96 F-350 with powerstroke won't start

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09-11-2013, 01:44 AM

DougH000

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96 F-350 with powerstroke won't start

Got off at midnight, and my truck won't start. Since this isn't the first time it won't start, I knew where to look for the same symptoms.

Good batteries (and VPWR)
RPM is about 150
IPRDC goes quickly to 54%
ICP camps out around 200 psi
Fuel is full in the fuel bowl
HPOP is full

No codes

WTS light comes on normally

Buzz test is good

I followed someone's suggestion and disconnected the ICP to see if it would start...no it doesn't. But when I did this, IPRDC was only 35.

I checked all fuses (including the #22), and they are all good.

It's dark out, so I can't be 100% positive, but no smoke out of the tailpipe.

From prior experience, the truck will start in an hour or two, but this is getting frustrating. I would take it to a mechanic to find the problem, but it only does this every 4-10 days.

CPS is new
Injector orings is new
ICP is new
Fresh oil in engine and HPOP.
EBP sensor is new and the tube is cleaned out

Where do I go from here?

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09-11-2013, 04:59 AM

tshrager

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This should get you started. I'm headed to work.

https://docs.google.com/file/d/0Byb4.../preview?pli=1

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09-11-2013, 05:52 AM

DIYMechanic

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The PCM has to see at least 500 PSI of High Pressure Oil at the ICP in order for it to fire the injectors. If you're only seeing 200 PSI and it is happening at 54% IPR Duty Cycle, that is where you need to start. Check the IPR itself and make sure that the tin nut on the solenoid hasn't fallen off and let the solenoid get loose on the shaft of the IPR. If that is truly the correct ICP pressure, that is why the truck won't start. You just need to figure out why you're not getting a good ICP pressure (or reading).

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09-11-2013, 08:06 AM

DougH000

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I realize that, yet I'm at a loss. The tin nut is tight. There are no visual leaks. And this problem has been there before, and when you check an hour later the truck starts and runs like nothing was every wrong. 4+ days later, it repeats itself. I ended up getting towed home, and as of 4 this morning it still won't start. Is there a good way to test the IPR? I replaced it just under 3 years ago.

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09-11-2013, 08:32 AM

madpogue

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RPM seems slow (should be 200-300, right?). If you're sure your batteries are strong, and the connections are good, I'd say the starter is tired. Might explain the slow crank plus the low injection pressure.

Is it a 5-speed, and is it in a place where you could pull/push start it with another truck?

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09-11-2013, 08:33 AM

DIYMechanic

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Here is what I have for testing the ICP and IPR:

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ontGrowAutofit/> <w:SplitPgBreakAndParaMark/> <w:EnableOpenTypeKerning/> <w

ontFlipMirrorIndents/> <w:OverrideTableStyleHps/> </w:Compatibility> <m:mathPr> <m:mathFont m:val="Cambria Math"/> <m:brkBin m:val="before"/> <m:brkBinSub m:val="--"/> <m:smallFrac m:val="off"/> <m:dispDef/> <m:lMargin m:val="0"/> <m:rMargin m:val="0"/> <m:defJc m:val="centerGroup"/> <m:wrapIndent m:val="1440"/> <m:intLim m:val="subSup"/> <m:naryLim m:val="undOvr"/> </m:mathPr></w:WordDocument> </xml><![endif]--> ICP:
500 PSI ICP pressure needed to fire injectors. Unplugging the ICP will cause the PCM to default to around 750 PSI on the IPR.

Holding the ICP connector looking into it with the latch on top, the left pin is Vref, center is ICP signal, and right is Signal return. The corresponding wire colors should be brown/white, dark blue/light green, and grey/red.

At key on, you should get a .25v to .4v signal. Operational range for the sensor is .65v to 3.25v. Some approximate pressures compared to voltage signal would be:
500psi = about .85-.87v
1000psi = about 1.4v
1800psi = about 2.3v
2400psi = about 3v
3000psi = about 3.8v

IPR Troubleshooting:

IPR connector unplugged - Key Off

Red wire > 1000 ohms - use battery negative for meter ground
Yellow wire > 1000 ohms - use battery negative for meter ground

IPR connector unplugged - Key ON

Red wire Battery (12 volts) - use battery negative for meter ground
Yellow wire 0 - .25 volts - use battery negative for meter ground

IPR connector plugged in - Key OFF

(Measuring across Red - Yellow wires) 5-20 ohms

Hopefully that helps. And yeah, I would make sure you're cranking fast enough to start the truck too. Check the voltage at the battery while you're cranking as well and make sure you're still above 10.5 volts.<!--[if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority

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09-11-2013, 09:24 AM

DougH000

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madpogue- the truck has always cranked around those RPMs. Just to make sure on the battery issue though, when the tow truck dropped my truck at the house, putting the batteries on a charger was the first thing I did before going to bed, just because I knew I would be cranking some more. I was able to get it started...kinda.... this morning. And after dying about 20 times, I was able to get the truck into the driveway so I can work on it there. No, the truck is an automatic.

DIYMechanic- Thanks for the test chart. It'll help when I take a whack at it tonight.

tshrager- thanks for the flowchart

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96 F-350 with powerstroke won't start

96 F-350 with powerstroke won't start

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