I've got a 1999 F150 4.6 with 0 spark. In Nome there aren't any fancy shops with magic testing devices so I'm on my own (me and Chilton). I changed the Crank Pos. Sensor, and sent PCM to AES for rebuild. 5 weeks later I got the PCM back and still no spark. Checked + to coil plug o.k. Hooked LED light to - side of coil plug and to +side of batt. No Flash, just a steady green light when cranking. Sent away for a Code Reader, it thinks for a while and then reads Code Error! Its a good thing you can still drive a snomachine in town. Any suggestions?

 

One small bit of information- I believe there is ALWAYS + juice to the COP's, the spark is created when - (negative) is introduced to complete the circuit and create the spark (I believe by the PCM). There have been numerous times on the truck forums when people say I have + to the COP's but no spark. That's they way it's supposed to be until negative is introduced at the appropriate time to complete the circuit. If this is incorrect in any way, I'm sure someone will set it straight. If the LED between coil neg and batt. pos. was steady green (indicating constant ground) and the PCM was supposedly rebuilt, you need to find out from someone what triggers the PCM to introduce the ground at the correct time. Was the CPS a Ford part or aftermarket? Was the juice flow through the LED the correct direction? Guess it wouldn't work at all if it's the wrong direction.

 

Damn! Keep the sled dogs fed.. Just in case

 

A little history may help. How did this failure happen? Were you driving and the truck quit, did it just refuse to start after sitting, did you perform any repairs to the engine prior to this failure such as removing the front cover etc. You should have coil packs on your truck as well I believe.

 

I actually bought the truck from my neighbor who couldn't fix the problem. He believed it was the pcm. He said he ran it through a creek and his 4x4 went out and he brought it home and it didn't start again. Yes there are coil packs and not cops.

 

I am wondering, when I connect the LED test light to pos. batt. and the negative coil harness connector why would I get a steady light and no blink when it is cranked over. It seems that if there was a short to ground on the negative side it wouldn't be on both negative connections going to the coil unless the short to ground somehow went through the PCM. Any ideas??

 

Thanks for the response. The CPS was from Carquest (the only parts store in town) All my mechanical experience is with distributor or magneto fired engines. I know an old style coil sends out a spark when you open the negative side by opening the points. I imagine that the PCM should take the place of the points and the CPS should tell the PCM when to open the negative. I just hope AES didn't screw me on the PCM rebuild.

 

The reason I figured the PCM rebuild would fix the problem is that AES called after they received the PCM and said, "Gee this PCM is not worth rebuilding, how about we send you a remanufactured one instead for another $100.?" I agreed and assumed that this must mean that my problem was for sure in the PCM, but no luck.

 

Thanks for the "Technical" advice. Actually feeding the dogs is easy, its cleaning up the crap that is the challenge.

 

Right, - just like engine problems.- They both add up when neglected.

 

Does that mean the 4x4 went out and left him stranded in the creek only to have to leave it submerged (however deep) until it was pulled out? Have you checked all the main fuses and relays? I would also be checking for the existence of pressure at the fuel rail. It's possible the inertia switch (passenger kick panel) has been tripped and there is no active pump. Should be able to hear it prime with the key in the on position.

Nome, wasn't there some alien movie based on a true story in that town. Ahh, the fourth kind?

 

Thanks for the response. There was a movie. It wasn't filmed here however. We got no trees!

No it wasn't left in the creek as far as I know. Do you know whether a problem with the fuel system can affect the ignition spark? Where do you listen for the noise of the fuel prime? I checked the fuses but not the relays yet.

 

No, it wouldnt have to do with spark. But a rule of thumb anytime you have a starting issue is to check fuel also. Not sure if the test being done on the coil pack is indicating a no spark issue? You should be able to hear it from the cab with the door open. When you turn the key to the on position listen for a whining/humming noise coming from the fuel tank that should be a nice consistent sound lasting 1-2 seconds. That is the pump priming. It's worth checking, sounds like if it was in a creek there may have been some offroading going on? Which could have tripped the inertia.

 

Have someone listen to the gas tank at the cap, with the cap off while you or they turn the ignition switch to the on position. Should hear a hum for about 10 seconds..

 

The very first thing that goes through my mind when you say it stalled after going though water is hydrolock. The 4x4 is also vacum activated and the fact that he lost that could mean vac was lost as well? I know you can crank the engine over but that doesn't always mean there has not been a hydrolock and compression or timing was lost. I personally would run a compression test first just to confirm the base engine is capable of actually running. If base engine has been compromised you can change parts forever and never get it to run. JMO.