Fuel Pump Replaced and it still doesn't start

[rangerrick747]

2003 Ford Ranger 2.3L 4-Cyclinder, 95K miles.

Truck went dead. Engine turns over, but doesn't start. Plugs were found to have spark and the engine would run briefly if fuel was run through the throttle body.

No check engine light. Used code reader anyways and got no codes.

Thought it might be fuel related. Got a gauge on the shrader valve and found low presure (5-10PSI). Replaced Fuel pump and fuel filter, Pressure now eads 60PSI. Still won't start. We briefly bypassed the inertia switch by directly connecting the pump to the battery and the pump appears to run fine.

Replaced battery. Replaced air bypass sensor. Still no start.
Checked relays and fuses. Everything appears ok.

Checked inertia switch. Switch was ok, but reset it anyways. Checked voltage at inertia switch connectors, got 12V briefly with KOEO, but quickly went down to 6.8V thereafter. Checked continuity through inertia switch and it checked out.

Is the 6.8V reading at the inertia switch connector a concern or is that normal? Are we getting the needed voltage needed to the pump?

Maybe the PCM has bad, but how do you test it?

We also speculated the PCM may not be operating the Fuel injectors correctly. We did check voltage at the injector connectors with KOEO and found they were getting 12V.

Help needed and appreciated

 

[RonD]

Computer turns on fuel pump Relay for 2 seconds when key is turned on, it won't come on again until engine starts or you turn key off then on again.
Yes the 6-7volts is normal with key on after pump goes off, the computer monitors the voltage going to the fuel pump, that 6-7volts is coming from the computer's monitor circuit.
60psi pressure is correct, 65-70 is spec while running

All fuel injectors get 12volts when key is on, each injector has it's own Ground wire run back to the computer, computer Grounds that wire to open the injector in time with it's intake valve.

2003 Ranger will have PATS(passive anti-theft system) this system disables fuel injectors if incorrect or bad PATS key is used.
Do you have a 2nd key to try?

If you add fuel will it still start?

 

[rangerrick747]

RonD,

Thanks for your help.

We tried both of the keys that we have with the truck, but neither did the trick.

We also added more another gallon of gas. It had about 3/8 of a tank when we replaced the fuel pump. Still didn't start.

We're kind of stuck.

Any additional ideas or help are greatly appreciated.

rr

 

[Metalcrack]

Throw in some starting fluid?

Sent from my DROID RAZR using Tapatalk

 

[RonD]

Yes ^^, I meant did you add fuel to the intake manifold.
I.E. remove intake air tube open throttle and pour a little gas in or spray some starting fluid in, then try to start.
If it fires up then dies then you are correct fuel delivery is the problem.
If it doesn't fire up then you have a spark issue now.

 

[rangerrick747]

Thanks for the responses.

Yes we did the add fuel to the throttle body trick and the truck started right up for a few seconds.

We think its either the following.

No signal to fuel injectors to well, start injecting. We've speculated that this could be caused by :

A sensor going bad telling the PCM not to operate the injectors properly.
A bad PCM

The previous post of the PATS system tripping the system was also intriguing, but the car does start when you add fuel directly into the throttle body.


The other option is the new fuel pump is bad. This I'm struggling to believe as the pump sounds like its priming at start up and we have good pressure at the schrader valve (60PSI).

Thanks for your help. What started out as an opportunity for my son and I to learn about the inner workings of his truck has turned into a personal nightmare..

rr

 

[RonD]

PATS disables Fuel injectors, and on some models the starter motor as well, but it doesn't disable spark.


If you have fuel pressure above 55psi then new pump is fine.

Computer gets spark and injector timing from the CKP(crank position) sensor located on/behind the crank pulley.
If it had a problem there would be no spark or fuel injectors.
There is also a CPS(cam position sensor), it allows better sequential fuel injection timing, if it fails or gives wrong info your MPG would go down but engine would still start and run.

Since you can add fuel manually and engine starts and you have fuel pressure at the injectors then for sure injectors are not opening.

