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99 & up 7.3L Power Stroke Engine and Drivetrain Discussion of the 99 & up 7.3L Power Stroke diesel engine and drivetrain in the 1999-Up Super Duty trucks and Excursions. No gas engine discussion allowed except on transmissions and drivetrain that pertain to all models. Please confine discussion of topics in this forum to those items that are specific to the 7.3L Power Stroke engine.

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Old 06-11-2011, 10:47 PM   #1 (permalink)
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HELP!!7.3 WON'T START

I have a 2002 f350 that I am chasing a problem. new icp, new ipr, new HPOP,New fuel pump with prefilter, fresh batts and fuel in the bowl and no start.

ran AE scan tool before HPOP replaced.
1. Injector buzz test passed with no problems.
2. When we tried to run the cylinder contribution test, the engine died as soon as the first injector was dropped out by the test - I don't think it related to that injector.the RPM dropped too much. We repeated the test and the same thing happened again.
3. I have a DP tuner, and the engine would only stay running if the tuner was on the high idle program. If you took it back to stock, the engine died immediately.

The IPR Duty Cycle is at about 14% with the engine off, jumps up to about 65% while cranking, and then came back down to about 14% once the engine is running. ICP was around 650-700 psig.

I have replaced the fuel filter, injector cups & o-rings.

Before hpop replacement it would start with small amount of starting fluid but will not stay running at low speed/idle. after the replacement i finally got it started and it even would idle down. it died while idling and hasn't started since.

I am in Ct and have to be in TX in 2 weeks! any help would be appreciated.
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Old 06-11-2011, 11:10 PM   #2 (permalink)
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Been having same issues, so I definitely know what you are going thru.
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Old 06-12-2011, 07:53 AM   #3 (permalink)
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IPR maxing out while cranking to start means you're having trouble building oil pressure. How long has it been since you replaced the HPOP and injectors? You've got to get the air out of the rails for it to start quicker.

What is the IRP % when the truck does start up? ICP and IPR will stay higher for a little bit while the engine warms up, then when ICP drops to around 500 psi at idle, what does the IPR % look like? Any sign of oil in the bottom of your fuel filter bowl?
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Old 06-12-2011, 08:17 AM   #4 (permalink)
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HPOP replaced on monday. truck has been cycled 20-30 times since. even ran for a 2-3 min period before dying.

no oil in fuel bowl

I don't have a scanner here. Greg in Ledyard hooked it up when my truck was running poorly but still runnning.

truck will not start at this point even on ether
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Old 06-12-2011, 04:57 PM   #5 (permalink)
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A couple of things come to mind.

You're most likely not building HP oil pressure, although it should kick over on ether (but that's not a recommended practice with a glow plug equipped engine - may break something when the ether fires prematurely).

Monitoring ICP and IPR duty cycle would tell the tale.

You said you'd replace injector cups and o-rings. Any possibility that one or more injectors bolts were not tightened properly? That may cause the top oil o-rings to blow out, and if that happens, you won't get any HP oil pressure.

You're going to have to go back to basics, as well as checking over the work you've done.

Check all the wiring connectors that you had apart.

Check cranking voltage. If it's low, you may not be getting adequate cranking speed (100 rpm min). Your batteries may be low from the starting attempts.

Check all your fuses with a multimeter or fuse tester. Maybe your're not getting power in the places needed to start.

Check the tin nut on the back of the IPR. If the coil has fallen off, you won't get it to start.

Check that the PCM is putting out the 5V Vref signal. It should show up on one of the 3 wires on the ICP connector.

Try replacing the CPS. If it's bad, you won't get it started.

Good luck.
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Old 06-12-2011, 05:18 PM   #6 (permalink)
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If you need the use of AE again, let me know. I'm available late Monday evening, Tuesday-Thursday after about 5 p.m., Friday late evening, and anytime next weekend. I can come to you since it sounds like your truck isn't running now. I'll bring it to work with me if you want me to stop by day after work.

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Old 06-12-2011, 08:02 PM   #7 (permalink)
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Cups were replaced over a year ago due to fuel in radiator

batteries have lived on the charger since monday(2amp rate/6 during start attempts)cranking voltage is 11.5v

all started as truck would not start without ether (changed cps)

then it would not run at low rpms.(changed icp and ip.r loctite on ipr nut)

truck still would not start on its own

hpop reservoir would drain down(replaced hpop) reservoir stayed full and truck would idle down but died after 3 min and has not started since.

icp replaced due to oil in connector


ipr replaced due to bad impeadance

fuel pump was original an slow to fill fuel bowl

what fuses specifically am i looking for and at what times? (key on, cranking.....)

when is the 5v icp voltage valid? I unplugged it in hopes it would default value but truck still would not start.
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Old 06-12-2011, 08:44 PM   #8 (permalink)
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Greg,
I will definately take you up on that offer. call me tomorrow when you get off.
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Old 06-12-2011, 09:29 PM   #9 (permalink)
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Are you sure you have fuel pressure?
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Old 06-12-2011, 09:31 PM   #10 (permalink)
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new fuel pump.good pressure.
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Old 06-13-2011, 02:26 AM   #11 (permalink)
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Quote:
Originally Posted by j1586 View Post
hpop reservoir would drain down(replaced hpop) reservoir stayed full and truck would idle down but died after 3 min and has not started since.
Have you checked the reservoir lately? The quick fill check valve under the plug in the valley directly underneath the fuel return connection could be the issue, possibly not the HPOP.

