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Discussion Starter · #1 ·
Hey all I'm a new member to this group and already love it and read threads everyday, but now its my turn to look for help. My truck has been sitting for a little over a year because I was too lazy to tear into it. I pulled the valve covers off and had a loose uvch, I fixed the issue, put the truck back together and charged the batteries for a little over a day each. My dad started the truck after charging the batteries and said it ran better than it ever had. He let it run for about 15 minutes and shut it off. I came the next day and "started" it and it ran like crap. It was shaking, and knocking and it shut itself off after a minute of running. My BIL hooked up his scanner and it had a P1670 code but that was all the scanner said. What are the chances that new batteries is all the truck calls for? I hate to throw a bunch of money at it without knowing what the truck needs. Any help is greatly appreciated
 

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Hey all I'm a new member to this group and already love it and read threads everyday, but now its my turn to look for help. My truck has been sitting for a little over a year because I was too lazy to tear into it. I pulled the valve covers off and had a loose uvch, I fixed the issue, put the truck back together and charged the batteries for a little over a day each. My dad started the truck after charging the batteries and said it ran better than it ever had. He let it run for about 15 minutes and shut it off. I came the next day and "started" it and it ran like crap. It was shaking, and knocking and it shut itself off after a minute of running. My BIL hooked up his scanner and it had a P1670 code but that was all the scanner said. What are the chances that new batteries is all the truck calls for? I hate to throw a bunch of money at it without knowing what the truck needs. Any help is greatly appreciated
I wouldn't go buying new battery's that's not really gonna effect a rough idle. The IDM might be the problem.
 

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Did you put in some fresh fuel and a new fuel filter? Drain the fuel bowl? At this point I would get a fuel pressure gauge, after sitting for a year you could have some fuel delivery issues. Knocking often points to a fuel issue on a diesel.
 
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Discussion Starter · #4 ·
I'm just having a hard time wrapping my head around how it started up and ran perfect right after the job was done, but the very next day it ran horribly. Could there be an issue with air somewhere in the system? I plan on getting 10 gallons of fuel and dumping in the tank along with some additive. The gauge reads right around a quarter tank but I know that when it gets around that amout the gauge isn't the most trustworthy.
 

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Star,

Welcome to PSN! What kind of scanner does your BIL have? It must be higher end if it read the codes of the the truck. If it is available for your use you should run a buzz test. As for the shaking... I inclined to think you may still have some problems on the electrical side.. something I have posted on many threads:
"I would recommend that you first invest in FORScan (forscan.org) and a suitable adapter. I have an OBDLink EX usb adapter (should you wish to use a computer to collect data), or take a look at either a BAFX or OBDLink unit. Both BAFX/OBDLink have a bluetooth/Wifi units (there are a few folks around here that recommend them) that will would work with a smart phone (Run of the mill box store scanners and even a great number of the higher end scanners can't touch these trucks as Ford used the "heavy duty diesel" protocol for communication). Once you are setup I would capture data.. At minimum I would save RPM (really this is CPS), ICP, IPR, MAP, EOT and IVS (at least I think that is the PID for the go petal). FORScan will allow you to save the data as a .csv file which you can import into excel. The information you get from the truck will help identify what your problem really is without just "throwing parts" at the truck."
I would run a buzz test on the injectors to see what you can hear. You want to know if they are all firing and if they all sound the same.

Another possibility is that you are getting air into the fuel system. A quarter tank is about where the fuel pickup assembly is uncovered. If there are any bad seals in the pickup, the engine will pull air into the fuel line. Add fuel and see if the rough running goes away.

Cj
 

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If your tank has never been removed and parts changed the pickup foot has likely disintegrated and fell off by now, happens to all of them. Once that's gone you will start sucking air and running out of fuel at around 1/4 tank. Suggest you Google the "Hutch Mod", it fixes all the tank and pickup issues that are common on our trucks.
 

