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Help! 7.3 No Start

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Old 09-16-2018, 01:02 PM
Nelson98
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Help! 7.3 No Start

Hey guys, I've got a early 99 7.3 with an edge evo tuner that I can monitor with. 2 days ago I had a crack no start but it was just a glow plug relay no big deal. Today I have a crank no start and I'm confused. My monitor reads I have 178ish rpm so I don't think it's my CPS, I unplugged my ICP still no start so I'm pretty sure that's good. I read 0 psi injection pressure though and that makes me think my IPR is bad but I'm not sure. Some possibly good info would be that my CPS, ICP, IPR, injector O rings, glow plugs, valve cover gaskets, fuel bowl heater, and fuel filter have all been replaced within the last 10,000 miles. I recently checked and filled my hpop with oil, and I gotta spare CPS and ICP in my glovebox I could throw at this thing before I have to go to the store. Thanks for looking!
 
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Old 09-18-2018, 07:25 AM
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Do you have fuel pressure?
 
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Old 09-18-2018, 08:19 AM
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I thought the motor had to hit 500 rpm before the injectors would fire?
 
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Old 09-18-2018, 08:47 AM
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No. ICP pressure has to hit 500 psi before it will fire the injectors.
 
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Old 09-18-2018, 09:42 AM
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Originally Posted by thomabb View Post
I thought the motor had to hit 500 rpm before the injectors would fire?
RPMs need to be at least 100 for the injectors to fire.
 
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Old 09-18-2018, 12:05 PM
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Update

I'm pretty sure i've got fuel pressure but I haven't put a gauge on it. I got the damn thing to start after cranking forever. Watched my icp value go up from 0 to 500 by tens, once it finally got there it fired and magically had oil pressure again. But it ran like dog ****, stutters, stumbles at 1800 rpm, I'm stumped.
 
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Old 09-18-2018, 12:34 PM
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If you're hearing your fuel pump run when you turn your key on then you're probably okay (it's on the inboard side of the frame rail under the driver's door).

What brand of sensors did you use? You can get lucky but for the most part our trucks like OEM. You can unplug the ICP sensor and see how it starts/idles. If that fixes the problem then it's that sensor. Also check the plug for oil. Yes, I know you replaced it 10K miles ago but I've seen stranger things happen. It's free so you've got nothing to lose.

Dumb question - have you checked your oil level? The 7.3L doesn't need to be topped off but when it starts to get low it will let you know.
 
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Old 09-18-2018, 05:09 PM
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Can you get us a couple of parameters from the edge to help you troubleshoot? Batt voltage, ICP(psi), IPR (%), RPM. Check the HPOP res level again
 

Last edited by j1586; 09-18-2018 at 05:13 PM. Reason: forgot info
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Old 09-21-2018, 05:54 PM
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I replaced most the sensors from napa and the ipr from oreilly's, I unplugged the icp and it still ran like ****. I even threw a known good one on and it didn't change anything. Some values I'm getting are about 180rpm cold, the ipr duty cycle goes up to about 94-98%, my icp slowly goes up pretty much by 10's 10,20,30,40 for like 15-20 seconds of cranking where it eventually reaches 500 and starts up. The idle is rough as hell and it's got no power, at about 1800rpm the thing almost sputters and pops. Thanks guys
 
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Old 09-21-2018, 05:57 PM
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Oh and batteries, cables, and alternator are new as of May, voltage is good at about 12 cranking and 14 running as it should, thing cranks hard and fast
 
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Old 09-21-2018, 07:34 PM
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Check the HPOP res level again, if it is not going down then the problem is in the High Pressure oil system. From experience I would start with the injector orings. If you have a scan tool (ford, AE) that does a power balance/cylinder contribution test it can help narrow it down. If not you can replace all of them with the engine still in the truck. If one has failed I would recommend doing other of them.
 
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Old 09-21-2018, 07:36 PM
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Attached is a data log collected by my edge tuner of a short run around the block I did after I finally got it to fire. I honestly think the values are fine but the thing runs awful and knocked a few times. Oh and yes I did check the oil level, it is right where it should be.
 
Attached Files
File Type: csv
data_logging_run_5.csv (1.63 MB, 1 views)
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Old 09-21-2018, 07:52 PM
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HPOP level is about a half inch from the top, injector o rings were done 10,000 miles ago. I think I'm gonna need to find someone with AE
 
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Old 09-22-2018, 09:53 AM
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Where are you at? I had this same problem. I could only start/ run the truck in a high rpm setting on the tuner. When I pulled the injectors 4 were leaking by and 2 others were almost completely blown out. Are you getting any black smoke? If that is the problem the truck will get harder and harder to start. It will not start when hot and eventually not start at all.
 
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Old 09-22-2018, 11:23 AM
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Originally Posted by Nelson98 View Post
I replaced most the sensors from napa and the ipr from oreilly's,

I unplugged the icp and it still ran like ****. I even threw a known good one on and it didn't change anything. Some values I'm getting are about 180rpm cold, the ipr duty cycle goes up to about 94-98%, my icp slowly goes up pretty much by 10's 10,20,30,40 for like 15-20 seconds of cranking where it eventually reaches 500 and starts up. The idle is rough as hell and it's got no power, at about 1800rpm the thing almost sputters and pops. Thanks guys
This is most likely your problem. Our 7.3L do NOT like aftermarket sensors period. Motorcraft OEM ONLY! I bought a NAPA ICP when I bought my truck it lasted about 1 hour! Unless it’s a Motorcraft it’s not a known good one. I would start over with OEM sensors.
‘Buy your sensors from Ford or Clay at RiffRaff Diesel and you’ll get quality sensors you KNOW are OEM.
 

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