Quote:
Originally Posted by j1586 View Post
what fuses specifically am i looking for and at what times? (key on, cranking.....)
I'd probably just check them all, with key on. Just run thru the fuse boxes with a multimeter, hitting both sides of all the fuses.

Quote:
Originally Posted by j1586 View Post
when is the 5v icp voltage valid? I unplugged it in hopes it would default value but truck still would not start.
You should have 5V on the Vref circuit when the key is on. It feeds all the 3-wire sensors, and if it's getting drug down below 5V by a short or bad sensor, it could affect what the sensors report back to the PCM on the signal wire. You might try unplugging the other 3-wire sensors and see what happens. EBP sensor has caused problems for some. MAP sensor and CPS are the other 3-wire devices, but of course you can't unplug the CPS and expect it to start. The brown/white wire is Vref. You can monitor Vref with AE.

Hope that helps you track it down.
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99.5 F250 PSD Supercab LB 4x4, ZF-6 w/SB Con OFE, 3.73LS, Boost & pyro gauges, Swamps S175/146 injectors, DP 80 HP Econo PCM (classic version), AIS, coolant filter w/"hokum" bracket, regulated return, heated mirror mod, lighted cupholder, Marinco heater plug-in.

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Old 06-13-2011, 05:37 AM   #12 (permalink)
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reservoir is still full. how do you check the check valve and or correct the issue?
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Old 06-13-2011, 07:16 AM   #13 (permalink)
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If the hpop isn't bleeding down, the checkvalve is working.

I think I would pull both valve covers and then re-connect the harness. Cranking the engine over should produce oil from each injector spout if they are firing. Watching the base of the injectors for oil will show a bad o-ring. If you can get AE hooked up on it, it could be helpful in diagnosis.
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Old 06-14-2011, 09:29 PM   #14 (permalink)
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We hooked up my AE to it this evening & found the following:

-The engine never started, but cranked fine. It did not ever try to fire.

-Vref (as monitored by AE) was 5.02 volts - we didn't actually measure at a connector

-Engine RPM (as monitored by AE) while cranking was about 130 rpm, so I believe the CPS is fine

-I almost missed the fuel injector pulse width, but I saw .6 msec when we were cranking

-IPR duty cycle was about 14% when not cranking, and quickly went up to almost 70% while cranking, and then back down to 14% when cranking stopped. ICP read 0 psig (don't know why, but we know this is a problem). When we tried it over a month ago, we were getting around 600 psig.

-We unplugged the ICP and tried cranking again. IPR duty cycle was about 14 % when not cranking, and went to about 35% while cranking, and then back down to 14% when cranking stopped. ICP was about 2300 psig.

-Engine RPM was about 130 rpm while cranking. There was a multimeter connected to the batteries and voltage never went below 11 vdc while cranking.

-Several weeks ago, the engine would stay running only when given a shot of starting fluid and running the high idle tune on a DP Tuner. The engine would die as soon as a tune with a lower idle speed was selected. I don't know the exact workings of the HPOP, but my guess is that the higher engine RPM allowed the HPOP to overcome the pressure loss from a leak somewhere.

-For reference, I monitored ICP and IPR duty cycle on my truck while starting (it runs fine with no problems) and saw no higher than 35% IPR duty cycle while cranking (about 14% once running) and ICP was around 500-600 psig while cranking.

I think I'm seeing 2 issues here:
1) ICP definitely has something wrong - either bad sensor or bad communication to PCM.
2) IPR duty cycle seems too high - my guess is a leak in the high pressure oil system somewhere. Since there are no external oil leaks, my guess is an injector o-ring.

Any other thoughts on this?

Thanks,

Greg




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Old 06-14-2011, 11:15 PM   #15 (permalink)
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I would pull the IPR and inspect it and ensure the o-rings are good. The IPR duty% is only a command by the PCM, and effects are monitored by the ICP. The PCM has no means of ensuring the IPR is actually doing what is commanded other than the ICP reading. If you unplugged the ICP, you eliminated potential biasing from the sensor. That didn't have an effect though. I'd ensure both o-rings on the IPR are good (I know it's new, but still), and if that checks out I'd pop the valve covers and reconnect the harness and crank it over, looking for oil coming from the base of the injector.

When you had AE hooked up, did you perform a KOEO and buzz test? Not that the injectors solenoids are preventing hp oil, but always a good idea to perform when troubleshooting.

I might be all wet on this one since I've never pulled the HPOP, but how is it driven? Any way the drive could get damaged?
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Triple Pillar Gauges; Fuel pres, Pyro, Boost
AE, Alldatadiy, and half a clue
- AKA "The Big White Truck"
______________________________________________
The first part to be thrown at these trucks should be a PSD compatible scanner

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