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Discussion Starter · #7 ·
He did a buzz test and I could hear all injectors buzz and they all sounded identical. Is forscan any good on android? I don't have a good laptop that wouldn't give me a hard time. I'd like to have some kind of easy scanner for reading codes and checking info on the truck. Is there any benefit to use forscan over torquepro or car gauge pro? I'd like to have something useful but also user friendly as I'm not super inclined with the computer aspect of vehicles
 

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Okay so the buzz test was successful... I'd fill the tank up full and then check and fill if need the fuel filter bowl before starting the truck again. As for FORScan - lots of guys here on PSN use it with android with good results. I use it on a laptop myself. FORScan was specifically designed for Ford's and Mazda vehicles where Torquepro is more generic (at least from what I have noticed). I use FORScan with my truck and OBDWiz (comes with the OBDLink adaptors) for other brands of vehicles. I didn't find FORScan too hard to setup. Getting the right PIDs took some experimenting (some of them have more than one option).
 

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Discussion Starter · #9 ·
Okay so the buzz test was successful... I'd fill the tank up full and then check and fill if need the fuel filter bowl before starting the truck again. As for FORScan - lots of guys here on PSN use it with android with good results. I use it on a laptop myself. FORScan was specifically designed for Ford's and Mazda vehicles where Torquepro is more generic (at least from what I have noticed). I use FORScan with my truck and OBDWiz (comes with the OBDLink adaptors) for other brands of vehicles. I didn't find FORScan too hard to setup. Getting the right PIDs took some experimenting (some of them have more than one option).
Oh yeah that's the part I forgot to mention. There is fuel in the fuel bowl. Wouldn't that mean that the truck should at least start and run on the fuel in the bowl? Or does that not necessarily hold true? I'll definitely put at least 10 gallons in the tank. I'm just so confused as to where to start. I watched a DieselTech Ron video about checking the fuel pressure and running a hose from a fuel jug into the pump to see if the problem was in the tank. I might have to give that test a shot. I'm just stumped as to where to look. The scanner gave us a P1670 code (electrical code) and he said the icp pressure was around 2200psi but I'm pretty new to diesel repairs so all of that kinda goes over my head but I thought 2200psi sounded kinda high. (Which the pinned no start thread linked that high of a pressure to an electrical fault as well) which is why I was curious that the fairly old batteries may have been causing some issue, since it started perfectly fine after they were charged...unless the pickup in the tank sucked up some dirt or whatever.
 

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These trucks use the HEUI system to inject fuel. HEUI - Hydraulic Electric Unit Injector. The ICP pressure will range from 600 psi (idle) up to 3000 PSI (at full bore). 2200 at starting is not out of the ordinary. Good place to read up on the 7.3 - https://deadheaddiesel.com/7-3-powerstroke-specs/ . Good breakdown of the HUEI system: HEUI - How High-Pressure Oil Injection Systems Work
You have an advantage over my 97 in that you have an electric fuel pump that lifts fuel to the fuel bowl. This pump kicks on to pressurize before you start the truck so you should be able to able to see bubbles without starting the truck. As for the code... You could still have an electrical problem in the wiring harness. It might be worth looking at the UVCHs again to double check the connections.

Cj
 

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Discussion Starter · #11 ·
These trucks use the HEUI system to inject fuel. HEUI - Hydraulic Electric Unit Injector. The ICP pressure will range from 600 psi (idle) up to 3000 PSI (at full bore). 2200 at starting is not out of the ordinary. Good place to read up on the 7.3 - https://deadheaddiesel.com/7-3-powerstroke-specs/ . Good breakdown of the HUEI system: HEUI - How High-Pressure Oil Injection Systems Work
You have an advantage over my 97 in that you have an electric fuel pump that lifts fuel to the fuel bowl. This pump kicks on to pressurize before you start the truck so you should be able to able to see bubbles without starting the truck. As for the code... You could still have an electrical problem in the wiring harness. It might be worth looking at the UVCHs again to double check the connections.

