I tried searching around but I am lost at what to do next. Got intermittent crank but no start. Occasionally I can go and turn the ignition and truck fires up perfectly and I can drive it around with no problems. Then next day I go to start it and just crank but no start. I got fuel pressure but no spark and the injectors are not firing. I replaced the cam position sensor but still no fix. Tried swapping around relays and looking for loose wires etc... but found nothing. Any advice on what to do next???? Also I have no trouble hooking up obd2 reader and no fault codes are found.

 

Have you checked the coil(s)

 

I am not sure what you mean by check the coils. Could this cause the problem in question????? I am not getting any spark and injectors not firing so I am confused.

 

I'm not sure those two problems are caused by the same source. For spark the coils need to be working. Check resistance on coil paks and see if there is any damage to the paks. If there is no problem with the coils then the issue may be the ECM or ECM wiring.

Was there any repairs done to the vehicle before the problem arose ?

 

Well bought the truck drove it around for a couple days then parked in my garage. Worked on a loose connection going to red wire and there was a large prolonged spark. I did start it up after that and all seemed fine. I went and gutted the interior and power washed interior and tried to not get critical components wet but who knows. I have removed ecm and looks in perfect condition with no water or nothing. I know it can still be bad but I am kinda reluctant to swap it out before I troubleshoot any other things that could be causing this.

 

troy98f150,
A 1998 F150 has COP and so, you pulled a coil and verified the no spark? They, (all 8 coils) would not all have failed at once
The fuel pump is failing?
If you have no codes and system pass out of a scan tool
The problem will be fuel related
In your case after power washing the inside of the cab, anything could have happened
Install fuel pressure gauge and interrogate the fuel system
Check every fuse in every panel

 

I have done the things you said. Got 40 psi fuel pressure and checked all fuses and have swapped around many times the relays and still nothing changes. I am able to read the ecm with an obd2 reader and it shows no codes. I just need some place to start to get my troubleshooting started?????

 

A 98 with a 5.4 had COPS. The 4.2L and 4.6L engines used conventional coils.

It helps if you definitively identify what you're working on, including the engine. There are differences.

 

It is a 98 f150 xlt extended cab with 4.6 engine and automatic transmission.

I hooked up my obd2 reader and while I can connect up just fine I am unable to retrieve the vin number with the scanner. Does this point me in any direction to troubleshoot this fault?????

 

Not necessarily.

Does your reader have the capability of reading live data?
Do you have a multimeter and know how to use it?
During a failed starting attempt, what happens to the check engine light 1) when the ignition switch is turned to RUN (not START) and then 2) to START. That's a two-stage observation.
How, exactly, did you determine that you've "got fuel pressure but no spark and the injectors are not firing"?

 

It just takes the big 3 to start
Fuel
Spark
Compression
You are missing one of those

 

Yep. It just requires each to be there in the correct amount and at the correct time.

 

I have hooked up noid and spark plug testers and verified that these are not present when there is no start. I verified proper fuel pressure to the rails with a pressure tester.

When the engine will start I turn ignition to run and check engine light comes on and goes out when I turn to start. When the truck does not start when I turn the key to start the check engine light stays on and this is a clear indication that the engine is not going to start.

No matter when engine starts or not I am still unable to retrieve the vin from pcm. I just bought the truck and never checked to see if I could retrieve the vin so not sure if something is wrong or sometime in trucks 24 years a blank pcm was installed. I don’t really care if I can retrieve the vin or not as long as car runs and starts ok.

I checked I am getting power to pcm relay and have swapped relays many times and does not seem to be a bad relay.

At this point very intermittent and can not risk driving truck anywhere until get the problem sorted out. Any ideas. Could be a bad or intermittent pcm or even bad gem module. Any help is appreciated.

 

It may be the wiring. Maybe a loose connection somewhere (?)

 

This usually indicates that the PCM is not getting a valid crankshaft sensor (CKP) signal. I'd focus on that circuit first.

If your instrument cluster is equipped with a tach, it should be moving slightly while cranking. If it's flat-lined, that's another indication the PCM isn't getting a CKP signal.

FWIW, it is critical that if be understood the criticality of the CKP sensor's signal. It is the heart of everything electrical and without it, the engine will never run. No spark, no injectors, no fuel pump re-start.