4.6l no spark no fuel help!
#1
4.6l no spark no fuel help!
I've gone through it as thoroughly as I can. I'm about to tear into the steering column. I have power to pcm. At least I think I do. The fuel pump kicks on when I jump it to ground through the pcm plug. I have nothing to inertia switch. My code reader will not link up. I can't find a lose wire bad fuse or relay. Is there a component that will cause this? No power to coils either. Replaced computer today. 175a fuses are good.
#2
#4
97 4.6 no spark no fuel help please
Cranks over good. I can jump the pcm plug to ground and kick the fuel pump on. I have no power to inertia switch or either coil. My code reader won't link up. I replaced or checked all the relays and fuses. It's a 97 f150 with 120000 miles. Was running fine. I left the driveway and it stalled and that was it. Replaced computer today. No loose wires yet. Both 175a fuses are good. Is there component that could short and cause this? No check engine light (anymore). No security light. Tach does not move. All voltages appear correct. Stumpd
#7
Forgive me but I don't trust what you did.
In your owner manual pages 137 to 141 are the fuse assignments.
No power to the coils and PCM would be fuse #30.
They left out fuel injectors but they are usually on the same fuse as the coils.
If your sure you have no power to the coils there would be none to the PCM.
Leave the steering column alone until you prove a need to do it.
Better stop and start all over again.
Get basic power to the system and not worry about a fuel pump that can't do anything if the motor system won't power up.
The ignition switch powers up most of the rest of the circuits through the switch and fuses.
The key lock operates a rod that operates the switch.
Check each section out until you come to a fault.
Good luck.
In your owner manual pages 137 to 141 are the fuse assignments.
No power to the coils and PCM would be fuse #30.
They left out fuel injectors but they are usually on the same fuse as the coils.
If your sure you have no power to the coils there would be none to the PCM.
Leave the steering column alone until you prove a need to do it.
Better stop and start all over again.
Get basic power to the system and not worry about a fuel pump that can't do anything if the motor system won't power up.
The ignition switch powers up most of the rest of the circuits through the switch and fuses.
The key lock operates a rod that operates the switch.
Check each section out until you come to a fault.
Good luck.
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#9
#10
Well we hope this is a start.
Listen please;
At key on, the PCM is powered up.
This grounds the lead to the fuel pump 'relay' for only a 'few' second. Is this happening?
If not, your right at the cause of the whole problem.
If yes, the circuit to the pump, though relay, and the crash sensor is open or the pump is open or pump ground is missing.
It's just common sense.
Understand the logic sequence.
What do you have?
Good luck.
Listen please;
At key on, the PCM is powered up.
This grounds the lead to the fuel pump 'relay' for only a 'few' second. Is this happening?
If not, your right at the cause of the whole problem.
If yes, the circuit to the pump, though relay, and the crash sensor is open or the pump is open or pump ground is missing.
It's just common sense.
Understand the logic sequence.
What do you have?
Good luck.
#11
No the fuel pump does not kick on. There is power to one terminal at code reader but will not link up. There is power to all fuses. I understand that the pcm grounds the fuel pump ckt to kick on and it's not. I swapped the com for a used one i don't think they both would be bad. I jumped the fuel pump port on the cpm plug to ground and it kicked on. I still am not seeing what I am missing
#12
For get the code reader issue for the moment.,. It won't tell you anything useful.
If the PCM is not powering up it cannot connect to the Reader through the dedicated Bus.
.
What your indicating is the PCM is not powering up or is faulty.
.
Why; the PCM, upon powering up, applies a Ground to the pump relay.
This relay 'has' to pass separate fused 12 volt supply to the pump circuit.
Follow the Logic.
If you can run the pump through the circuit, it's good. Don't go back to it again.
The reader/Scanner will not have any useful info at this point until it connects to the PCM and displays any 'other' faults.
Please remember that the PCM cannot tell you anything about main power if it cannot operate by it's self.
You have to be cognitive of this as a diagnostic and logic 'observation'.
Good luck.
If the PCM is not powering up it cannot connect to the Reader through the dedicated Bus.
.
What your indicating is the PCM is not powering up or is faulty.
.
Why; the PCM, upon powering up, applies a Ground to the pump relay.
This relay 'has' to pass separate fused 12 volt supply to the pump circuit.
Follow the Logic.
If you can run the pump through the circuit, it's good. Don't go back to it again.
The reader/Scanner will not have any useful info at this point until it connects to the PCM and displays any 'other' faults.
Please remember that the PCM cannot tell you anything about main power if it cannot operate by it's self.
You have to be cognitive of this as a diagnostic and logic 'observation'.
Good luck.
#13