A PSD "No Start" Puzzle - Diesel Truck Forum - TheDieselGarage.com
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post #1 of 6 (permalink) Old 06-06-2010, 07:22 PM Thread Starter
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A PSD "No Start" Puzzle


I have a 1996 E-350 with the 7.3 PSD. The vehicle was well maintained, and ran like a top when it went into a dry, temp controlled garage in which regular starting was not an option.

Page forward 3 years and I'm back at the project vehicle, and have it in a new shop, and after some fluid changes and checks I gave it a crank; it caught on the third crank for about 10s then puttered out.

No Codes.
No smoke while cranking.
No Starting.

It hasn't caught since, and I have checked out the:

Fuel System
  • Drained diesel and refilled (had stabilizers, was old)
  • Drained and inspected the Filter Bowl for debris (perfectly clean)
  • Changed the Fuel Filter (just because)
  • Checked Fuel Pressure from Transfer Pump ( > 30psi while cranking)

  • Checked system grounds (seem ok)
  • Checked all fuses (none shot, fine)
  • Checked underhood power system relays (fine)
  • Checked GPR operation (works fine)
  • Checked ICP and IPR (wiring is fine)
  • Checked CPS harness (wiring is fine)

Oil System
  • Running Amsoil Synthetic (clean; changed just prior to sitting)
  • HPOP oil level checked (1/2 from top; consistently fine)
  • System Oil pressure pops up a few seconds into cranking (understand this is correct)
  • No high-pressure oil leaks.

I am making a few other assumptions here:
-The CPS is fine as I'm getting RPM readings both via OBD2 and through the Ford Idle Control Module.
-The injection system is getting solid pressure during cranking (see below) and the IPR duty cycle suggests it is functioning also.

I'm more than 150km from the nearest Ford Dealership so I am reluctant to get it towed, so I decided I should go ahead and get some further data - picked up an OBDLink and ScanXL with the Ford package. I am trying to borrow a NGS tool to do a buzz test, etc but haven't had any luck yet - might need to track down and bribe some techs!

I will post the graphed output from my OBD data collection in the next post, as I'm a (total!) forum nub, and can't put an image or link in my first post!

The one weird thing that springs out at me is the system voltage seem unusually low during cranking; both batteries have been load-tested, and charged, and usually while doing a series of crank tests, I have the shop charger in 300A starting mode on it.

Hoping someone can point me in the right direction here; I can provide more information and look forward to a different perspective on this!
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post #2 of 6 (permalink) Old 06-06-2010, 07:23 PM Thread Starter
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This is two cranking attempts:
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post #3 of 6 (permalink) Old 06-09-2010, 05:42 AM
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I'm still learning about HEUI so I'm posting to comment on a couple things and to subscribe. I did notice the big voltage drop while you were cranking and I have heard that the IDM cannot fire the injectors if the voltage drops too low. You might try a voltmeter directly at the batteries while cranking in case there is a voltage drop at the DLC causing a false readout.
I also am wondering if the IPR duty cycle and the ICP pressure should go that high at cranking? Maybe the IPR is clogged at the screen, and the PCM is trying to demand more pressure?

Hopefully a tech will post soon, meanwhile I wonder if you should try two different batteries and maybe service the IPR?

Also, have you tried starting it with the ICP sensor unplugged? Be careful the plastic top part of the ICP gets brittle when old, mine broke off and cost me $150.00.

What is the spec for fuel pressure on the 96? I know the 99-03 7.3 needs about 50psi. Did you check for a good flow of fuel, after sitting that long something could be clogged up.

2002 F 350 4x4 Crew

Last edited by bigb56; 06-09-2010 at 05:54 AM.
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post #4 of 6 (permalink) Old 06-11-2010, 02:20 PM
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Any progress?

2002 F 350 4x4 Crew
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post #5 of 6 (permalink) Old 06-16-2010, 11:55 PM Thread Starter
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There were a lot of great comments on various forums - here's a synopsis of what feedback I got from my OP:

- OMG it's always the CPS!1!

I was getting a rpm reading, but some people report failed CPS and still have reliable RPM (presumably via crank sensor).. a 30 dollar part that I should have a backup of in the van? I bought the updated International part and put it in.

- with GP on might give insufficient voltage for all the PCM/IDM to come online/sync

Went ahead and replaced the batteries - I was going to do that eventually as my old ones were on the way out.

