Measured voltage at inertia switch.....it is consistently getting power with key on for the 2-3 secs. But fuel pump is not running for the 2-3 secs. So that means either a bad connection to the fuel pump or fuel pump failing or failed? And yes, I'm getting 12V to the red wire of the fuel injectors with key on.

 

That would be my conclusion if the observation is accurate.

If you confirm that the power is presented to the pump but it doesn't run, no need to use a pressure gauge to tell you what you should logically conclude - if the pump didn't run, it didn't create pressure in the system. You're probably at the point of either dropping the tank or pulling the bed to access the pump. If a confirmation check of the pump's power and ground connections proves out, then it's time for a new pump.

However, that still doesn't explain the apparent mixed results with starting fluid and the lack of activity on the noids that you reported.
How about power at the COPs also? Gotta have that too.

If your cluster is equipped with a tach, you should see activity on it while cranking if the CKP sensor is active and the PCM and cluster are all working correctly (to that point, at least). Also, you should see the MIL go out during cranking if the CKP signal is present.

Trying to use a scan tool to observe cranking RPMs would require a tool with an independent power source. Vehicle-powered tools would likely be severely affected by the drop in supply voltage commonly seen at the OBDII port during cranking and may give results that are ambiguous, at best, assuming they continue operating during the cranking period.

 

Yes, red wire to COPs has power with key on.

Tach does nothing while cranking. MIL goes out while cranking.

I put a noid light in the plug to the COP - nothing while cranking. And the apparent "fire" with the start fluid is incorrect...A check with spark tester showed there is no spark. Is there any logic that prevents spark and injector pulses when the pump has failed? (Note: I replaced the crank sensor)

 

you can use a volt meter, you will have to probe both wires, set the meter on a/c volts and have someone crank it over and you should see .500 or more volts, the volts will vary as you crank it

 

Nope. The PCM does not monitor the performance of the fuel pump. It's programming simply assumes that it worked on this generation of truck.

 

Ok....sounds like I'm dealing with more than one issue......bad fuel pump and ????

SHO: During cranking, no activity on tach, but MIL goes out....you said I should see both of these?

Unplugged crank sensor and measured voltage while cranking....It's putting out a pulsing .5 volts

 

is the crank sensor plug factory or has it been replaced? I just worked on a 1997 truck and the connector for the crank sensor had been replaced, and it work for a few weeks and then quit running, I finally reversed the wires and it started right up

 

It's factory. Truck has spent entire life in AZ, only 73K miles. No corrosion, no salt. Plug to sensor is clean....no oil, dirt, etc.

 

Is this supposed to happen?: Removed Fuse 18 from engine compartment fuse box (BJB). Turn key to "on" and fuel pump relay (301) starts chattering rapidly and suddenly fuel pump starts running constantly, won't shut off until key turned off. (Fuse 18 is for PCM, Fuel injectors, fuel pump relay, and MAF sensor). How is that relay getting power if the fuse is removed? How is fuel pump kicking in if that fuse is removed? Do I have a PCM that's gone whacky?

Reinstalled fuse 18, turned key on/off a few cycles and could hear pump run for priming (2-3 sec) for three cycles. Fourth time - no pump priming when key on. In the next 10 or so key on/off cycles, pump ran (primed) at key on once.

 

F18 has no effect on whether or not the FP relay energizes or not, it supplies power for the load of the relay, not the coil.

I would not eliminate that from the list of possibilities. However, it's incumbent on you to first verify the integrity of the grounds and power that the PCM needs to function properly before reaching such a conclusion.

 

I've got power to the red wire of both the injectors and the COPs. Crank sensor seems ok, putting out 0.5V. How can I test to see if Crank sensor signal is getting to PCM to enable to activate what's needed to start? The PCM will not start the fuel pump just simply based on signal from the crank sensor, it needs to see that the engine has started....is that correct?

BTW....I was wondering if I could hear the fuel pump run but not pressurize the fuel rail (little hose coming out of pump broken or detached inside tank), but I put the gauge back on the fuel rail and with F18 fuse out, it lets the pump run and fuel rail pressurizes to about 33 psi.

So seems like I have things happening correctly to produce a start, but I'm obviously missing something. Is the next step to determine if PCM is getting signal from crank sensor? If so, how can I do that?

 

a scan tool is the easy way, another way is to probe the two wires for crank signal where they go into the pcm

 

I'm sure several of the experts on here have the factory service dvd's....can someone post the PCM pinout diagram.....2003 5.4L supercrew 4x4? Thanks.

 

I replaced the fuel pump but still won't start. Fuel pump had definitely failed....applied power on the bench and it would run for a sec or two, then freeze up. This explains why I would only hear it prime every 10th key on/off cycle. With new pump, I can hear the 2 sec prime every time key is cycled on. With gauge on fuel rail, I'm reading 35 psi.

When old pump freezes during bench test, my power leads will really spark...I'm assuming from an internal short. I'm wondering if this has led to an electrical failure elsewhere. I went back and double-checked all the fuses and all are fine. Could a shorted out pump have caused a failed circuit in the PCM? That doesn't seem likely since the pump is protected by a fuse.

Any suggestions? I really miss my truck and am approaching that dreaded call to the tow truck....

 

the pins you need is number 21 and 22 at the pcm, I just googled a pcm pinout for your year truck and found it there