[Jack E]

Hi all - first time on this part of the forum. My 2000 f250 5.4L is having some starting issue and I'm in the process of doing some electrical troubleshooting for a fuel delivery problem. Is this the correct fuel pump power-up sequence? - turn Key - power to PCM relay - power to PCM - power to fuel pump fuse - power to fuel pump relay - power to fuel pump inertia switch - power to fuel pump.

I don't have a wiring diagram. I think I've narrowed it down to something before the inertia switch.

Thanks

 

[Windows on Wash]

Is it not starting or just hard starting?

 

[Jack E]

Starts hard then runs normal. Have done fuel rail pressure check and preliminary circuit checks. Seems to be a problem somewhere along the fuel pump circuit. Feel reasonably confident the fuel pump is OK.

 

[cjm94]

If it starts and runs your fuel pump circuit is fine. Sounds like your fuel pump is losing its prime. There is a check valve in the fuel pump so the system holds pressure. when it goes bad you will have a long crank. You need to hook up a pressure Guage cycle the key fuel pressure should not drop. If it does you need a pump.

 

[Jack E]

Thanks for the replies. When I check the fuel pressure at the rail I get zero pressure when I turn the key. The system should pressure up when I turn the key. It pressures up after a number of attempts. Once pressured up it starts and runs fine. It's holding pressure after I shut down. When I attempt to start it later it almost fires up but then nothing(fuel remaining from last start.) I've checked the power to the intertia switch (comes from the fuel pump relay.) I get power to the intertia switch after a number of attempts turning the key.

It seems like there is a "break" somewhere in the fuel pump circuit. Today I'm going to check for power behind the FP relay; start with the fuel pump fuse. Not sure about the path of power from the key-on to the FP relay. Trying to figure where I should be checking for power along the circuit. :huh:

 

[1985gt]

Check valve in the pump, regulator, or injector(s) will all bleed fuel pressure.

This may help. http://performancefuelsystems.com/tech-leakdowntest.html

Basically if you hook a gauge up, start it then shut it down, watch to see how quickly if at all the pressure drops off, if it's quick it will most likely be the regulator or check valve in the pump, if it's slowly then it's an injector.

Need to check the fuel delivery problem also, see if the injectors are firing normally at start up, to check them you can rent noid lights from most auto parts stores. Simply unplug the electrical portion of the injector and plug the lights in, watch to see if they flash or not.

A quick way to check and see if it's a fuel system problem or a fuel delivery problem is do this.

Let it sit for awhile, turn the key to the ON position, but not start, listen for the fuel pump if you can hear it, if not give it 5 seconds in the ON position, then turn it back to off, then just for good measure do that cycle one more time, after that try and start it normally, see if it starts any better. If it does then is a fuel pressure/system problem.


Another thing to check is for external fuel leaks, it may be leaking someplace that isn't noticeable, also when was the last time you changed the fuel filter?

Like the other said the electrical system for the most part is on or off, it works or it doesn't and the fuel pump is the same, very rarely does a fuel pump start to go out or work intermittently.

Another thing to check for good measure is the condition of your battery, it may not be in good enough health to run everything properly, a weak battery causes all kinds of weird issues in some vehicles. Most auto parts stores will load test them, on or off the vehicle for free.

 

[Jack E]

Thanks for the suggestions:smile:Your comment below is the essence of the problem:
"Let it sit for awhile, turn the key to the ON position, but not start, listen for the fuel pump if you can hear it, if not give it 5 seconds in the ON position, then turn it back to off, then just for good measure do that cycle one more time, after that try and start it normally, see if it starts any better. If it does then is a fuel pressure/system problem."

When I turn the key on I don't hear the fuel pump. I've confirmed the fuel pump is not pressurizing by observing no fuel pressure at the rail and no power going to the fuel pump relay under the dash. When I turn the key on and off about 4-5 times the fuel pump powers up normally, fuel pressure normal, runs and idles normal. Today I found a ground wire that the fuel pump circuit uses. I cleaned the ground really good and it started first time - was warmed up though. I'll check tomorrow when cold. Maybe a simple ground issue:vs_worry: Thanks again.

 

[Jack E]

Trucks been starting normally for the past couple days. Looks like it was the dirty ground. When will I learn - always check the simple things first. :smile:

 

[1985gt]

Yeah, always the simple things first. My truck was cranking slower then normal lately and the clock and HVAC would reset. I was hoping the batteries weren't on their way out since it would be like 500 to replace them both, checked the connections and main grounds and found one positive somewhat loose, just enough to do what it was doing. Haven't had the clock reset or HVAC reset since then and it's been colder. Keeping my fingers crossed.

 

[Brainbucket]

Back in '02, I was new in a GM dealership. I started in '79 in aftermarket world so I have been around. Brand new in the dealership and they wanted to welcome me with a problem car that no one could fix. 01 Vette would do fine then just suddenly die or would not start. I got the car and being me, I looked up the history on this vehicle. It had been to this dealership 14 times for the same problem. Customer wanted another car and didn't want this car back since we couldn't fix it. Service manager smiled at me and told me good luck. I put the car on the rack and it looked beautiful under and over. Clean as a whistle. First thing first. I checked voltage. Fine. Checked grounds. Found 8 volt drop at the main engine to battery ground. It looked brand new. Clean. But when I pulled the bolt out of the engine block, black crap came out. Aluminum does not like copper when mated for electrical contact. It corrodes. I cleaned it and put die electric grease on it. Bingo! No more voltage drop. Car ran great. You would not believe how many times I fix cars with a bad ground. Just because it looks good doesn't mean it is.:vs_coffee: