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jjs4348 06-30-2010 06:11 AM

Help!!! No fuel to motor
I have no gas coming from fuel pump and cannot figure out what is wrong. I changed my battery 2 weeks ago then last week my jeep wouldnt start so I pulled the fuel line under the driver door and no fuel came out when I turned the key so i bought a used pump assembly from another jeep and installed it. This worked for two days but again it will not start. I bought another used pump and installed it and still no fuel comes out. I have no codes...all fuses are good, and I swapped the relay with one of my working ones. I have no idea what is wrong. I put a voltage meter to the plug to find out if there is power and i do get some voltage but im not sure what the voltages need to be at. Any help would be greatly appreciated. I am depending on my street bike now to get me to school and it has rained on me every day so far...I need my jeep running.

ny450es 06-30-2010 07:26 AM

Re: Help!!! No fuel to motor
might be a bad pcm...when you turn the key to the start position does the engine crank?

jjs4348 06-30-2010 07:34 AM

Re: Help!!! No fuel to motor
yes the motor will crank but not start

scjeep4.7HO 06-30-2010 08:07 AM

Re: Help!!! No fuel to motor
May have a bad relay that turns on the fuel pump. Check for voltage going to the pump. You can also pull the relay and install a cotter to jumper across the pins in the relay base that sends power to the pump. If the pump turns on you know that the relay is bad.

Or the easiest way would be to just swap another relay in it's place and see what happens.

jjs4348 06-30-2010 08:59 AM

Re: Help!!! No fuel to motor
i tried that...any other ideas?

jjs4348 06-30-2010 01:04 PM

Re: Help!!! No fuel to motor
ok i just checked the voltages at the pump plug and pins 1,2, and 3 have voltage but 4 does not. This is the problem i know because it should show at least 12V when the key is turned on for about 5-10sec. Does anyone know what this wire is for? PLease help

Escape 06-30-2010 02:32 PM

Re: Help!!! No fuel to motor
Did you check the ASD Relay located under the hood.

This is what happens when you turn the key.

This is an Open Loop mode. When the fuel system is activated by the ignition switch, the following actions occur:
The PCM pre-positions the idle air control (IAC) motor.
The PCM determines atmospheric air pressure from the MAP sensor input to determine basic fuel strategy.
The PCM monitors the engine coolant temperature sensor input. The PCM modifies fuel strategy based on this
Intake manifold air temperature sensor input is monitored.
Throttle position sensor (TPS) is monitored.
The auto shutdown (ASD) relay is energized by the PCM for approximately three seconds.
The fuel pump is energized through the fuel pump relay by the PCM. The fuel pump will operate for approximately
three seconds unless the engine is operating or the starter motor is engaged.
The O2S sensor heater element is energized via the ASD relay. The O2S sensor input is not used by the PCM
to calibrate air-fuel ratio during this mode of operation.

This is an Open Loop mode. The following actions occur when the starter motor is engaged.
The PCM receives inputs from:
Battery voltage
Engine coolant temperature sensor
Crankshaft position sensor
Intake manifold air temperature sensor
Manifold absolute pressure (MAP) sensor
Throttle position sensor (TPS)
Starter motor relay
Camshaft position sensor signal
The PCM monitors the crankshaft position sensor. If the PCM does not receive a crankshaft position sensor signal
within 3 seconds of cranking the engine, it will shut down the fuel injection system.
The fuel pump is activated by the PCM through the fuel pump relay.
Voltage is applied to the fuel injectors with the ASD relay via the PCM. The PCM will then control the injection
sequence and injector pulse width by turning the ground circuit to each individual injector on and off.
The PCM determines the proper ignition timing according to input received from the crankshaft position sensor.

The wires going to your fuel pump are as follows:
1. Color = BK, Gauge 18, Ground
2. Color = BK, Gauge 20, Ground
3. Color = DB/YL, Gauge 20, Fuel level sensor
4. Color = TN/RD, Gauge 16, Fuel pump relay from integrated power module from fuel pump relay controlled by the ASD relay.

There is also the pickup strainer, fuel pressure regulator and fuel filter in the tank assembly. Did you check those also?

jjs4348 06-30-2010 03:28 PM

Re: Help!!! No fuel to motor
i swapped the asd relay with the HVAC relay since they are the same and no change... The asd fuse seems fine as well. The fuel pump works when connected to the battery. I am getting votage for three seconds but it seems to be very low voltage. It is upsetting because I can rebuild motors but cannot figure out why one wire does not have voltage. It makes no sense to me...and the stealership cannot get to my vehicle for a week. What to do besides blow the dam car up?

jjs4348 06-30-2010 03:35 PM

Re: Help!!! No fuel to motor
i checked the strainer adn filter but not the regulator

jjs4348 06-30-2010 03:36 PM

Re: Help!!! No fuel to motor
how do i check the regulator?

gc4x4 06-30-2010 03:54 PM

Re: Help!!! No fuel to motor
Maybe the alarm system has gone bad,with it thinking that the jeep is being stolen? The alarm recently went out on my friends Malibu and it kept the fuel pump from getting power, leading her to replace everything under the sun to only discover it was the alarm the whole time. Good Luck.

jjs4348 06-30-2010 04:13 PM

Re: Help!!! No fuel to motor
o geez i hope its not something that far off . I wouldnt even know where to begin checking the alarm

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