan - wifes new ride
95 Taurus GL Vulcan winter car
Toy #1 - 86 Tbird 5.0 (original owner) - LOTS of mods
Toy #2 - 88 Tbird Turbo Coupe - LOTS of mods
67 Honda 450 Super Sport - completely customized
Jeff K is offline  
post #9 of 9 (permalink) Old 04-23-2019, 08:17 AM
Crazy Devoted Member
 
Join Date: Jan 2010
Location: North Canton, Ohio
Chapter: Midwest
Year: 2006
Model: Ford Taurus
Engine: 3.0L 12v Vulcan V6
Posts: 6,404
Rep Power: 63
    
Trader Score: 0 reviews
Also the PCM must have another criteria to keep the pump running other than the ignition switch. It must be something like the RPMs, cam pulse or a crank pulse since the pump is timed to shut off in a couple of seconds when just the ignition is turned to run position.
Automender12345 is online now  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Taurus Car Club of America : Ford Taurus Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
Fuel pump electrical issues! shleprock Maintenance and Repair 31 12-14-2017 06:26 AM
Is it the fuel pump? bruce miller Maintenance and Repair 32 02-09-2014 05:27 AM
Is this a fuel pump issue robertlucent Maintenance and Repair 10 12-09-2013 11:20 AM
Why won’t my car start? - Comprehensive No-Start Troubleshooting Guide behlinla Maintenance and Repair 1 01-05-2013 11:52 PM
How to Understand and Diagnose Misfires Sam Solutions to Common Problems and 'How To' Articles 0 11-12-2012 02:37 PM

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome