Fuel injection question

Tiny
MOTORGUY007
  • MEMBER
  • DODGE DAKOTA
My 1989 Dodge Dakota, 3.9L V-6, 5 sp manual, 230,000 miles will crank but not start. I can pressure up the fuel injection system by running the fuel pump manually and then it starts. Fuel pump (with intank filter) has been replaced, New Fuel lines, and Fuel Filter, Could the Pressure regulator be causing the fuel not to get to the injuctor?
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Wednesday, February 21st, 2007 AT 8:07 AM

12 Replies

Tiny
JACK42
  • MEMBER
Check the fuel pump relay.
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Wednesday, February 21st, 2007 AT 8:09 AM
Tiny
MOTORGUY007
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Sorry, I missed telling you, the relay was changed as one of the first things, it shows energized at the pump for about a second and then kicks out.I have read that this is normal.
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Wednesday, February 21st, 2007 AT 8:12 AM
Tiny
JACK42
  • MEMBER
Could be the ignition switch? Check your manual wiring diagram to see where else the power to the pump comes from.
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Wednesday, February 21st, 2007 AT 8:15 AM
Tiny
MOTORGUY007
  • MEMBER
According to the diagram I have it shows a green wire with a black stripe powered from the auto shutdown relay directly to the fuel pump. The wire appears to check fine. I hooked a test light up to the wiring at the tank, ignition on, lights for about a second and shuts off. Click heard/felt at the relay.
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Wednesday, February 21st, 2007 AT 8:21 AM
Tiny
JACK42
  • MEMBER
Auto shut down relay been replaced? Might seem ok but when a larger draw is pulled on it, could be weak
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Wednesday, February 21st, 2007 AT 8:22 AM
Tiny
MOTORGUY007
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Yes, new from crysler, Should it stay energized longer than a second or two if the engine is not started?
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Wednesday, February 21st, 2007 AT 8:25 AM
Tiny
JACK42
  • MEMBER
No, they turn off after a few seconds. Does the PCM have any power connection to the pump? Dodge was great for having the PCM control things it didnt need to
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Wednesday, February 21st, 2007 AT 8:36 AM
Tiny
MOTORGUY007
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Not that I am aware of. Does the Fuel pump for those have a check valve in it to keep the fuel system pressurized? I did read in my manual about a fuel pressure regulator on the back of the injector, could this be letting the fuel run back to the tank and the 1-2 seconds run time when the key is turned on not be enough to get the fuel back to the injector? The computer is not storing any trouble codes that should be causing a no start situation. It typically shows a 12 Battery disconnected, 34 No speed sensor signal.
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Wednesday, February 21st, 2007 AT 8:46 AM
Tiny
RASMATAZ
  • MEMBER
Jack mentioned the ASD relay-that thing too-powers up the coil-suggest you look for spark too.

Note: The PCM controls the ASD relay

HTH-Good Luck!
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Wednesday, February 21st, 2007 AT 2:31 PM
Tiny
MOTORGUY007
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Got plenty of good hot blue spark, When I run 12V straight to the pump for a few seconds (to pressure up the system) it will start and run perfectly. After it sets for a few hours it will start if I re-pressurize the system.
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Wednesday, February 21st, 2007 AT 2:36 PM
Tiny
RASMATAZ
  • MEMBER
You begining to make me think! Pump-okay lets check the pressure regulator and a check valve at the pump
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Wednesday, February 21st, 2007 AT 2:45 PM
Tiny
MOTORGUY007
  • MEMBER
I have not located a check valve anywhere in line (at least from the pump, to the outside of the tank, Is there a check valve located in the pressure regulator? According to my book it is on the back of the injector possibly in the fuel inlet? I really appreciate the time you have taken. This one is driving me nuts!
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Wednesday, February 21st, 2007 AT 2:50 PM

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