New to the forum and to super duty. Looking for help advice.
I have a '99 F250, 7.3, CCSB with just over 127K on the clock. I went out of town for 10 days and was ready to get out of the grocery getter and into my truck. I hop in and it cranks great but would not start. I pop the hood and start with the easy stuff. Made sure all plugs/connections were good, check. Relays and fuses are still in good order (under hood and dash), check. Fuel pump was replaced less than a month ago (works great) with fuel in fuel bowl (new filter), check. Try to start a few more times with no luck, so I tinkered around for few more minutes and it starts right up and drives perfect. Drive around, truck is on and off as usual throughout the day and go back to work next day around 10:30. Truck starts as normal. Get to work and have to run out but truck doesn't start again. After key is in on position for 15-20 minutes while checking fuses and such it starts up and runs perfect. I drive around for 20 minutes and return. I got off about 5 hours later and it doesn't start. Leave key in on position while I'm explaining issues to a buddy again 15-20 while key is on it starts right up. I drive home and park and I haven't been able to start it since.
I need some direction or advice on where to start. From reading forums and watching you tube I'm leaning towards IPV or CPS but no one has described the problem as I've had.
Please help. I do not have monitors, tuner, or anything aftermarket but I'm a mechanic and have a descent set of tools at home.

 

Couple of questions to help point in the right direction.

When you turn the key on, and then crank the engine, do all the dash lights come on and go off like normal? Or do some lights stay on, or not come on? (wait to start light and glow plug light are important ones)

When you crank the motor and it doesn't start, is there any smoke coming out the tail pipe?

Does the tach bounce while cranking?

What do you notice that's diferent when it finally does start up? Sounds, timing, etc?

 

All dash lights are normal. WTS light comes on and turns off in normal time. I'm not 100% on GP light as it is about 90 degrees during the day. No SES light. Nothing out of the ordinary.

There is a slight amount of smoke when trying to start it.

The tach bounces up to maybe 150-200 RPM.

When it started last, it ran normal. No rough idle even at the beginning.

 

Check the wires on the bottom of the 42 pin harness, sometimes they can brush against the valve cover and create a connection you do not want.

 

If you're getting smoke while cranking, first check the engine oil level. Next, how many miles on the current oil? Last, try plugging in the block heater for a few hours before you try and start it.

 

Haven't had the chance to check the wires yet but will today.

Oil level is between the hash marks on dip stick and less than 500 miles on oil. Rotella 15/40 oil and motor craft filter.

I'll plug it up while I go grab lunch.

I'm also going to pull the IPR valve and disassemble and clean it. Is there any way to test it?

 

Wire harness looks good.

Block heater didn't make any difference.

Working on cleaning IPR valve now. magnetic relay had 10ohms across its plug connector. There was no sound when shaking valve. Oil looked pretty good in it.

 

Cleaned and replaced IPR valve. Attempted to start. No smoke from tail pipe. Charging batteries now. I've got them low on charge from starting attempts.

 

If it still does not start, you can unplug the ICP and it will default to a value that will allow the truck to start, if that is a bad part.

That is another free and quick check.

 

Tried that, didn't start.

No smoke from tail pipe. Batteries at full charge.

Any other suggestions?

 

You did have it plugged in for a few hours before you tried, correct?

The next step is either start throwing parts at it or get a scanner so you can monitor live data and get more information about what problem your engine is having.

Forscan seems to be the popular one these days. It's free to download on your laptop, you just need to buy an OBDII connector so it can read the truck. (less than $100)

 

Thanks, I'll look into that one.

 

Upon further inspection I found this guy on the passenger side injector harness. Haven't got the chance to pull it all the way apart yet. This can be a good sign. Anyone have the slightest clue of why something like this would be there?

 

Well that certainly would not inspire confidence in the previous owners ability to do anything. Was it hooked up to or plugged into anything? Have you had time or the chance to trace it out to see where it goes? Since it has no shielding on it, I would assume it was used for a ground connection, but that is just a guess.

 

It didn't appear to be connected to anything but I haven't had the chance to trace it out. I'll post the results when I get to the bottom of it.