Cj
Finally got my scanner and hooked it up to my phone to check the icp and ipr while I cranked. The icp was saying around 2200 psi again with no start but when I checked the codes for the truck to see what the computer had to say, I only saw a code for the batteries. Gonna get 2 new batteries and try to start it again. Hopefully all will go well. I appreciate your help. I've been looking forward to the obd2 scanner. Never thought they'd be worth it but I'm starting to wish I woulda gotten one years ago
 

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If new batteries gets the truck running again I would suggest having the alternator tested to make sure it is healthy.
 

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Discussion Starter · #13 · (Edited)
I replaced the batteries and that cleared the P1670 code, I also changed the oil. I can get the truck to start now and it still idles somewhat rough. After a while of idling it will die altogether. When I rev and hold the idle at 2k it'll be super smooth but once I let off it goes back to the rough idle. I forgot to unplug the icp while it was running to see if the idle cleared up. What would you suggest I check? I saw where I can unplug the icp and the ipr while idling to see if anything changes. The icp was around 470 psi at idle, I forgot to check the ipr% though. Guess I'll drop the tank if nothing else changes. Does it sound like a good place to start?
 

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If you unplug the IPR the engine will die out right. Looking at logged data... my 97 idles at 580 psi on the high pressure oil which is around 11% on the IPR. What are your ICP and IPR values while at idle?

Cj
 

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Discussion Starter · #15 · (Edited)
I turned my truck on and let it idle, it was still idling kinda rough but my ipr was 23% and my icp was hovering right around 1000 psi (last evening it was pretty constant at idle at right around 470). With the koeo the ipr was reading 14.84%
 

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The 14.84% reading is the default IPR setting in the PCM before starting. Those are odd values for idling. Looking at my data at 1000 psi my IPR was around 16%. Could be that you have some air in the high pressure oil rail. Have you driven the truck around much?

Cj
 

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Discussion Starter · #17 ·
No I just recently got the uvch taken care of and have a dead inspection. Trying to get it back up and running to get it inspected. If I rev and hold at 2k it is really smooth. But once I let off it idles pretty low and rough with some knocking until it eventually dies. Kinda what was leading me towards looking into the fuel tank. To my knowledge the tank has never been dropped and I have 250k miles
 

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How full is your tank? I'm just about to roll over 254k on my truck and haven't had any problems. The fuel pickup foot in my rear tank is falling apart so I can only get to about half the fuel load. I wonder if you have some water in the fuel.
 

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Discussion Starter · #19 ·
The gauge (if correct) is reading right around a quarter of a tank. It shows just a hair more than a quarter but I'm not 100% sure if that can be trusted. I saw a diesel tech Ron video about unhooking the hose going from the tank to the fuel pump and running a hose from a fuel jug into the fuel pump and starting the truck to see what happens to know whether or not the fuel screens are clogged or not. I also read something from RiffRaff about the icp and ipr readings and they made it sound like the icp and ipr numbers start to drop when the truck starts to warm up. When I started it and let it idle today I didn't let it run long enough to get warmed up. Seems like after a little while of idling it'll start to die off on its own until it eventually cuts off. I thought about putting in a few gallons of fuel but hate to just in case the tank needs to be dropped
 

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Quarter tank is where my coworker's 00 truck would start sucking air. The pick up foot was fine, but the where the draw tube (that leads out of the tank) hooks up to the plastic assembly there was a broken piece of plastic that allowed air to seep in around an o-ring. Hooking the truck up to a gas can sounds like a reasonable test. If you do have to go after the tank... Take the bed off. Much easier to access the tank that way. Be prepared to grind the bed bolts out though... As for the IPR and ICP. Cold, the IPR should be lower to maintain the correct pressure, while warm the IPR will need to increase to counter act the "runnier" oil.
 
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