Intermittent Fuel Pump
 

Having problems with 2001 F150 5.4 2WD. Fuel pump went out a few weeks ago, R&R fuel pump, strainer, filter. It quit on me Saturday. Got it home and the fuel pump would only run for a second or less. Took out fuel pump relay and bypassed the 87 - 30 and it still only ran about a second or less. I believe it should run continuous with these jumpered.

I took the fuel tank out and removed fuel pump. I took the wire connector apart between the pump and the lid. Jumper the pump and it ran as long as it had current. Plugged it back into harness coming from the lid and jumped the prongs there, ran there also. This tells me the pump is working.

Took it out to pu and plugged into main harness and jumped the 87- 30 and it ran a second or less.

Why will it only run a brief second with it plugged in? It will run when you first touch the terminals and then quits. It will run everytime for a brief second as long as you remove the jumper in between trys.

Am I missing something somewhere? I did a search this morning and nothing showed up. Any insight would be greatly appreciated!

Regards, Jeff

Here is how it's supposed run.
On key to 'run' position it will only run about 1 second and stop.
At crank over the PCM will restart it full time.
The PCM supplies the ground to operate the relay.
The relay connects a fused 12 volt source through the crash sensor to the pump.
Discribe what conditons are you doing, to test it.

I pulled the relay and jumped the 87 to 30 terminals. I thought this should run full time this way?

My problem is no fuel pressure. Pump won't run when cranking.

Regards, Jeff

The pump power is a two stage affair.
I don't know the wire terminal numbers but is the failure in the PCM to relay operation or the relay to pump?.
If you jumper ground to operate the relay, does the pump run?
A this point, your on the PCM control side of the circuit.
If the relay operates, pump does not run, the circuit from the relay contacts to the pump are in trouble.
If the pump does run at his point, the PCM is not providing the ground either at prime time or cranking time.
Either a contact issue or the PCM solid state control switch is faulty.
Could even be the large PCM connector.
Voltmeter is the way to check all this out.
You can put a lamp on the pump connector and see when power get's to that point.
Seems that your pump begins to run then stops is a function of load current.
At inital connection it starts then stops as the pump pressure increases the load current.
That almost sounds like a burnt contact along the path offering to high a resistance.
The pump draws in the area of about 7 amps from it's own fused source. The PCM cannot handle that amount of continious current for a long term design on the PCM board so uses a slave relay circuit.

Ok here is where I'm at. When I turn the key to ON position I get a burp of fuel out of the line.

I have the tank out and just put a hose on the end of the tank nipple so I can see if fuel comes out.

When I go to the START position no fuel. Took the plastic cover off the relay itself and manually pushed the contacts together and it shot out a stream of fuel.

I then moved the relays aorund and they all worked where they were put so the relays are working.

You mentioned something about the "PCM solid state control switch." Could you please tell me what that is and whre it is located? If I could get the relay activated it would pump fuel.

Thank You!

Regards, Jeff

Hear is more indepth info in how the pump relay is controlled by the PCM.
At the moment the ignition switch is put to run, the PCM is powered up.
In the PCM is a timer circuit that grounds the pump relay switch circuit (in the PCM) so the pump begins to prime the fuel rails and shorten the crank time for starting.
When the timer runs down the pump stops. This time interval is about 1 to 2 seconds normally.
As the engine is cranked, the crank sensor signals the PCM that cranking is taking place.
This along with many other funtions, starts the fuel pump again full time as long as the crank is rotating by restarting the timer and keeping it in that condition.
It is designed this way as a matter of safety in case of an accident that also includes a crash sensor so the pump will not feed a fire situation.
Seems you have proven the relay to pump circuit is good.
************************************************** ************
Now to prove out the PCM ability to provide a ground to the relay.
Find the lead from the PCM to the crash sensor and relay. Hook up a meter to check for the ground when you crank the motor.
If it is not there, either the lead, the connector at the PCM has an issue or the solid state switch is faulty inside the PCM.
If the PCM, then unfortunetly the PCM would have to be replaced.
PCM replacement requires a dealer program load to the new unit, and two PATS system ignition keys to reprogram because that also changes the PATS codes and dash communications.
The only way to get around this on a temporary basis, if the PCM has the fault, is to install a manuel switch to provide a ground and run the pump.
You could wire up a small relay that would operate only when the igntion was in the run position, to provide a ground.
Just be sure you don't allow the pump to run full time when the motor is off.
Doing this loses some accident protection if the battery feed to the relay is still in tact after an accident and the igntion is still in 'run'. Hopefully the crash sensor trips to stop the pump in that event.
Good luck.

Put fuel tank back in and put a piece of paper to hold relay contacts for pump to run constantly. Pumps fuel to the rail with plenty of pressure but no start. Sprayed some gas into intake and starts and dies when the gas I sprayed runs out even with pump running constantly by holding contacts together. Don't understand this at all.

THEFT light is blinking rapidly, I have no odometer lights. Let the THEFT light flash for a couple minutes then it blinked once and paused then four times, it repeated this 3 times. I have no engine codes showing up with my hand held scanner.

Pulled the plugin from the PCM on the firewall and all wires are good with no bare spots and pins all looked clean and shiny. Battery is fully charged and is in good shape.

Looked through the search function on the blinking THEFT light but only confused me more. Will look through it some more later, brain is tired.

Right now I would whizz on a spark plug if I thought it would do any good.

Thank You for the replies!

Regards, Jeff

Jeff, you now have a PATS issue that is not allowing the PCM to start the motor..
Flash code 14 is the following.
Partial key code received, try again, or use your spare key. Allow about 2 to 3 minutes between trys for the PATS to reset.
If it does not work, it's dealer time.
You can also trigger the dash diagnostics and see a different code that will 'interpet' from a code chart, to be equal to the flash code.
A scanner used on the PCM would read a code that is different yet but tells the same thing. Only difference in all these is how and where they are read from. They all refer to the same fault.
The dash codes are called a HEC codes.
Stick with it.
Maybe the truck thinks your trying to kidnap it, hi hi.
Good luck.

No luck at all. Gonna load 'er up and haul it to the Dr. :(

Thank you so much for your help! It is greatly appreciated!!:-drink

Regards, Jeff