I've been troubleshooting this for a while, and I'm still coming up blank...

I have a 2001 F250 Lariat Platinum SC 4x4 7.3. I just purchased the truck about 6 weeks ago. Mods are below. I've been experiencing a no-start issue. I can be in and out of the truck all day, but for no rhyme or reason, it will decide not to start sometimes. I will put the key in the ignition, turn it to "on" and the Wait To Start light will only flash for an instant, then extinguish. At that point, the truck will turn over all day long, it just won't fire. If I wait a while, (sometimes 20-45 minutes), and go and try the truck again, the WTS light stays illuminated for the appropriate amount of time (usually 10-15 seconds) and the truck fires right up normally.

I have worked with the dealership (they're stumped) and Jody at DP Tuner. The truck has the F5/F6 installed. The tunes have been updated.

Here's what I have tried: Jody indicated it was a power problem to the PCM, and the WTS light flashing only once for an instant was basically a brain-dead PCM. I checked all the fuses at the central junction box under the hood (particularly 19, 22 and 30 - relay) and replaced those two fuses and the relay. I pulled the PCM power fuse, and the truck didn't even let the WTS light flash.

The truck got a new windshield the day after I brought it home. I have verified, and had the windshield installation place verify, that there is not a water problem (moisture at the PCM).

I could pull the F5 chip, but the truck has single-shot injectors, and Jody assured me it would run like crap. That would be necessary to "just get me home."

The sure-fire solution I have found, if the truck won't start, is to pull the Junction Box Battery Feed, #22 (50A), and just re-install it. The truck fires right up after that every time.

What am I missing? Thanks.

Truck specs/mods:

2001 PSD 4x4 Platinum Edition Lariat Auto CC SRW
Swamps 175/146 Single Shots
DP Tuning
IC Foil Delete
ITP In-Tank Kit
Harpoon
ITP SS HPX
ITP OBA
6637 Intake
Marinco Mod

 

Have you noticed the SES light staying on when it won't start? This is a problem I have been having since I installed my DP. If I cycle the key until I get the SES light to go off, the truck starts fine. Otherwise, I'm dead in the water.

 

No SES light to date, and the light works. I have pulled codes using my SCT XCAL2, and I got P0475 Exhaust Pressure Control Valve Error and P0603 Internal Control Module KAM Error.

I did get my hands on AutoEnginuity's scanner with the Expanded Ford software, but I haven't had a chance to diagnose yet.

Maybe you could try my trick / work-around of pulling the #22 fuse (50A) and re-installing. I've success thus far in that it gets me back on the road, but it's kind of BS that I have to pop the hood and do that...

I'm looking for the appropriate solution, instead of just banging my head against the wall!

 

I too get the P0603 a lot. Some times AE will pull 10 or so very scary sounding codes and then they wont show up again for months at a time. Is the P0475 the valve or the sensor? I kept dismissing one of the EBP codes after my delete and turned out that my EBP sensor was dead.

 

Remove the key and pull the DP chip. Inspect the contacts on the PCM and the chip connection. Clean if necessary or consider re-tinning them if they've been cleaned too much. Also double check the connection at the switch.

Then I'd check the battery cables and grounds, as well as the fuses you replaced if you still have them and the 50 amp fuse you're pulling now. Look for any signs of corrosion or excess heat that might be causing a poor connection.

Jody's already told you the issue is with the PCM not getting power when this happens. If you see the light flash, save your batteries and don't bother cranking. Now it's just time to see if we can figure out what is causing the power issue.

It's not a fun process, but I'd do only one thing at a time so you know what fixes it.

 

Thanks, Chris. I forgot to mention, but I did uninstall the F5 chip, and re-install it in accordance with DP's instructions - I didn't do the original installation of the chip (previous owner), but I didn't see anything necessarily that I didn't like when uninstalling it (ie. previous workmanship). Based upon James and Jody's recommendation, after cleaning the F5 chip contact at the PCM, I did apply a light coating of dielectric grease.

The PCM contacts weren't cleaned too much, as referenced in DP's instructions. But in the event re-tinning is the solution, how in the world would I get that done?

The connection at the switch was less-than-desirable, as there is no locking clip to secure the connection. I ensured by situating the cable, with a little zip-tie magic, consistent pressure is applied keeping the connection secure.

I'll look at the battery cables tomorrow. There are 2 new batteries installed, about 3 months ago. But I did notice that the negative cables weren't seated as much as I would have done (loosen the clamps, large socket, dead blow, gently tap them to seat). When the WTS extinguishes immediately, I know I can crank all day and it won't start. So I don't even try.

A correction to an earlier post, the work-around to get me back on the road has been disconnecting and reconnecting fuse 22 (50A), Junction Box Battery Feed.

I'll continue methodically chasing what I'm sure is a relatively simple electrical problem. Many years ago, when I was still a mechanic on the Blackhawk UH-60, I spent about 3 weeks hunting down an electrical problem on one aircraft, through miles (literally) of wiring and hundreds of connections. Not fun, but it was satisfying to find the solution.

Thanks again for the tips.

 

Re-tinning is nothing more than applying a thin coat of solder to the connector strips on the PCM board where the chip plugs in. If the connections look good, this probably won't be necessary.

 

Thanks. That might be an option I'll have to try. Either way, I'll put that tip into my bag of "tools" in the event I need it in the future.

I did secure the negative posts properly on the batteries this evening. We'll see if that helps.

 

Do u have your fuel heater connected at the fuel filter housing? What if it has an intermittent problem that pulls on the relay and causes it to overload and disengage?

 

You didn't apply the dielectric grease to the contacts eh?

 

That's exactly what I did. Jody at DP explained that over time, corrosion can get into the contacts (where the F5 slides onto the PCM). I ensured it was clean, and applied a light coating of dielectric grease. Jody and James took no exception.

 

Removed the battery cables, properly seated them, and reinstalled. Truck ran great (multiple starts) all day yesterday, 100% precip all day.

On one of my stops today, she wouldn't start. Pulled good 'ol #22 in the fuse box, re-installed, and I was back on the road.

In researching the Haynes, in the absence of extremely cold temperatures (it's only been freezing a few nights so far this fall), I didn't see how the fuel heater would otherwise inhibit this starting problem.

I'm open for any more thoughts!!!

 

may sound dumb and I am ignorant related to electrical things but could something be bad in the fuse box itself?

 

Mine blew up at 80 degrees going down the highway...Do not know why but it did. Disconnected it. I am not sure when it activates it. Mine is deleted now since August with no issues.

 

I inspected the central junction box the best that I could, but access is very limited. All of the wires are fed from the bottom, so short of uninstalling the main wiring harness, there is not much I could even do with the junction box.

All of the connections look nice and clean, and I inspected every fuse in the junction box for corrosion, and cleaned the slight bit I did find.

I had thought that possibly there was a short or break in a wire feeding the junction box, but I haven't figured out a way yet to visually inspect below the junction box...