Okay guys so im a little stumped.. I have a 2002 7.3 F250 the inssue im having is no matter how many times you crank it it will not start and will only crank unless you plug the block heater in for about an hour and twenty minutes. Keep in mind its been about 95° where im at everyday. Any ideas?

 

When it does start it runs rough and has doesnt have alot of power.

 

Get a J1850 PWM compatible scanner and pull codes. A lot of us on here like FORScan paired with a good OBD dongle. There is an entire section in the Tech Folder at the top of this forum that teaches you how to use it. You may also be asked to log data and plug it into this tool to aid in diagnosis.

 

When was the last time it ran? Did it die or was it ok when parked?

Lots of threads and even flow charts on no starts. Check the Tech folder.

Crank = Engine rotates with key in crank position but does not fire.
Start = Engine runs on it's own after cranking event.

I'm a little confused with this statement....


Does that mean the engine will only crank after the block heater is plugged in, or will only start after the block heater is plugged in? It makes a big difference...

What are your battery voltages (disconnected from the truck)? When was the last time you charged the batteries?

Without more info I would suggest charging both batteries at least 24 hrs and checking voltage. Read up on float vs resting voltage.
If charging in the truck make sure both batteries show equal voltage while charging. Any difference indicates resistance in the circuit.
If either battery is under 12.3v resting voltage after charging replace it with a known good one.
If either battery is between 12.3-12.5 I would only attempt starting with an additional, auxillary 12v source.... 50A jump assist from battery charger or jump pack, heavy guage jumper cables from a running vehicle that has similar sized or larger battery.

Welcome to the forum!

 

Do you have any gages or ways to read parameters (e.g. Torque app)?

From another thread:

There are plenty of troubleshooting threads (posted or updated almost daily) on this but, for some reason, it's hard to find what actually needs to happen to start the truck. That being said there are some specific parameters that the PCM is looking for before it gives the green light to the IDM to fire the injectors and bring the big block to life (these are all minimums while cranking):

1. Engine RPM - 100
2. Injection Control Pressure (ICP) - 500 psi
3. Injection Pulse Width (PW) - 0.6 ms
4. Volts - 7-10 VDC

There are nuiances between years but these are the four basic things your truck PCM needs to see while cranking before the IDM gets the go ahead to start injecting fuel.

Note: The 0.6ms pulse width requirement indicates that the PCM and IDM are talking and not an indication of actual pulse width. If the PW was 0.0ms then the IDM did not answer when the PCM called so it left a voicemail telling the IDM there will be no injection action this round.

 

Check your oil level

 

Sound advice!