I have a 96 F350 that I haul freight with over the road. A few days ago while headed back East from Arizona it would make a weird noise while idling periodically like it was about to die, but it would catch right before dying and continue to run. I continued on thinking the cam sensor was about to go out. I was in the middle of nowhere. A couple hours later whenever I would hit the clutch in preparation for slowing down at a res light, etc. It would die. You release the clutch while it was still rolling and engine would catch and continue to run. A couple hours later I rolled into Dalhart, TX up in the Pandhandle where it died on me when a red light turned really fast. It never fired again. I bypassed the clutch position switch and got it to pull itself up into a parking lot without ever firing. The next morning all fuses checked ok. I walked across town to Napa and picked up a cam sensor. No change . 6 hours later when I was checking circuits with a test light a guy stopped by and said he was going to send their diesel mechanic over who works on their fire engines. He checked to make sure fuel was in the filter housing which I had already done. Next he went to get his computer to get check engine code. It was an ICP Sensor fault. So we went back to Napa and got the sensor, installed it, and cleaned the pigtail. Still won't fire. Computer shows no volts going through. Test light shows pigtail is hot. Guy said he didn't know what else to do. No other codes came up. So I asked him to pull start me. He didn't understand how that worked so I explained the concept, that I had a tow strap, that I would put my truck in 3rd, etc., and wave at him when it started. After finally grasping the concept we took off. Truck started ironically as we were in front of their shop. Check engine light was back on. Guy put his computer on it to clear codes, and it killed the truck of course. Wouldn't fire back. Pull started me again and it started right up. Guy unhooked and drove off. I drove down the road a mile, turned around, and headed back. As soon as I was in front of their shop again, ironically, on the other side of the road headed back East truck had two huge hiccups sounding like it was coming from the back of the cab (exhaust) and it sorta dieseled out pouring more white smoke than you have ever seen in your life. Looking up the road it looked like you were driving through a wild fire. Guys across the road came out of their shop, looked across the street, closed all their overhead doors and went back inside. After truck died I let it set a minute, hit the key, it fired, and I took off. Check engine light back on. It had another huge fit like that before I got out of Dallan County that was so bad that people pulled over on the shoulder and ran up with a fire extinguisher, but it wasn't on fire. Five minutes later it started back up, check engine light off, and it ran smooth and strong the rest of the day. Stopped last night in Missouri, and around 5am it died while idling. Cranked it over and never fired. Went inside, brushed my teeth, go coffee, etc., came back out... barely touched the key, and it fired right up. Any ideas. Owned several 7.3's, but I've never had anything this. This truck has 326,000. I have a 94 at the house, same configuration, 640,000, and it has never had symptoms like this either. All input welcome!

 

Something odd. Usually burns 5 gallons of fuel when idling a whole night. Last night it burned only 2.2 gallons.

 

Sounds like too much idling has killed compression..... Just a guess as I have seen a couple 7.3's that had a ton of idle hrs on them and they were shot. No Compression left, hense the no start while crank, but will start with a pull.. Just a guess...

 

Possible I guess, but this is low miles for a 7.3. Feel like it's more a fuel / sensor issue

 

Normally when you crank truck over it will puff a little smoke until it starts. Since this started happening it no longer puffs smoke as it cranks

 

It is generally recommended to use Ford or International sensors on these engines. It seems like aftermarket sensors don't play nice with them. I'd try a Ford or international ICP sensor. Do you still have the NAPA CPS installed? If so definitely get a Motorcraft one, as there have bee several posts where the aftermarket CPS do goofy things to the 7.3.

 

I had heard that in the past, but I generally have good luck out of Napa's Echlin Line. The Ford dealer didn't have it in stock. Just had another episode in Missouri. Exiting on the ramp for fuel when it started to die on the exit ramp. Fellow stopped to give me a pull start. Fired up after 2/10 of a mile, but then a red light turned, and I couldn't hold the idle. Took another mile before it fired and stayed running. Filled it up and added some more Diesel Kleen. Still rolling at the moment

 

Usually the CPS just causes run - no run issues, your description is a bit different. Sounds like a high pressure oil issue, maybe the IPR or ICP. You can just unplug the ICP sensor and computer will use default values. It should start and run, not as well with a good ICP connected though, a good troubleshooting technique when on the road. CEL will illuminate with it unplugged but it won't hurt anything. I'm assuming you did check the oil level on the dipstick, had to ask?

 

Yes oil level was fine. Even in the past when that low oil level sensor was engaged due to a blown o ring or something truck would always start; just wouldn't budge when you stepped on the accelerator pedal until you added oil. We tried unplugging ICP yesterday, but it still wouldn't fire.

 

Have you checked the fuel pressure while cranking or idling? Pretty simple to do with a tire style stick air pressure gauge. Just throwing stuff at you because we don't know what has been tried. Do you still have the original fuel pump in the rig as they seldom last more than ~200K.

 

Just had another huge back fire through the exhaust. White smoke poured out everywhere. After it dieseled out and died waited a couple minutes and it fired right up. Check engine light now off. Seems to be surging a bit on the accelerator. Diesel guy in Texas checked fuel pressure yesterday and said it was fine

 

Disregard since you already checked the fuel pressure.

 

Haven't ever changed fuel pump on this. Was told in 96 there is only an injector pump; not a secondary fuel supply pump or anything.....

 

Cruise stopped working a few days ago when symptoms started, but I believe Thai can only be coincidence....

 

All the 7.3s, up until the new body style in the early 99 model year have a mechanical 2 stage fuel pump located in the valley a little ahead of the turbo. There is no injector pump on any of the 7.3 strokes.