The fuel injectors all get 12volts on 1 wire when key is on, the Red wire, it is just daisy chained from one injector to the next.
The other colored wire, different color for each injector, is the Ground wire, computer controls the Ground to open and close the injectors.
You can test if an injector has 12volts, this 12v is a fused circuit but I think computer is powered by same fuse so.......you wouldn't have spark if fuse was blown, but I could be wrong, don't have a 2003 duratec engine to look at

The ground is harder to test, most use a Noid Light, these plug into the injector plug and injector, you then crank the engine and see if it flashes, flashing means computer is grounding and ungrounding that injector.
You can try a test light but it can be hard to see.

 

[rangerrick747]

We pulled a connector off the fuel injector and tested the voltage on the red wire. It read 12V. Didn't test the ground.

I'll look to see about getting the tester you've described.

thanks for the help. greatly appreciated.

rr

 

[RonD]

You can usually rent Noid Light sets, not sure if auto parts stores still "loan" them.
They only cost $20-$40, but how often would you use them...........

 

[Metalcrack]

Noid light was 8.99 at Auto zone. Works on blowers blowers tiller...... must have IMHO. RonD its starting to sound eerily similar to the TPS issue I had.

RangerRick, If you have spark on all cylinders(even one) the crank sensor is good. I would check the voltage from the TPS to the PCM.

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[RonD]

Ah yes, I forgot about that one Metalcrack, TPS voltage above 4.5volts = SHUT OFF INJECTORs
Good catch

Unplug your TPS sensor and try to start engine, you will get a CEL(check engine light), but if it starts problem is in the TPS or its wires

 

[rangerrick747]

Thanks to metalcrack and RonD for the responses.

Went around to a number of different autoparts stores (autozone, oreilly, napa) and couldn't get my hands on a Noid light. Ordered one. Waiting to receive.

In the meantime, I tried to rig up a homemaid version using a small 12v auto light which I wired into the injector connector. It failed to light up. I believe its supposed to blink if the ground is working properly.

I also checked on the TPS Sensor. Using a t-pin I checked the voltage, found the reference (grey-white) and it read 4.99V. Found the hot voltage and it read 0.85V with the throttle closed and 4.55V when the throttle was open.

We took the connector off and tried to start it. no luck. The check engine light did not remain on while we cranked the motor.

still lost but trying....

rr

 

[RonD]

TPS voltage is correct
Just FYI all fuel injection computers have a "Clear Flooded Engine" routine.
Turn key on
Press gas pedal down to the floor, and hold it down(TPS sends computer 4.5v or higher)
You are now in "Clear Flooded Engine" mode
Computer will shut off fuel injectors until foot is removed from gas pedal
So if you crank the engine it will not start, no fuel

This is what happened to metalcrack's truck, TPS failed and was sending computer above 4.5volts all the time...............so no fuel injectors

Either a PATS issue or Computer issue.
If you have 2 previously working PATS keys
Put one key in and turn key to RUN and leave it in for 5 seconds, turn it off
Put in the other key and do the same, turn it off
Put back in the first key turn it on wait 5 seconds then try to start engine

Won't work with 1 key

 

[rangerrick747]

Thanks for the info.

Tried the two key procedure. Twice. No luck.

Which leaves the PCM. Replacement is about ~250-300. Might be able to get it cheaper at the junkyard, but there's always the uncertainty of whether its good or not.

 

[rangerrick747]

Went to get PCM from local parts store, they told me I'd have to get the dealer to flash the memory for me. First I'd heard of that. Is this true??

We were cleaning up the work area and reattaching bits and pieces when i noticed a connector in the lower passenger side mounted to the wall. It had grey/red, black, green/white and green/orange wires running into it and then running out through the other side of the connector. When I wiggled it, the dome light on and off with the passenger door open. This was very odd to me. Looking at the wiring schematic, i noticed the grey/red wire is connected to multiple sensors and other items, but I don't understand why it would be running on the passenger side of the car.

So I pulled it apart and checked voltage, on the male side of the connector I got 9.45V on the grey/red wire, nothing on black, nothing on green/white, nothing on green/orange. When I accidentally cross the grey/red and black (ground) together, the dome light came on, the door ajar light signaled.

When this whole nightmare started, the low beams appeared dead, when we went to replace the light bulbs, the car was dead. When I replaced the battery, the low beams returned with good intensity. According to the wiring schematic, the green/white wire is responsible for the low beams, with the junction broken and the KOEO, the low beams are non-existent.

Would any of that be related to the ranger not starting????

So confused..help appreciated.

rangerrick747