Fuel Pressure is low:
- transfer pump could be bad
- could be a blockage from sediment, tank crap, or bits of o-rings

On a '96 ~30psi while cranking is acceptable (99-03 should be 50 psi cranking). I was still pretty concerned about the stale old fuel and since it clearly wasn't fuelling, I did a lot of poking around at the return lines, peering into crevasses in the fuel filter bowl, etc. I did actually find some black fibrous material in the screen leading to the pressure regulator, but not enough to be the sole cause of the fuelling issues. (I think it was a scrap of the (slightly ratty) hutch liner).

ICP looks too high:
- ICP sensor failure
- IPR stuck 'open'

I verified the correct function and output values of the ICP Sensor, although disconnecting it *completely failed to generate a code* (This is weird, and something I need to sort out). It also didn't change any of the system behaviour during cranking.

I was worried that the IPR was stuck but after checking some diagrams of the HPO IPR gate and layout, the 'off' (not energized) position of the IPR leaves the drain route open. From what I've read, with the IPR locked in the de-energized position, you would never see > 200psi HPO, which ruled out it being stuck. The duty cycle shown on the graphs falls right into line with the expected numbers - should come up to ~14~ KOEO, and come up to a 45% (max of 54%) on cranking prior to start.

Bad IDM:
- pulse width looked wrong to some folks, as 2-2.2 ms isn't much injector time
- it's clearly not actually fuelling, so if all above things considered fine, it must be the IDM with some weird error/hardware failure or wiring issue.

I ohm'd out the IDM wiring harness more than once; checked pins, traced stuff around and ended up fixing some abraded bits of harness (unrelated powertrain stuff). Doing a little reading on the startup Pulse Width I discovered the following: 0 ms means the PCM is in the no-sync state (between crank and cps) 0.42ms indicates PCM/IDM sync meaning the PCM waits on ICP to hit minimum cranking pressures (~700psi). At this point, the PW should change to 1-6ms depending on the fuel demand calculations.

It was pissing me off that *everything* looked like appropriate start conditions. I thought I'd like to see some of the result of the 2ms PW for myself, and hooked up a tiny 110V bulb to the B/C pins on the 3/7# connection (I think) and .. no flash, nothing I could see at least.. I then checked the "C" 110VDC pin on Injector harness connection (on the valve gasket) and .. KOEO gave me ~1.1 VDC. Yes, 1/10th of what I expected to see.

This morning I checked the Under Hood Fuse Box (for like, the 4th time) before pulling the IDM harness off again to see if it was getting appropriate voltage. I had previously bench tested the relays, and replaced the PCM relay as it seemed questionable, and this time I just replaced the IDM relay with a new one, and thought I'd give it another 'crank test'.

Bloody thing started; nearly caused my to fall out of the passenger door with my laptop in hand - had expected to log a bit more data of a no-start and instead it ran like a clock. Turned it off, reassembled the intake hoses etc, and cleared a path out of the shop. Started instantly, warmed it, and checked some roadworthiness stuff and half an hour later drove it for 20min or so to let the PCM get reacquainted with the engine.

Runs like a damned clock it does.

I guess I made a key mistake with my assumptions about DTC's and such - there are a multitude of OBD codes that indicate IDM problems and many kind of injector issues; I wasn't getting any, and to all appearances it was a subsystem functioning correctly.

Turns out the relay was partially functioning (ie: primary closes, second makes connection that fails under load). Looked fine to the DMM on the bench - Noting the full voltage/amps behaviour varies from DMM is another mistake I shouldn't have made with a power subsystem.

Ah well, live and learn!

Thanks to all the folks that posted feedback and other resources in this forum; I've learnt a ton about my van and wouldn't have even tried without the knowledge that other people on these forums can make it happen too!

Some offsite Links that were great: (I hope it's cool if I link em; didn't find this info in many other places)

Ford Diesel Power Forums - View Single Post - No Start 01 7.3
- great little rundown at DMM testing some 'obvious' stuff that your scantool might lie about

- 94 - 03 7.3L Diagnostics on PDF which has some insightful numbers

powerstroke pro
- More good voltage/resistance values and part numbers

Last edited by ambulant; 06-17-2010 at 12:10 AM. Reason: I spel gud
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post #6 of 6 (permalink) Old 06-17-2010, 02:33 AM
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Thanks for letting us know what it was, a lot of us follow these no start issues just so we will be better prepared when it happens to us.

So you just replaced the little ice cube relays for the PCM and IDM, right? Not the actual PCM and IDM units themselves?

2002 F 350 4x4 Crew
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