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Low Injection Control Pressure (ICP) Making life interesting
Posted to HD/Fleet Forum on 4/26/2014 10 Replies

I just wanted to share this on iATN as I feel that I have not contributed much lately. The above truck was brought to us from another shop that found a low ICP concern. The truck shut down on the customer and would not restart until it cooled off. After that it would only run for several minutes before stalling again. A pretty straight forward issue on a 6.0L.

First, I scanned the PCM and found a low ICP while cranking code. The oil level was good but the oil was dirty. So, I flashed up the truck and watched the data stream. Right away the IPR duty cycle is a little high at 30% but the engine was cold. Within 2 minutes it started to climb to 85% and was unable to match the desired ICP value. Shortly there after, it stalled.

With the ICP sensor in the HP pump cover on a 2003 engine, I removed the left valve cover and performed the air pressure test. Right away I could hear a leak internal to the engine with the IPR closed. The air leak could be heard loudest from the oil filter stand pipe. From my experience this indicates a damaged piston-block in the swashplate pump such as this.

[2003 Ford F-350 Super Duty Lariat, Engine/Propulsion Photo]

The IPR had some small metal debris in the screen and the ICP sensor was leaking though the sensor bias was still good. So, I quoted the job with HP pump, ICP, ICP pigtail, IPR, oil change and all needed gaskets. Also, I would change the reservoir screen under the oil cooler. The quote was approved and the work began.

With the truck back together is started right up. I idled it for a while and watched the IPR duty cycle. It was still a little high but the system did have air in it. Unfortunately, this was not the case. The IPR duty cycle started to climb once again. This time though it did not stall but ran at 85% all the way up to operating temperature.

Great, off comes the left valve cover again and more air pressure testing but no leaks were found. I rechecked the IPR screen and tested the electrical circuit to the IPR, all were good. An interesting note is that the IPR % shown in the IDS data logger is not actual duty cycle. At 95% commanded, I saw 64% on the signal, much like a 7.3L. Next, I blocked of the left rail and cranked. Okay here is the interesting part, pressure went up to 1100 psi when 2300 psi was commanded but on the next crank I could only get 360 psi. After sitting for a while the same thing would occur, enough pressure to start and then 360 psi on the second crank.

At this point I started second guessing myself. I know the original pump was bad and under closer examination I found the drive shaft seal had blown out of it. I used a Bosch Rexroth pump which is the OE unit. Did I miss something on installation or did I get a bad pump? Base engine oil pressure was good so it wasn't a supply issue as pressure is measured virtually in the reservoir. My next move was to test the flow of the HP pump. I measured 240mL/10sec of cranking, which is a very good reading from my experience. Generally, 160mL area will barely run the engine.

Knowing that I was only pressurizing the system to 150 psi and my issue was at 360 psi or 1100 psi, I removed the right valve cover to block off that bank. With just that bank blocked off pressure spiked to 3600 psi and settled down at the desired 2300 psi. Was it an injector leaking, the STC fitting or the rail itself? Well it was a mess. The oil rail was loose. There were stripped bolt holes and broken bolts. The last mechanic under here had created quite a mess over torquing the hold down bolts and tried using longer ones (of a lower grade) to patch it together.

With this repaired the system has no problems building pressure. Now I know using nitrogen at a higher pressure would have found this problem but I just wanted to share in my fun for the week.

Ryan from British Columbia

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car Vehicle Data

2003 Ford F-550 Super Duty XL 6.0L No Start, Stall

Engine6.0 L
Trans6-speed Standard
SymptomsNo Start, Stall