Hey All,

Truck: 2000 F450, 7.3, 246,000 Miles.

This morning, after a bunch of stop and go traffic and then running some highway miles, truck stumbles and stalls as I was slowing on the exit ramp. Got it off to the side, cranked it and it started, but then stalled again. Cranked it again and it fired up and ran fine.

When I got to my destination, a few miles away, I checked as much as I could and didn't see anything that threw up a red flag. Just for giggles (because I have been down that road) I changed the CPS. I have two new ones in the glovebox.

Heading home this evening, after a few highway miles and then a bunch of stop and go traffic, truck stumbles and stalls again. Again got it off to the side, but this time it took quite a bit more cranking to start. Ran fine the rest of the way home.

At no time were there any CEL light, it was like the truck ran out of fuel.

I am thinking either fuel pump or fuel filter - any thoughts???

Thanks

Rich

 

It could be fuel related, but I would look at the ICP sensor first. Pull the connector off of the ICP sensor and look for oil residue on the pins. If nothing is found, don't rule it out. A biased ICP can cause the PCM to lower HPOP pressure via the IPR. If your HPOP pressure drops too low, it will stumble and die.

 

woodnthings

I would agree it might be a problem, and I could even see something like heat soak being the cause (both times, the truck had been running for about an hour), but why then would it start right up and run fine, both fast and slow, right afterwards? I would think the ICP would remain biased, and cause the truck to die each time idle was called for.

Would a fault like this store a code in the PCM? I have an AE and was going to check it in the morning (too dark now).

I am thinking fuel pump is getting ready to die, it is original.

Thanks

Rich

 

An ICP sensor can cause that. When pressure is higher than actual the PCM will command the IPR to get rid of oil pressure. If you happen to be coming down to an idle, the PCM may dump too much pressure and it will stumble then die.

Hard to start could be caused by a number of things including the fuel pump. If you ran the bowl out of fuel or it could be the ICP is not registering enough pressure too. You may not have a code as the PCM thinks it is normal. It saw high pressure and regulated it down. The PCM doesn't know when the engine dies due to oil or fuel starvation.

You should check your fuel pressure, also check the harness on the engine for shorts. I have seen the IPR wire short out and cause random die cycles. It was also heat/time related or so they thought.

 

Woodnthings

THANKS!! You were spot on with the ICP sensor, pulled the wire and there was oil under it. When I plugged in the AE, with the old sensor, I was holding (per the PCM) about 700-750 PSI. After I replaced the sensor, the AE was reporting about 500 PSI. This supports your theory of the sensor having some type of bias perfectly. The one thing I didn't think to do was to check the ICP with the old sensor, with the key on and the engine off, and see if there was a pressure showing. I can't really complain I guess, it was the original ICP sensor, with 11.5 years and close to a quarter of a million miles on it, but a hundred and a half seems kinda steep for a sensor that can fit in your pocket. At least on the 7.3 it is one of the easiest sensors to get to.

Anyway - I am rambling

Thanks again -- Reps Sent

 

Glad to hear you found it and didn't have to spend a ton of time or money fixing it!

Thank You for the reps! Always appreciate them!

 

I thoroughly cleaned the ICP connections and it still bucks.
Changed fuel filter and CPS too.
Also poured in Diesel Kleen.

 

They are cheep, try a new one.

 

What problem are you having in detail? Just jumping into a post isn't always the best route. Often times it is a single detail that may trigger someone to provide the correct diagnosis. Do you already have another post for your problem?

 

Dang, sorry bout that Ken, I put that in the wrong thread!
I was searching issues like I was having, stumbling and such.
Here is where it was supposed to go:
https://www.ford-trucks.com/forums/1...when-cold.html
This issue spans the earlier models of the 7.3 and even 6.0 engines.

I'll try my semi-local International dealer Monday.
ICP is up top, not underneath as on earlier models.
Do I need a standard 5/8" crow's foot wrench, or is there a certain degree of bend that I need?

 

Only $69 on E Bay. In the Ford sealed package.

 

All the listings say for the 6.0L
But they are the same part number.....
So, is that some sort of disclaimer, or???

I'm looking for the newer version that you can slip a socket over.

 

Here is what you need, make sure you get this P/N. Other numbers may not fit. Quite a few sellers were selling course thread ICP sensors and they still do.

Riffraff Diesel: Motorcraft ICP Sensor 97-03

 

Thanks Ken...
Do you know if the difference between the coarse and fine thread versions are obvious?
I can zip down to the International dealer tomorrow, their prices are usually really good.
So I'm guessing the 3C3Z-9F838-EA is coarse thread, even though it is listed for the 7.3?
And the F6TZ9F838A is fine thread?

 

You need to ask International for this number : 1807329C91

The 3C3Z-(F8383-EA is for the 03-07 6.0 trucks.