Starting could be Fuel

Tiny
TOPDAD1947
  • MEMBER
  • 1996 TOYOTA AVALON
  • 3.0L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 174,000 MILES
The gas gauge stopped working. So I decided to replace the sending unit in the tank and also replace the fuel pump because It is all one piece. Which I did and also replaced the in line fuel filter no problems. I went to start car it starts but only runs for maybe sixty seconds. Now keep in mind this car ran perfectly before these repairs. I checked all the fuses and relays all good. Removed return line to fuel pressure regulator and found fuel pumping straight Through. If that is the return line why should that much fuel be returning to the tank? Is that normal? Otherwise I am stuck on this one. Need Help.
Monday, July 4th, 2016 AT 12:53 PM

13 Replies

Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
The fuel pump works at a very high pressure, much higher than required for engine operations. The function of the pressure regulator is to keep the fuel pressure within the required range and if you see a lot of fuel returning, it is normal. However you need to check if the pressure regulator is keeping the correct fuel pressure within the system.

Check the electrical connector. If it is not fully plugged in or there is some looseness in the contact between the pins, the circuit can fail due to high resistance when the contact heats up.

Are you able to restart easily when engine stalled?
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Monday, July 4th, 2016 AT 3:34 PM
Tiny
TOPDAD1947
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To answer your question about restart yes it does. But like I said will only run For sixty seconds or less. Also hoping this might help. When I spray starting fluid directly into throttle body it will keep running. So I figure it is a fuel problem. Your thoughts on what it could be. Thanks Tom.
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Monday, July 4th, 2016 AT 5:04 PM
Tiny
KHLOW2008
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If starting fluid keeps the engine running, that would mean a fuel fault.
Could be due to low or excessive fuel pressure. Remove a spark plug and note its condition. If it is sooty, that would mean excessive pressure as it is running too rich which would cause the eigine to stall after some running.

Did you check for trouble codes? Could be the injectors are not firing due to erratic signal from the cam sensors.
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Tuesday, July 5th, 2016 AT 7:04 AM
Tiny
TOPDAD1947
  • MEMBER
  • 35 POSTS
Check engine light is not on. Plugs are fine. Dry and clean. I Was told that there is a constant on relay that might be the problem. But I do not know Its location. I was told that once the engine starts this relay keeps current going to the fuel pump and engine components. Your thoughts on this. Thanks Tom.
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Tuesday, July 5th, 2016 AT 12:32 PM
Tiny
KHLOW2008
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  • 41,814 POSTS
Circuit opening relay works the fuel pump and is located behind right kick panel.

The fuel pump should be whirring while it is working. Get a helper to listen to the fuel pump while you start the engine and if it fails before the engine stalls, then you need to check the wiring circuit.

At fuel pump wireharness there is a Blue/Black wire. It is the power supply for the fuel pump. Attach a 12 v battery voltage to it and start engine. If engine keeps running, then the fault is from relay.
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+1
Wednesday, July 6th, 2016 AT 8:25 PM
Tiny
TOPDAD1947
  • MEMBER
  • 35 POSTS
Thanks That Sounds Like a Plan! Will Do Tomorrow! Wish Me Luck :) Tom.
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Wednesday, July 6th, 2016 AT 10:01 PM
Tiny
KHLOW2008
  • MECHANIC
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Good luck :)
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Thursday, July 7th, 2016 AT 9:41 PM
Tiny
TOPDAD1947
  • MEMBER
  • 35 POSTS
OK I Did What You Suggested and The Test Light Stays On Even When Engine Stops! Could It Be The Fuel Pressure Regulator? If It Stops Fuel To Fuel Rail After Start? Because When I Removed The Return Line And Cranked The Motor There Was A lot Of Fuel Going Back To The Tank? Otherwise I'am Still Stumped! Thanks Tom.
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Sunday, July 10th, 2016 AT 12:06 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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This sounds like the fuel pump is defective or a line is kinked at the tank.
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Monday, July 11th, 2016 AT 4:28 PM
Tiny
TOPDAD1947
  • MEMBER
  • 35 POSTS
OK Will Check Fuel Pump Tomorrow and Remove And Replace! If That Does Not Solve My Problem What Else Could It Be? Is It Possible That The Fuel Pressure Regulator is bad? Completely Open And Returning Fuel To Tank? Instead Of Doing It's Job? Thanks Again Tom.
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Monday, July 11th, 2016 AT 9:01 PM
Tiny
KEN L
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Yes it could be the regulator, here is a test you can do to see if it helps.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Let me know what happens

Best, Ken

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Tuesday, July 12th, 2016 AT 8:49 PM
Tiny
TOPDAD1947
  • MEMBER
  • 35 POSTS
Well Ken! I Did What You Suggested! And Replaced Both Cam And Crank Sensors! GUESS WHAT? YEP STILL HAVE THE SAME PROBLEM! After Another $180.00 Dollars And An Hour And A Half Of Labor! NOT THE OUTCOME I EXPECTED! KEN >:(
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Monday, September 26th, 2016 AT 6:03 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Did you check the fuel pressure? I said nothing about cam and crank sensors.
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Monday, September 26th, 2016 AT 8:05 PM

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